Aims. We compared the clinical and radiological outcomes of using a polyetheretherketone cage with (TiPEEK) and without a titanium coating (PEEK) for instrumented transforaminal lumbar interbody fusion (TLIF). Materials and Methods. We conducted a randomised clinical pilot trial of 40 patients who were scheduled to undergo a TLIF procedure at one or two levels between L2 and L5. The Oswestry disability index (ODI), EuroQoL-5D, and back and leg pain were determined pre-operatively, and at three, six, and 12 months post-operatively. Fusion rates were assessed by thin slice CT at three months and by functional radiography at 12 months. Results. At final follow-up, one patient in each group had been lost to follow-up. Two patients in each of the PEEK and TiPEEK groups were revised for pseudarthrosis (p = 1.00). The rate of complete or partial fusion at three months was 91.7% in both groups. Overall, there were no significant differences in ODI or in radiological outcomes between the groups. Conclusion. Favourable results with identical clinical outcomes and a high rate of fusion was seen in both groups. The titanium coating appears to have no negative effects on outcome or safety in the short term. A future study to determine the effect of titanium coating is warranted. Cite this article: Bone Joint J 2017;99-B:1366–72

Periprosthetic joint infection (PJI) is one of the most dreaded complications after arthroplasty surgery; thus numerous approaches have been undertaken to equip metal surfaces with antibacterial properties. Due to its antimicrobial effects, silver is a promising coating for metallic surfaces, and several types of silver-coated arthroplasty implants are in clinical use today. However, silver can also exert toxic effects on eukaryotic cells both in the immediate vicinity of the coated implants and systemically. In most clinically-used implants, silver coatings are applied on bulk components that are not in direct contact with bone, such as in partial or total long bone arthroplasties used in tumour or complex revision surgery. These implants differ considerably in the coating method, total silver content, and silver release rates. Safety issues, such as the occurrence of argyria, have been a cause for concern, and the efficacy of silver coatings in terms of preventing PJI is also controversial. The application of silver coatings is uncommon on parts of implants intended for cementless fixation in host bone, but this option might be highly desirable since the modification of implant surfaces in order to improve osteoconductivity can also increase bacterial adhesion. Therefore, an optimal silver content that inhibits bacterial colonization while maintaining osteoconductivity is crucial if silver were to be applied as a coating on parts intended for bone contact. This review summarizes the different methods used to apply silver coatings to arthroplasty components, with a focus on the amount and duration of silver release from the different coatings; the available experience with silver-coated implants that are in clinical use today; and future strategies to balance the effects of silver on bacteria and eukaryotic cells, and to develop silver-coated titanium components suitable for bone ingrowth. Cite this article: Bone Joint J 2021;103-B(3):423–429

Bacterial infection related to orthopaedic implants is a significant complication today. One of the ways to reduce the incidence of implant-associated infections is assumed to give antibacterial activity to surface of implant itself. We focused attention on Ag, because it has a broad antibacterial spectrum, strong antimicrobial activity and low toxicity. In the previous works, sputtering, electrochemically deposition and sol-gel coating of Ag-containing hydroxyapatite (HA) have been reported. However, since practical technique of HA coating widely used for medical and dental implants has been the “thermal spraying” technique over the last two decades, we aimed at developing the novel thermal spraying technology for Ag-HA coating with antibacterial activity. In this study, physical and chemical properties, in vitro antibacterial activity, inhibition activity of bacterial attachment, HA-forming ability, cytotoxicity and release of Ag ions of the thermal-sprayed Ag-HA coating were evaluated. HA powder containing 3wt % of silver oxide (Ag2O) was sprayed on surface of titanium disks by the thermal spraying method using acetylene torch. SEM images showed a typical structure of the thermal-sprayed coating and the X-ray diffraction (XRD) pattern of the coating showed an amorphous structure. Ag residue in the coating was determined by the elementary analysis. The coating showed strong antibacterial activity and inhabitation activity of bacterial attachment to the methicillin-resistant Staphylococcus aureus (MRSA) in fetal bovine serum (FBS). On the other hand, the coating showed fast HA-forming ability in simulated body fluid (SBF) and no cytotoxicity related to Ag contained in the coating. Therefore, it is expected that the thermal-sprayed Ag-HA coating provides antibacterial and bone-bonding ability on the surface of the implant itself. In addition, though the HA coating is generally liable to adhere bacteria, the thermal-sprayed Ag-HA coating overcomes this problem. Pre-evaluation of release of Ag ions from the Ag-containing ceramic powders indicated that the releasing behavior of Ag ions in SBFs is dependent on the existing form of Ag in the Ag-containing material. It is assumed that most of Ag components in the Ag-HA coating are not retained as metallic Ag but as Ag2O in the amorphous layer. Time-course release tests of Ag ions from the coating in FBS showed a large release rate of Ag ions until 24 h after the immersion. It is expected that the Ag-HA coating could show strong antibacterial activity at the early post-operative stage. In the repeated release testing, the amount of released Ag ions was about 6500 ppb for the first release test, after which it gradually decreased. However, a significant release amount of Ag ions was observed even after the sixth repeat test. Therefore, it was assumed that the thermal-sprayed Ag-HA coating has a slow-release property of Ag ions in FBS

Total knee arthroplasty is one of the most common surgeries. About 92% of all implanted knee endorposthesis in 2020 were manufactured from uncoated CoCrMo articulating on ultra-high-molecular-weight polyethylene. All articluations generate wear particles and subsequent emission of metal ions due to the mechanical loading. These wear particles cause diverse negative reactions in the surrounding tissues and can lead to implant loosening. Coating technologies might offer the possibility to reduce this wear. Therefore, we investigated the applicability of tetrahedral amorphous carbon (ta-C) coating on CoCrMo alloy. Polished specimens made of CoCrMo wrought alloy according to ISO 5832-12 were coated with ta-C coatings with different layer structure using pulsed laser deposition (PLD). This process allows the deposition of ta-C coatings with low internal stress using an additional relaxation laser. Surface quality and mechanical properties of the coating were characterised using optical surface measurements (NanoFocus μsurf expert, NanoFocus AG) and a nanoindentation tester NHT. 3. (Anton Paar GmbH). Scratch tests were performed on Micro Scratch Tester MST. 3. (Anton Paar TriTec SA) to define the coating adhesion. Pin-on-plate tribological tests, with a polyethylene ball sliding on the ta-C-coated plate under a defined load according to ISO 14243-1 were performed using a linear tribometer (Anton Paar GmbH) to evaluate the tribological and wear properties. The ta-C coatings showed a mean roughness Ra of 5-20 nm and a hardness up to 60 GPa (n=3). The adhesion of the ta-C coatings (n=3) was comparable to the commercial coatings like TiN and TiNbN. The pin-on-plate tests showed an improvement of tribological properties in comparison with the polished uncoated CoCrMo specimens (n=3). The ta-C coatings applied by DLP technology show increased hardness compared to the base material and sufficient adhesion. Further research will be needed to investigate the optimal coating strategy for implant coating

Aim. A novel anti-infective biopolymer implant coating was developed to prevent bacterial biofilm formation and allow on-demand burst release of anti-infective silver (Ag) into the surrounding of the implant at any time after surgery via focused high-energy extracorporeal shock waves (fhESW). Method. A semi-crystalline Poly-L-lactic acid (PLLA) was loaded with homogeneously dissolved silver (Ag) applied onto Ti6Al4V discs. A fibroblast WST-1 assay was performed to ensure adequate biocompatibility of the Ag concentration at 6%. The prevention of early biofilm formation was investigated in a biofilm model with Staphylococcus epidermidis RP62A after incubation for 24 hours via quantitative bacteriology. In addition, the effect of released Ag after fhESW (Storz DUOLITH SD1: 4000 impulses, 1,24 mJ/mm. 2. , 3Hz, 162J) was assessed via optical density of bacterial cultures (Escherichia coli TG1, Staphylococcus epidermidis RP62A, Staphylococcus aureus 6850) and compared to an established electroplated silver coating. The amount of released Ag after the application of different intensities of fhESW was measured and compared to a control group without fhESW via graphite furnace atomic absorption spectrometry (GF-AAS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results. The coating with 6% Ag reduced Staphylococcus epidermidis biofilm formation by 99.7% (mean±SD: 2.1×10^5 ± 3,9×10^5 CFU/µL) compared to uncoated controls (6.8×10^7 ± 4.9×10^7 CFU/µL); (p=0.0001). After applying fhESW the commercially available electroplated silver coating did not prevent the growth of all tested bacterial strains. Bacterial growth is delayed with 4% Ag and completely inhibited with 6% Ag in the novel coating, except for a small increase of S. aureus after 17 hours. SEM and EDS confirmed a local disruption of the coating after fhESW. Conclusions. This novel anti-infective implant coating has the potential to prevent bacterial biofilm formation. The on-demand burst release of silver via fhESW could be an adjunctive in the treatment of implant related infection and is of particular interest in the concept of single stage revision surgery

Implant-related infection is one of the leading reasons for failure in orthopaedics and trauma, and results in high social and economic costs. Various antibacterial coating technologies have proven to be safe and effective both in preclinical and clinical studies, with post-surgical implant-related infections reduced by 90% in some cases, depending on the type of coating and experimental setup used. Economic assessment may enable the cost-to-benefit profile of any given antibacterial coating to be defined, based on the expected infection rate with and without the coating, the cost of the infection management, and the cost of the coating. After reviewing the latest evidence on the available antibacterial coatings, we quantified the impact caused by delaying their large-scale application. Considering only joint arthroplasties, our calculations indicated that for an antibacterial coating, with a final user’s cost price of €600 and able to reduce post-surgical infection by 80%, each year of delay to its large-scale application would cause an estimated 35 200 new cases of post-surgical infection in Europe, equating to additional hospital costs of approximately €440 million per year. An adequate reimbursement policy for antibacterial coatings may benefit patients, healthcare systems, and related research, as could faster and more affordable regulatory pathways for the technologies still in the pipeline. This could significantly reduce the social and economic burden of implant-related infections in orthopaedics and trauma. Cite this article: C. L. Romanò, H. Tsuchiya, I. Morelli, A. G. Battaglia, L. Drago. Antibacterial coating of implants: are we missing something? Bone Joint Res 2019;8:199–206. DOI: 10.1302/2046-3758.85.BJR-2018-0316

An increasing elderly population means joint replacement surgery numbers are projected to increase, with associated complications such as periprosthetic joint infections (PJI) also rising. PJI are particularly challenging due to antimicrobial resistant biofilm development on implant surfaces and surrounding tissues, with treatment typically involving invasive surgeries and systemic antibiotic delivery. Consequently, functionalisation of implant surfaces to prevent biofilm formation is a major research focus. This study characterises clinically relevant antimicrobials including gentamicin, clindamycin, daptomycin, vancomycin and caspofungin within a silica-based, biodegradable sol-gel coating for prosthetic devices. Antimicrobial activity of the coatings against clinically relevant microorganisms was assessed via disc diffusion assays, broth microdilution culture methods and the MBEC assay used to determine anti-biofilm activity. Human and bovine cells were cultured in presence of antimicrobial sol-gel to determine cytotoxicity using Alamar blue and antibiotic release was measured by LC-MS. Biodegradability in physiological conditions was assayed by FT-IR, ICP-MS and measuring mass change. Effect of degradation products on osteogenesis were studied by culturing mesenchymal stem cells in the presence of media in which sol-gel samples had been immersed. Antimicrobial-loaded coatings showed strong activity against a wide range of clinically relevant bacterial and fungal pathogens with no loss of activity from antibiotic alone. The sol-gel coating demonstrated controlled release of antimicrobials and initial sol-gel coatings showed no loss of viability on MSCs with gentamicin containing coatings. Current work is underway investigating cytotoxicity of sol-gel compositions against MG-63 cells and primary osteoblasts. This research forms part of an extended study into a promising antimicrobial delivery strategy to prevent PJI. The implant coating has potential to advance PJI infection prevention, reducing future burden upon healthcare costs and patient wellbeing

Failure of osseointegration and periprosthetic joint infection (PJI) are the two main reasons of implant failure after total joint replacement (TJR). Nanofiber (NF) implant surface coating represents an alternative local drug eluting device that improves osseointegration and decreases the risk of PJI. The purpose of this study was to investigate the therapeutic efficacies of erythromycin (EM)-loaded coaxial PLGA/PCL-PVA NF coating in a rat S. aureus-infected tibia model. NF coatings with 100mg and 1000mg EM were prepared. NF without EM was included as positive control. 56 Sprague Dawley rats were divided into 4 groups. A titanium pin (1.0-mm x 8 mm) was placed into the tibia through the intercondylar notch. S. aureus (SA) was introduced by both direct injection of 10 μl broth (1 × 10. 4. CFU) into the medullary cavity and single dip of Ti pins into a similar solution prior to insertion. Rats were sacrificed at 8 and 16 weeks after surgery. The outcome measurements include μCT based quantitative osteolysis evaluation and hard tissue histology. Results: EM-NF coating (EM100 and EM1000) reduced osteolysis at 8 and 16 weeks, compared to EM0 and negative control. The effective infection control by EM-NFs was further confirmed by hard tissue section analysis. The Bone implant contact (BIC) and bone area fraction Occupancy (BAFO) within 200 µm of the surface of the pins were used to evaluate the osseointegration and new bone formation around the implants. At 16 weeks, the bone implant contact (BIC) of EM 100 (35.08%) was higher than that of negative control (3.43%) and EM0 (0%). The bone area fraction occupancy within 200 µm (BAFO) of EM100 (0.63 mm2) was higher than that of negative control (0.390 mm2) and EM0 (0.0 mm. 2. ). The BAFO of EM100 was also higher than that of EM1000 (0.3mm. 2. ). There was much less osteolysis observed with EM100 and EM1000 NF coatings at 16 weeks, as compared to EM0 positive control, p=0.08 and p=0.1, respectively. Osseointegration and periprosthetic bone formation was enhanced by EM-NFs, especially EM100. Data from this pilot study is promising for improving implant surface fabrication strategies

Infection of implanted medical devices (biomaterials), like titanium orthopaedic implants, can have disastrous consequences, including removal of the device. These so-called biomaterial-associated infections (BAI) are mainly caused by Staphylococcus aureus and Staphylococcus epidermidis. To prevent biofilm formation using a non-antibiotic based strategy, we aimed to develop a novel permanently fixed antimicrobial coating for titanium devices based on stable immobilized quaternary ammonium compounds (QACs). Medical grade titanium implants were dip-coated in subsequent solutions of hyperbranched polymer, polyethyleneimine and 10 mM sodium iodide, and ethanol. The QAC-coating was characterized using water contact angle measurements, scanning electron microscopy, FTIR, AFM and XPS. The antimicrobial activity of the coating was evaluated against S. aureus strain JAR060131 and S. epidermidis strain ATCC 12228 using the JIS Z 2801:2000 surface microbicidal assay. Lastly, we assessed the in vivo antimicrobial activity in a mouse subcutaneous implant infection model with S. aureus administered locally on the QAC-coated implants prior to implantation to mimic contamination during surgery. Detailed material characterization of the titanium samples showed the presence of a homogenous and stable coating layer at the titanium surface. Moreover, the coating successfully killed S. aureus and S. epidermidis in vitro. The QAC-coating strongly reduced S. aureus colonization of the implant surface as well as of the surrounding tissue, with no apparent macroscopic signs of toxicity or inflammation in the peri-implant tissue at 1 and 4 days after implantation. An antimicrobial coating with stable quaternary ammonium compounds on titanium has been developed which holds promise to prevent BAI. Non-antibiotic-based antimicrobial coatings have great significance in guiding the design of novel antimicrobial coatings in the present, post-antibiotic era. Acknowledgements: This research was financially supported by the Health∼Holland/LSH-TKI call 2021–2022, project 25687, NACQAC: ‘Novel antimicrobial coatings with stable non-antibiotic Quaternary Ammonium Compounds and photosensitizer technology'

Aim. The use of medical devices has grown significantly over the last decades, and has become a major part of modern medicine and our daily life. Infection of implanted medical devices (biomaterials), like titanium orthopaedic implants, can have disastrous consequences, including removal of the device. For still not well understood reasons, the presence of a foreign body strongly increases susceptibility to infection. These so-called biomaterial-associated infections (BAI) are mainly caused by Staphylococcus aureus and Staphylococcus epidermidis. Formation of biofilms on the biomaterial surface is generally considered the main reason for these persistent infections, although bacteria may also enter the surrounding tissue and become internalized within host cells. To prevent biofilm formation using a non-antibiotic based strategy, we aimed to develop a novel permanently fixed antimicrobial coating for titanium devices based on stable immobilized quaternary ammonium compounds (QACs). Method. Medical grade titanium implants (10×4×1 mm) were dip-coated in a solution of 10% (w/v) hyperbranched polymer, subsequently in a solution of 30% (w/v) polyethyleneimine and 10 mM sodium iodide, using a dip-coater, followed by a washing step for 10 min in ethanol. The QAC-coating was characterized using water contact angle measurements, scanning electron microscopy, FTIR, AFM and XPS. The antimicrobial activity of the coating was evaluated against S. aureus strain JAR060131 and S. epidermidis strain ATCC 12228 using the JIS Z 2801:2000 surface microbicidal assay. Lastly, we assessed the in vivo antimicrobial activity in a mouse subcutaneous implant infection model with S. aureus administered locally on the QAC-coated implants prior to implantation to mimic contamination during surgery. Results. Detailed material characterization of the titanium samples showed the presence of a homogenous and stable coating layer at the titanium surface. Moreover, the coating successfully killed S. aureus and S. epidermidis in vitro. The QAC-coating strongly reduced S. aureus colonization of the implant surface as well as of the surrounding tissue, with no apparent macroscopic signs of toxicity or inflammation in the peri-implant tissue at 1 and 4 days after implantation. Conclusions. An antimicrobial coating with stable quaternary ammonium compounds on titanium has been developed which holds promise to prevent BAI. Non-antibiotic-based antimicrobial coatings have great significance in guiding the design of novel antimicrobial coatings in the present, post-antibiotic era

ZrN-multilayer coating is clinically well established in total knee arthroplasty [1-3] and has demonstrated significant reduction in polyethylene wear and metal ion release [4,5]. The goal of our study was to analyze the biotribological behaviour of the ZrN-multilayer coating on a polished cobalt-chromium cemented hip stem. CoCr28Mo6 alloy hip stems with ZrN-multilayer coating (CoreHip®AS) were tested versus an un-coated version. In a worst-case-scenario the stems with ceramic heads have been tested in bovine serum in a severe cement interface debonding condition under a cyclic load of 3,875 N for 15 million cycles. After 1, 3, 5, 10 & 15 million cycles the surface texture was analysed by scanning-electron-microscopy (SEM) and energy-dispersive x-ray (EDX). Metal ion concentration of Co,Cr,Mo was measured by inductively coupled plasma mass spectroscopy (ICP-MS) after each test interval. Based on SEM/EDX analysis, it has been demonstrated that the ZrN-multilayer coating keeps his integrity over 15 million cycles of severe stem cemented interface debonding without any exposure of the CoCr28Mo6 substrate. The ZrN-multilayer coated polished cobalt-chromium cemented hip stem has shown a reduction of Co & Cr metal ion release by two orders of a magnitude, even under severe stem debonding and high interface micro-motion conditions. ZrN-multilayer coating on polished cobalt-chromium cemented hip stems might be a suitable option for further minimisation of Co & Cr metal ion release in total hip arthroplasty. Clinical evidence has to be proven during the next years

Device-associated bacterial infections are a major and costly clinical challenge. This project aimed to develop a smart new biomaterial for implants that helps to protect against infection and inflammation, promote bone growth, and is biodegradable. Gallium (Ga) doped strontium-phosphate was coated on pure Magnesium (Mg) through a chemical conversion process. Mg was distributed in a graduated manner throughout the strontium-phosphate coating GaSrPO4, with a compact structure and a Ga-rich surface. We tested this sample for its biocompatibility, effects on bone remodeling and antibacterial activities including Staphylococcus aureus, S. epidermidis and E. coli - key strains causing infection and early failure of the surgical implantations in orthopaedics and trauma. Ga was distributed in a gradient way throughout the entire strontium-phosphate coating with a compact structure and a gallium-rich surface. The GaSrPO4 coating protected the underlying Mg from substantial degradation in minimal essential media at physiological conditions over 9 days. The liberated Ga ions from the coatings upon Mg specimens inhibited the growth of bacterial tested. The Ga dopants showed minimal interferences with the SrPO4 based coating, which boosted osteoblasts and undermined osteoclasts in in vitro co-cultures model. The results evidenced this new material may be further translated to preclinical trial in large animal model and towards clinical trial. Acknowledgements: Authors are grateful to the financial support from the Australian Research Council through the Linkage Scheme (ARC LP150100343). The authors acknowledge the facilities, and the scientific and technical assistance of the RMIT University and John Curtin School of Medical Research, Australian National University

Aim. To develop a new system for antibacterial coating of joint prosthesis and osteosynthesis material. The new coating system was designed to release gentamicin immediately after insertion to eradicate surgical contamination. Method. Steel implants (2×15mm) were coated with a solid nanocomposite xerogel made from silica and the dendritic polymer, hyperbranched polyethyleneimine. The xerogel was anchored inside a porous surface made by pre-coating with titanium microspheres. Finally, gentamicin was encapsulated in the xerogel, i.e. no chemical binding. A total of 50 µg gentamicin was captured into each implant. The efficacy of the new coating was evaluated in a porcine model of implant associated osteomyelitis. In total, 30 female pigs were randomized into 3 study groups (n=10). Group A; plain implants + saline, Group B; plain implants + 10. 4. CFU of Staphylococcus aureus, and Group C; coated implants + 10. 4. CFU of S. aureus. Implant + inoculum was placed into a pre-drilled implant cavity of the right tibia and the pig was euthanized 5 days afterwards. Postmortem microbiology and pathology were performed. Two additional pigs were used in a pharmacokinetic study where microdialysis (MD) catheters were placed alongside coated implants. Extracellular fluid was sampled regularly for 24 hours from the MD catheters and analyzed for gentamicin content. Results. Within Groups A and C, all implants were found sterile by sonication and bacteria could not be identified within the surrounding bone tissue. In contrast, all Group B animals had S. aureus positive implant and tissue microbiology. Macroscopic and microscopic pathological examinations confirmed that Group A and C animals were complete identic, i.e. no pus around implants and only minor peri-implant inflammation related to insertion of implants per se. All Group B animals had pus around their implants and a massive peri-implant inflammatory response dominated by neutrophil granulocytes. Maximum gentamicin release (35 µg /mL) was measured in the first obtained MD sample, i.e. after 30 min, and the concentration stayed above the MIC level for the used S. aureus strain for 8 hours. Conclusions. The new xerogel coating prevented development of osteomyelitis. Prevention was due to a fast gentamicin release immediately following insertion and antimicrobial active concentrations were detectable several hours after implantation. This means that the critical time point of most relevant surgical procedures potentially could be protected by the novel coating. The new coating will be investigated on larger scale implants and full-size prosthesis in the future

Aims. The aim of this study was to develop a single-layer hybrid organic-inorganic sol-gel coating that is capable of a controlled antibiotic release for cementless hydroxyapatite (HA)-coated titanium orthopaedic prostheses. Methods. Coatings containing gentamicin at a concentration of 1.25% weight/volume (wt/vol), similar to that found in commercially available antibiotic-loaded bone cement, were prepared and tested in the laboratory for: kinetics of antibiotic release; activity against planktonic and biofilm bacterial cultures; biocompatibility with cultured mammalian cells; and physical bonding to the material (n = 3 in all tests). The sol-gel coatings and controls were then tested in vivo in a small animal healing model (four materials tested; n = 6 per material), and applied to the surface of commercially pure HA-coated titanium rods. Results. The coating released gentamicin at > 10 × minimum inhibitory concentration (MIC) for sensitive staphylococcal strains within one hour thereby potentially giving effective prophylaxis for arthroplasty surgery, and showed > 99% elution of the antibiotic within the coating after 48 hours. There was total eradication of both planktonic bacteria and established bacterial biofilms of a panel of clinically relevant staphylococci. Mesenchymal stem cells adhered to the coated surfaces and differentiated towards osteoblasts, depositing calcium and expressing the bone marker protein, osteopontin. In the in vivo small animal bone healing model, the antibiotic sol-gel coated titanium (Ti)/HA rod led to osseointegration equivalent to that of the conventional HA-coated surface. Conclusion. In this study we report a new sol-gel technology that can release gentamicin from a bioceramic-coated cementless arthroplasty material. In vitro, local gentamicin levels are in excess of what can be achieved by antibiotic-loaded bone cement. In vivo, bone healing in an animal model is not impaired. This, thus, represents a biomaterial modification that may have the potential to protect at-risk patients from implant-related deep infection. Cite this article: Bone Joint J 2021;103-B(3):522–529

Musculoskeletal disorders is one of most important health problems human population is facing includes. Approximately 310 thousand of hip protheses have been used in 45 years and older patients in total according to the recent studies have been done. [1, 2]. Many factors, including poor osseointegration or relaxation of the implant due to stress, limit the life of the load-bearing implants [3]. To overcome these difficulties and to protect metal implants inside the body, the surfaces of the implants were coated with silver ion doped hydroxyapatite/bioglass. In this study, silver doped hydroxyapatite ceramic powder and 6P57 bioglass were synthesized. Two different coating suspensions, 100% bioglass and 70% Ag-HAp / 30% bioglass, were prepared in methyl alcohol with a solid content of 1% by weight. Two layers were coated on the external fixator nails by using electrospray method with the bioglass and Ag-Hap/Bioglass suspensions respectively. The coated implants were cut with an equal surface area and kept in human blood plasma for different time. The scanning electron microscopy (SEM, Zeiss Supra 50VP and Zeiss Evo 50EP) and stereo microscope (Zeiss Axiocam Stemi 2000-C) were used to characterize microstructure and thickness of coated surface. Energy dispersive X-ray Spectroscopy was used characterized of chemical composition of coating. Changing of pH value of plasma was measured by pH meter (Hanna HI83414). In addition, the ICP method was used to determine the elements contained in the plasma fluid after dissolution. As a result of this study, physical and chemical changes occurring on the coating surface in different time periods are presented in detail

Introduction. To evaluate the effect of hydroxyapatite coating, two same shape cementless stems were compared in this randomized control trial study. Methods. Between May 2003 and February 2010, 88 patients had a primary cementless total hip arthroplasty with two different types of cementless stems. Forty-three patients had Proarc stems (P group) (Kyocera Medical, Osaka, Japan), and Forty-five patients had Proarc HA stems (HA group) (Kyocera Medical, Osaka, Japan) which was coated with thin (20 micrometer) hydroxyapatite on Proarc rough porous coating. Gender distribution, average age at surgery, average weight and average follow-up period were same in the two groups. The average follow-up period was 8.5 years (range, 5 to 13 years). The average age at the time of surgery was 63 years. Porous acetabular shells and highly crosslinked polyethylene liners made by Kyocera Medical corporation were implanted into all hips. Stems were implanted with a modified Hardinge surgical approach without trochanteric osteotomy. Harris Hip Score was used for clinical evaluation. Post-op radiographs of these patients were evaluated. Fisher's exact probability test was used for statistical analysis. P values of less than 0.05 were considered to be significant. Results. The mean preoperative score and postoperative score of P group were 39 points and 86 points, respectively. The mean preoperative score and postoperative score of HA group were 46 points and 87 points, respectively. All stems were evaluated as bone-ingrown fixation in both groups. The rate of varus inclination was not different between two groups. The rate of severe stress shielding was not different. Discussion. However hydroxyapatite coating is useful for early fixation, the adverse effect, such as delamination for long-term in vivo situation is questionable. There was no significant difference between P-group and HA group in the present study. Longer follow-up is required to evaluate hydroxyapatite coating

Aims. Periprosthetic joint infection (PJI) is a debilitating condition with a substantial socioeconomic burden. A novel autologous blood glue (ABG) has been developed, which can be prepared during surgery and sprayed onto prostheses at the time of implantation. The ABG can potentially provide an antimicrobial coating which will be effective in preventing PJI, not only by providing a physical barrier but also by eluting a well-known antibiotic. Hence, this study aimed to assess the antimicrobial effectiveness of ABG when impregnated with gentamicin and stem cells. Methods. Gentamicin elution from the ABG matrix was analyzed and quantified in a time-dependent manner. The combined efficiency of gentamicin and ABG as an anti-biofilm coating was investigated on titanium disks. Results. ABG-gentamicin was bactericidal from 10 μg/ml and could release bactericidal concentrations over seven days, preventing biofilm formation. A concentration of 75 μg/ml of gentamicin in ABG showed the highest bactericidal effect up to day 7. On titanium disks, a significant bacterial reduction on ABG-gentamicin coated disks was observed when compared to both uncoated (mean 2-log reduction) and ABG-coated (mean 3-log reduction) disks, at days 3 and 7. ABG alone exhibited no antimicrobial or anti-biofilm properties. However, a concentration of 75 μg/ml gentamicin in ABG sustains release over seven days and significantly reduced biofilm formation. Its use as an implant coating in patients with a high risk of infection may prevent bacterial adhesion perioperatively and in the early postoperative period. Conclusion. ABG’s use as a carrier for stem cells was effective, as it supported cell growth. It has the potential to co-deliver compatible cells, drugs, and growth factors. However, ABG-gentamicin’s potential needs to be further justified using in vivo studies. Cite this article: Bone Joint Res 2020;9(12):848–856

Intraneural electrodes can be harnessed to control neural prosthetic devices in human amputees. However, in chronic implants we witness a gradual loss of device functionality and electrode isolation due to a nonspecific inflammatory response to the implanted material, called foreign body reaction (FBR). FBR may eventually lead to a fibrous encapsulation of the electrode surface. Poly(ethylene glycol) (PEG) is one of the most common low-fouling materials used to coat and protect electrode surfaces. Yet, PEG can easily undergo encapsulation and oxidative damage in long-term in vivo applications. Poly(sulfobetaine methacrylate) - poly(SBMA) - zwitterionic hydrogels may represent more promising alternatives to minimize the FBR due to their ultra-low fouling features. Here, we tested and compared the poly(SBMA) zwitterionic hydrogel coating with the PEG coating in reducing adhesion and activation of pro-inflammatory and pro-fibrotic cells to polyimide surfaces, which are early hallmarks of FBR. We aimed to coat polyimide surfaces with a hydrogel thin film and analysed the release of a model drug from the hydrogel. We performed hydrogel synthesis, mechanical characterization and biocompatibility analysis. Cell adhesion, viability and morphology of human myofibroblasts cultured on PEG- and hydrogel-coated surfaces were evaluated through confocal microscopy-based high-content analysis (HCA). Reduced activation of pro-inflammatory human macrophages cultured on hydrogels was assessed as well as the hydrogel drug release profile. Because of its high hydration, biocompatibility, low stiffness and ultra-low fouling characteristics the hydrogel enabled lower adhesion and activation of pro-inflammatory and pro-fibrotic cells vs. polystyrene controls, and showed a long-term release of the anti-fibrotic drug Everolimus. Furthermore, a polyimide surface was successfully coated with a hydrogel thin film. Our soft zwitterionic hydrogel could outperform PEG as more suitable coating material of neural electrodes for mitigating the FBR. Such poly(SBMA)-based biomaterial could also be envisioned as long-term delivery system for a sustained release of anti-inflammatory and anti-fibrotic drugs in vivo

Orthopaedic and trauma implant related infection remains one of the major complications that negatively impact clinical outcome and significantly increase healthcare expenditure. Hydroxyapatite has been used for many years to increase implant osseointegration. Silver has been introduced into hydroxyapatite as an antimicrobial coating for orthopedic implants. This surface coatings can both increase tissue compatibility and prevent implant-related infections. We examined infection markers and blood silver values, liver and kidney function tests of 30 patients with of three groups of orthopedic implants, external fixators, intramedullary nails and hip replacements, coated with Ag + ion doped CaP based ceramic powder to determine safety and effectiveness of this dual-function coating. During 1 year follow-up, the pin sites were observed at the external fixator group, and wound areas for the proximal femoral nail and hip arthroplasty group at regular intervals. In addition, liver and kidney function tests, infection markers and blood silver values were checked in patients. In the external fixator group, only 4 out of 91 pin sites (%4.39) were infected. The wound areas healed without any problem in patients with proximal femoral nails and hip arthroplasty. There was no side effect suggesting silver toxicity such as systemic toxic side effect or argyria in any patient and blood silver level did not increase. Compared to similar patient groups in the literature, much lower infection rates were obtained (p = 0.001), and implant osseointegration was good. In patients with chronic infection, the implants were applied acutely after removing the primary implant and with simple debridement. Unlike other silver coating methods, silver was trapped in hydroxyapatite crystals in the ionic form, which is released from the coating during the process of osseointegration, thus, the silver was released into the systemic circulation gradually that showed antibacterial activity locally. We conclude that the use of orthopedic implants with a silver ion added calcium phosphate-based special coating is a safe method to prevent the implant-related infection. This work was supported by TUBİTAK Project Number 315S101

A silver-containing hydroxyapatite (Ag-HA) coating has been developed using thermal spraying technology. We evaluated the osteoconductivity of this coating on titanium (Ti) implants in rat tibiae in relation to bacterial infection in joint replacement. At 12 weeks, the mean affinity indices of bone formation of a Ti, an HA, a 3%Ag-HA and a 50%Ag-HA coating were 97.3%, 84.9%, 81.0% and 40.5%, respectively. The mean affinity indices of bone contact of these four coatings were 18.8%, 83.7%, 77.2% and 40.5%, respectively. The indices of bone formation and bone contact around the implant of the 3%Ag-HA coating were similar to those of the HA coating, and no significant differences were found between them (bone formation, p = 0.99; bone contact, p = 0.957). However, inhibition of bone formation was observed with the 50%Ag-HA coating. These results indicate that the 3%Ag-HA coating has low toxicity and good osteoconductivity, and that the effect of silver toxicity on osteoconductivity depends on the dose

Objectives. An experimental rabbit model was used to test the null hypothesis, that there is no difference in new bone formation around uncoated titanium discs compared with coated titanium discs when implanted into the muscles of rabbits. Methods. A total of three titanium discs with different surface and coating (1, porous coating; 2, porous coating + Bonemaster (Biomet); and 3, porous coating + plasma-sprayed hydroxyapatite) were implanted in 12 female rabbits. Six animals were killed after six weeks and the remaining six were killed after 12 weeks. The implants with surrounding tissues were embedded in methyl methacrylate and grinded sections were stained with Masson-Goldners trichrome and examined by light microscopy of coded sections. Results. Small amounts of bone were observed scattered along the surface of five of the 12 implants coated with porous titanium, and around one out of 12 porous coated surfaces with Bonemaster. No bone formation could be detected around porous coated implants with plasma-sprayed hydroxyapatite. Conclusion. Porous titanium coating is to some degree osteoinductive in muscles

Introduction. Although cementless press-fit femoral total knee arthroplasty (TKA) components are routinely used in clinical practice, the effect of the interference fit on primary stability is still not well understood. Intuitively, one would expect that a thicker coating and a higher surface roughness lead to a superior fixation. However, during implant insertion, a thicker coating can introduce more damage to the underlying bone, which could adversely influence the primary fixation. Therefore, in the current study, the effect of coating thickness and roughness on primary stability was investigated by measuring the micromotions at the bone-implant interface with experimental testing. Methods. A previous experimental set-up was used to test 6 pairs of human cadaveric femurs (47–60 years, 5 females) implanted with two femoral component designs with either the standard e.motion (Total Knee System, B. Braun, Germany) interference fit of 350 µm (right femurs) or a novel, thicker interference fit of 700 µm (left femurs). The specimens were placed in a MTS machine (Figure 1) and subjected to the peak loads of normal gait (1960N) and squat (1935N), based on the Orthoload dataset for Average 75. Varus/valgus moments were incorporated by applying the loads at an offset relative to the center of the implants, leading to a physiological mediolateral load distribution. Under these loads, micromotions at the implant-bone interface were measured using Digital Image Correlation (DIC) at different regions of interest (ROIs – Figure 1). In addition, DIC was used to measure opening and closing of the implant-bone interface in the same ROIs. Results. After comparing the micromotions and opening of the two implant designs, we found no significant differences between the standard and novel coating. Loading was a significant factor for both opening (P<0.0001) and micromotions (P=0.019), where the squat produced higher micromotions than gait. Opening was seen anteriorly (MA, LA), and was higher during squat. Closing was noticed distally (MD, LD), particularly during gait (Figure 2). During gait (Figure 3), the highest micromotions were found in the posterior condyles (CM, MP), followed by the medial anterior region (MA). For squat, the largest micromotions were in the anterior flange (ANT), followed by the distal regions (LD, MD). Discussion. In the current study, the primary stability of the same implant with two different coating thicknesses was evaluated. The results demonstrate that increasing the coating thickness does not automatically influence the primary stability of a femoral TKA component. This is likely due to abrasion and damage of the underlying trabecular during implant insertion, which also was observed in previous experiments. The exact relation between coating thickness or interference fit and primary implant stability still remains subject to debate. Obviously, the primary implant stability is compromised when the interference fit is too low. However, the current results suggest that there is a threshold beyond which further improvement of the fixation is not possible. The exact magnitude of this threshold is unknown, and may depend on coating characteristics and bone quality, and requires further evaluation, possibly utilizing a hybrid approach of experimental and computational techniques

Uncemented implants combining antimicrobial properties with osteoconductivity would be highly desirable in revision surgery due to periprosthetic joint infection (PJI). Silver coatings convey antibacterial properties, however, at the cost of toxicity towards osteoblasts. On the other hand, topological modifications such as increased surface roughness or porosity support osseointregation but simultaneously lead to enhanced bacterial colonization. In this study, we investigated the antibacterial and osteoconductive properties of silver-coated porous titanium (Ti) alloys manufactured by electron beam melting, rendering a macrostructure that mimics trabecular bone. Trabecular implants with silver coating (TR-Ag) or without coating (TR) were compared to grit-blasted Ti6Al4V (GB) and glass cover slips as internal controls. Physicochemical characterization was performed by X-ray diffraction (XRD) and energy dispersive X-rays (EDX) together with morphological characterization through electron scanning microscopy (SEM). Bacterial adherence after incubation of samples with Staphylococcus (S.) aureus and S. epidermidis strains harvested from PJI patients was quantitatively assessed by viable count after detachment of adherent bacteria by collagenase/dispase treatment. Primary human osteoblasts (hOB) were used to investigate the osteoconductive potential by lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) activity. Cell morphology was investigated by fluorescence microscopy after staining with carboxifluorescein diacetate succinimidyl ester (CFDA-SE) and 4′,6-diamidino-2-phenylindole (DAPI). The trabecular implants depicted a porosity of 70% with pore sizes of 600µm. The amount of silver analyzed by EDX accounted for 35%wt in TR-Ag but nil in TR. Silver-coated TR-Ag implants had 24% lower S. aureus viable counts compared to non-coated TR analogues, and 9% lower compared to GB controls. Despite trabecular implants, both with and without silver, had higher viable counts than GB, the viable count of S. epidermidis was 42% lower on TR-Ag compared to TR. The percentage of viable hOB, measured by LDH and normalized to controls and area at 1 day, was lower on both TR-Ag (18%) and on TR (13%) when compared with GB (89%). However, after 1 week, cell proliferation increased more markedly on trabecular implants, with a 5-fold increase on TR-Ag, a 3.4-fold increase on TR, and a 1.7-fold increase on GB. Furthermore, after 2 weeks of hOB culture, proliferation increased 20-fold on TR-Ag, 29-fold on TR, and 3.9-fold for GB, compared to 1 day. The osteoconductive potential measured by ALP illustrated slightly higher values for TR-Ag compared to TR at 1 day and 2 weeks, however below those of GB samples. Cell morphology assessed by microscopy showed abundant growth of osteoblast-like cells confined to the pores of TR-Ag and TR. Overall, our findings indicate that the silver coating of trabecular titanium exerts limited cytotoxic effects on osteoblasts and confers antimicrobial effects on two PJI-relevant bacterial strains. We conclude that improving material design by mimicking the porosity and architecture of cancellous bone can enhance osteoconductivity while the deposition of silver confers potent antimicrobial properties

This study aimed to verify the hypothesis that an antibiotic loaded hydrogel, defensive antimicrobial coating (DAC), reduces overall complication and infection rates when used for high-risk primary and revision total hip arthroplasty (THA). This was a retrospective study matched cohort study of 238 patients, treated with cementless implants with and without DAC. A sub-group analysis of patients undergoing 2nd stage revision THA for prosthetic joint infection (PJI) was also conducted. Re-infection rates within 2 years, complications necessitating surgical intervention and radiographic analysis for aseptic loosening was assessed. The mean age was 68.3±11.5 years, with 39 (32.8%) Macpherson class A, 64 (53.8%) class B and 16 (13.4%) class C patients. 4 (3.4%) patients in the DAC group developed complications including 1 PJI and 1 delayed wound healing, while 13 (10.9%) patients in the control group developed complications including 5 PJIs and 3 delayed wound healing (p=0.032). PJI rates (p=0.136) and delayed wound healing rates (p=0.337) were not statistically significant. For 2nd stage revision THA for PJI there were 86 patients in the DAC group and 45 in the control group. 1 (1.2%) patient in the DAC group developed complications with no recurrences of infection or delayed wound healing, while 10 (22.2%) patients in the control group developed complications including 4 recurrent PJI and 1 delayed wound healing (p=0.003). Recurrent PJI rates were statistically significant (p=0.005) while delayed wound healing rates were not (p=0.165). Patients treated with DAC also had lower rates of aseptic loosening (0% vs 6.7%; p=0.015). Antibiotic impregnated hydrogel coatings on cementless implants showed decreased complication rates after complex primary or revision THA. In 2nd stage revision THA for PJI, it was associated with reduced risk of re-infection and aseptic loosening

Introduction. Cobalt chrome femoral head has been used widely in total hip arthroplasty and has shown favorable outcome. However, there is still of concern of potential metal toxicity from the wear debris. In the other hand, titanium is well known for its biocompatibility but it is not used in bearing surface of arthroplasty due to its brittleness. Recently, coating of the prosthesis using plasma electrolytic oxidation (PEO) has shown favorable surface protection. Thus, in this study, we tried to find out whether the PEO coating on the titanium surface would provide surface protection. Materials and methods. Five Titanium alloy (Ti-6Al-4V) ball mimicking femoral head was manufactured and was coted using plasma electrolytic oxidation. Wear rate was tested using validated wear tester with 10N compression force at 80rpm. The amount of wear was detected by measuring change of weight after wear test was completed. This was compared with femoral head manufactured with titanium alloy without PEO coating. Toxicity of the debris was also tested using MTT assay with human osteoblast cell line. Results. Compare to the base titanium metal, PEO coated metal head has shown to provide surface protection. The wear rate has significantly decreased with PEO coating (median value : 0.00015g/mm. 2. vs 0.00006 g/mm. 2. ). MTT assay revealed no cytotoxicity with the amount of debris generated from the wear test. Conclusion. The result of the current study indicate that the PEO coating on the titanium femoral head can significantly decrease the wear rate and is non cytotoxic. This indicates that the femoral head manufactured with titanium alloy and PEO coating maybe a potential alternative to be used in total hip arthroplasty

Preventing infections in joint replacements is a major ongoing challenge, with limited effective clinical technologies currently available for uncemented knee and hip prostheses. This research aims to develop a coating for titanium implants, consisting of a supported lipid bilayer (SLB) encapsulating an antimicrobial agent. The SLB will be robustly tethered to the titanium using self-assembled monolayers (SAMs) of octadecylphosphonic acid (ODPA). The chosen antimicrobial is Novobiocin, a coumarin-derived antibiotic known to be effective against resistant strains of Staphylococcus aureus. ODPA SAMs were deposited on TiO. 2. -coated quartz crystal microbalance (QCM) sensors using two environmentally friendly non-polar solvents (anisole and cyclopentyl methyl ether, CPME), two concentrations of ODPA (0.5mM and 1mM) and two processing temperatures (21°C and 60°C). QCM, water contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and temperature-programmed desorption mass spectrometry (TPD-MS) were used to characterise the ODPA SAM. A SLB with encapsulated Novobiocin was subsequently developed on the surface of the ODPA SAM using fluorescent lipids and a solvent assisted method. The prototype implant surface was tested for antimicrobial activity against S. aureus. A well-ordered, uniform ODPA SAM was rapidly formed using 0.5 mM ODPA in CPME at 21°C during 10 min, as confirmed by high Sauerbrey mass (≍285-290 ng/cm. 2. ), high atomic percentage phosphorus (detected using XPS) and high water contact angles (117.6±2.5°). QCM measurements combined with fluorescence microscopy provided evidence of complete planar lipid bilayer formation on the titanium surface using a solvent assisted method. Incorporation of Novobiocin into the SLB resulted in reduced attachment and viability of S. aureus. Key parameters were established for the rapid, robust and uniform formation of an ODPA SAM on titanium (solvent, temperature and concentration). This allowed the successful formation of an antimicrobial SLB, which demonstrated potential for reducing attachment and viability of pathogens associated with joint replacement infections

Periprosthetic joint infections (PJIs) and osteosynthesis-associated infections (OSIs) present significant challenges in trauma and orthopaedic surgery, substantially impacting patient morbidity, mortality, and economic burden. This concern is heightened in patients with pre-existing comorbidities, such as diabetes mellitus, which are not always modifiable at presentation. A novel intraoperative strategy to prevent these infections is the use of Defensive Antibacterial Coating (DAC), a bio-absorbable antibiotic-containing hydrogel applied to implant surfaces at implantation, acting as a physical barrier to prevent infection. The purpose of this study is to assess the use of a commercially available hydrogel (DAC), highlighting its characteristics that make it suitable for managing PJIs and OSIs in orthopaedics and traumatology. Twenty-five patients who underwent complex orthopaedic procedures with intraoperative application of DAC between March 2022 and April 2023 at a single hospital site were included. Post-operative assessment encompassed clinical, laboratory, and radiographic examinations. In this study, 25 patients were included, with a mean age of 70 ± 14.77 years and an average ASA grade of 2.46 ± 0.78. The cohort presented an average Charleston Comorbidity score of 5.45 ± 2.24. The procedures included 8 periprosthetic fractures, 8 foot and ankle surgeries, 5 upper limb surgeries, and 4 elective hip and knee surgeries. Follow-up assessments at 6 weeks and 6 months revealed no evidence of PJI or OSI in any patients, nor were any treatments for PJI or OSI required during the interim period. DAC demonstrated efficacy in preventing infections in high-risk patients undergoing complex orthopaedic procedures. Our findings warrant further investigation into the use of DAC in complex hosts with randomized control trials

Invasive intraneural electrodes implanted in peripheral nerves are neural prosthetic devices that are exploied to control advanced neural-interfaced prostheses in human amputees. One of the main issues to be faced in chronic implants is represented by the gradual loss of functionality of such intraneural interfaces due to an electrical impedance increase caused by the progressive formation of a fibrotic capsule around the electrodes, which is originally due to a nonspecific inflammatory response called foreign body reaction (FBR). In this in vitro work, we tested the biocompatibility and ultra-low fouling features of the synthetic coating - poly(ethylene glycol) (PEG) - compared to the organic polymer - zwitterionic sulfated poly(sulfobetaine methacrylate) (SBMA) hydrogel - to prevent or reduce the first steps of the FBR: plasma protein adsorption and cell adhesion to the interface. Synthesis and characterization of the SBMA hydrogel was done. Preliminary biocompatibility analysis of the zwitterionic hydrogel, using hydrogel-conditioned medium, showed no cytotoxicity at all vs. control. We seeded GFP-labelled human myofibroblasts on PEG- and SBMA hydrogel-coated polyimide surfaces and evaluated their adhesion and cell viability at different time-points. Because of the high hydration, low stiffness reflecting the one of neural tissue, and ultra-low fouling characteristics of the SBMA hydrogel, this polymer showed lower myofibroblast adhesion and different cell morphology compared to adhesion controls, thereby representing a better coating than PEG for potentially mitigating the FBR. We conclude that soft SBMA hydrogels could outperform PEG coatings in vitro as more suitable dressings of intraneural electrodes. Furthermore, such SBMA-based antifouling materials can be envisioned as long-term diffusion-based delivery systems for controlled release of anti-inflammatory and anti-fibrotic drugs in vivo

Background. External fixation is a method of osteosynthesis currently required in traumatology and orthopaedic surgery. Pin tract infection is a common problem in clinical practice. Infection occurs after a bacterial colonisation of the pin due to its contact with skin and local environment. To prevent such local contamination, one way to handle this issue is to create a specific coating using method which could be applied in the medical field. In this work we develop a surface coating for external fixator pins based on photocatalytic TiOα properties, producing a bactericidal effect with sufficient mechanical strength to be compatible with surgical use. Method. The morphology and structure of the sol-gel coating layers were characterised using, respectively, scanning electron microscopy and X-ray diffraction. Resistance properties of the coating were investigated by mechanical testing. Photo-degradation of acid orange 7 in aqueous solution was used as a probe, to assess the photo-catalytic activity of titanium dioxide layers under UV irradiation. The bactericidal effect induced by the process was evaluated against 2 strains: a Staphylococcus aureus and a multiresistant Staphylococcus epidermidis. Results. The coated pins showed good mechanical strength and efficient antibacterial effect after 1 hour of UV irradiation. Conclusion. Our study allowed to develop an antibacterial coating for stainless steel commonly used in surgical practice. The process using photoactive TiO2 exposed to UV irradiation is actually well known and applied in many disinfection fields, and exhibited efficiency against the two main bactericidal strains involved in pin tract infections. Mechanical tests confirmed the coating's ability to resist to important stresses. Moreover, this kind of coating created by sol-gel dip-coating techniques is not expensive and quite easy to do. As a consequence, we can hope that this new option would treat preventively pin tract infection, even if there is an important optimisation task to be done in order to amplify bactericidal properties. Level of evidence. II

The success of long-term transcutaneous implants depends on dermal attachment to prevent downgrowth of the epithelium and infection. Hydroxyapatite (HA) coatings and fibronectin (Fn) have independently been shown to regulate fibroblast activity and improve attachment. In an attempt to enhance this phenomenon we adsorbed Fn onto HA-coated substrates. Our study was designed to test the hypothesis that adsorption of Fn onto HA produces a surface that will increase the attachment of dermal fibroblasts better than HA alone or titanium alloy controls. . Iodinated Fn was used to investigate the durability of the protein coating and a bioassay using human dermal fibroblasts was performed to assess the effects of the coating on cell attachment. Cell attachment data were compared with those for HA alone and titanium alloy controls at one, four and 24 hours. Protein attachment peaked within one hour of incubation and the maximum binding efficiency was achieved with an initial droplet of 1000 ng. We showed that after 24 hours one-fifth of the initial Fn coating remained on the substrates, and this resulted in a significant, three-, four-, and sevenfold increase in dermal fibroblast attachment strength compared to uncoated controls at one, four and 24 hours, respectively

Introduction: The present series of studies were performed in order to investigate the effect of hydroxyapatite coating on bone ingrowth into cementless implants when subjected to pathological and mechanical conditions mimicking the clinical situation. Material & methods and results: Hydroxyapatite (HA) and titanium alloy (Ti) coated implants were inserted into the femoral condyles in mature dogs. The observation period ranged between 4 and 16 weeks and the results were evaluated by mechanical push-out test and histomorphometric analysis. The HA coating yielded superior effect on bone ingrowth compared to Ti when surrounded by a gap-whereas no effect was found in the press fit situation. Allogeneic bone graft packed around the implant enhanced the anchorage of Ti implants, but HA coating alone without bone graft offered almost the same improvement in anchorage in 2 mm defects. Only minor improvement was obtained when bone graft was used together with hydroxyapatite. Another interesting study showed that HA coating was able to prevent polyethylene particles to migrate around the implant by creating a seal of bony ingrowth. HA coating on a porous surface resulted in significantly stronger fixation compared with HA coating on a grit blasted surface. A clinical study (using roentgen stereophotogrammetric analysis, RSA) on total hip arthroplasty showed that HA coated femoral components were stable 3 months after surgery whereas migration of Ti coated components continued resulting in significantly less migration of HA coated components at 60 months

Introduction. Cementless arthroplasty has been widely used for younger patients with osteoarthritis and other joint pathology. Cementless arthroplasty will be required to porous surface which is to similar to the trabecular bone for bone ingrowth. Titanium Plasma Spray (TPS) has been worldwide used for the porous coating method on arthroplasty. However, TPS coating is limited that would not to establish optimal porosity for bone ingrowth due to arbitary position of melted powder by plasma gas on substrate. Therefore, it is reported coating detached from its substrate (i.e. arthroplasty) is induced implant loosening. Thus, a novel Laser-aided Direct Metal Tooling (DMT) based on Additive Manufacturing (AM) was developed to overcome these limitations. In this study, we were done to assess stereological analysis, static tensile, shear, abrasion test, and physical analysis for evaluation of the efficacy of DMT which was newly-developed coating technology. Then, mechanical characteristics of DMT coating were compared to commercial TPS coating's. Materials and Methods. First, porosity of the DMT coating was evaluated using Microphotography and Scanning Electron Microscopy (SEM), as described in Figure 1. Static tensile and shear test for assessment of mechanical characteristic in relation to the DMT and TPS coating specimens were conducted on the basis of ASTM F1147 and F1044 using universal testing machine (Endolab®, Servohydraulic Test Frame, DE). Maximum tensile strength and maximum shear strength were evaluated for each specimen (n=5). Abrasion test was performed based on ASTM F1978 using Taber® Rotary Platform Abraser Model 5135 (TABER®Industries, USA). Abrasion losses for each specimen (n=6) were measured at 2, 5, 10, and 100 cycles, respectively. Results. Porosity of the DMT coating was found to be 64 ± 11%. Maximum tensile strength (mean ± SD) of the DMT coating (48.6 ± 4.3 MPa) was lower than TPS's (51.5 ± 11.6 MPa) about 5.6%, but detached position of one of the TPS specimens was observed at coating layer not in adhesive layer. Maximum shear strength of the DMT coating (46.3 ± 1.9 MPa) was 10.2% higher, compared to TPS's (42.0 ± 0.6 MPa). Abrasion losses of the DMT (2 cycles, 1.0 ± 0.5 mg; 5 cycles, 2.5 ± 0.9 mg; 10 cycles, 4.2 ± 0.7 mg; 100 cycles, 20 ± 1.4 mg) were significantly higher (71.9% – 77.8% higher) than that of TPS's (2 cycles, 4.5 ± 1.4 mg; 5 cycles, 9.8 ± 2.8 mg; 10 cycles, 17.0 ± 3.4 mg; 100 cycles, 71.1 ± 4.2 mg), as shown in Figure 2. Roughness of the DMT coating was Ra 62.5 ± 2 μm, Rz 316.1 ± 8.1 μm which were 33.5%, 40.6% (Ra, Rz sequence) higher than that of TPS coating (Ra 46.8 ± 8.9 μm, Rz 224.9 ± 28.8 μm), as shown in Figure 3. Conclusions. Our results suggested that a novel DMT coating technology was feasible to apply coating method on the surface of the arthroplasty in terms of outstanding mechanical characteristics which were compared to commercial TPS coating

The clinical outcome and radiographic analysis of 82 patients undergoing total hip arthroplasty using a titanium acetabular component coated with a new proprietary Titanium Porous Coating inserted without cement are reported. All total hip replacements were performed by a single surgeon and utilized a porous coated, cementless femoral component. Pre clinical testing was carried out in an animal model to evaluate the new porous coating. THR was performed using a cementless acetabular component of the same geometrical design inserted without cement. The component is coated with a new proprietary Titanium Porous Coating wherein the non-spherical bead itself is also porous. This creates a “lava rock” type of structure and gives variability in the pore sizes that aids in the in-growth and apposition of bone (fig 5). The inter-bead pore size: the pore size between each non-spherical bead = 200–525 μm while the Intra-bead pore size: the pore size within each non-spherical bead = 25–65 μm. The resulting surface is extremely rough and provides a robust initial “bite” or “stick” to the bone. Clinical results were evaluated using the Harris Hip score and were recorded prospectively preoperatively and at 6 weeks, 6 months, and 1 year postoperatively. Radiographs were evaluated for component migration, subsidence, and cortical and cancellous biologic response as well as zonal analysis of radiolucent lines, using the Muller THR template. Pre-clinical animal testing of the new porous coating was carried out in 50 sheep using a metacarpal intramedulary implant (similar to a hip stem) designed to function as a Percutaneous Osseointegrated Prosthesis (POP) for amputees and evaluated Apposition Bone Index (ABI) (fig 1), Mineral Apposition Rate (MAR) (fig 2),% Bone In-growth (fig 3), and Axial Pull-out Force (fig 4). Sheep were sacrificed at time points of 0, 3, 6, 9, and 12 months to measure and evaluate the above parameters. Human clinical and radiographic follow up averaged 10.5 months (range 2–18 months). There were 39 females and 43 males. Average age was 59 years. The clinical results were excellent with respect to both pain and function at mid term follow up. Patient satisfaction was high. Radiographic analysis showed no migration or change in the angle of inclination at latest follow up. Femoral component subsidence was detected in 2 cases and averaged 1.8 mm. No polyethylene wear was detected. No hips dislocated. No hips underwent additional surgery. Pre-clinical test data demonstrated excellent mechanical and biological attributes. Average tensile strength of the coating surpassed the FDA minimum requirement by 3X. Animal testing in the sheep showed no evidence of stem loosening or need for revision after 12 months, and corroborated well with clinical results. Correlation between the pre-clinical testing and the human experience was exceptional. Application of a new titanium porous coating utilizing a proprietary dual pore size structure to the surface of the acetabular component provides an extremely rough surface and robust initial fixation during cementless THR. Excellent early clinical and radiographic results are demonstrated. The addition of this new type of porous coating to other arthroplasty components may confer additional clinical advantages

Prosthetic joint infections (PJI) occur infrequently, but they represent the most devastating complication with high morbidity and substantial cost. Staphylococcus aureus are the most common infecting agents associated with acute PJI, and also appear in some cases of delayed PJI. 1. S. aureus biofilm development can be divided in two stages: adhesion and proliferation. 2. To avoid PJI bacterial adhesion has to be decreased. Hybrid organo-inorganic sol-gel coatings are proposed as a promising biomaterial improvement. 3. One of these compounds is a mixture of two organopolisiloxanes: 3-methacryloxypropyltrimethoxysilane (MAPTMS) and tetramethylorthosilicate (TMOS). The aim of this work was to evaluate bacterial adhesion on MAPTMS-TMOS coating compared to titanium parts made by powder metallurgy. MAPTMS-TMOS sol-gel coating was produced using a molar ratio of 1:2 (MAPTMS:TMOS) and dispersed in ethanol. The sol-gel was deposited by dip-coating on titanium parts made by powder metallurgy followed by a thermal treatment at 120 ºC for 30 minutes. 4. Titanium parts without sol-gel coating were used as control. S. aureus 15981 strain adherence study was performed using the protocol described by Kinnari et al. 5. with 90 min incubation. After incubation, the samples were stained with LIVE/DEAD BacLight Bacterial Viability Kit. Proportion of total adhered, live and dead bacteria was calculated and studied by using ImageJ software. The experiments were performed in triplicate. The statistical data were analyzed by pairwise comparisons using the nonparametric Mann-Whitney test with a level of statistical significance of p<0.05. Values are cited and represented as medians. S. aureus 15981 adherence was 942-fold lower on MAPTMS-TMOS coating than on uncoated titanium. According with our results, MAPTMS-TMOS sol-gel coating is a promising antiadherent surface for S. aureus. More studies are necessary in order to evaluate this property with other species and strains

Four uncemented Symax hip stems were extracted at three weeks and nine, 13 and 32 months, respectively, for reasons other than loosening. The reasons for implant removal were infection in two cases, recurrent dislocation in one and acetabular fracture in one. They were analysed to assess the effect and behaviour of an electrochemically deposited, completely resorbable biomimetic BONIT-hydroxyapatite (HA) coating (proximal part) and a DOTIZE surface treatment (distal part) using qualitative histology, quantitative histomorphometry and scanning electron microscopy (SEM). Early and direct bone-implant bonding with signs of active remodelling of bone and the HA coating were demonstrated by histology and SEM. No loose BONIT-HA particles or delamination of the coating were observed, and there was no inflammation or fibrous interposition at the interface. Histomorphometry showed bone-implant contact varying between 26.5% at three weeks and 83.5% at 13 months at the HA-coated implant surface. The bone density in the area of investigation was between 24.6% at three weeks and 41.1% at 32 months. The DOTIZE surface treatment of the distal part of the stem completely prevented tissue and bone apposition in all cases, thereby optimising proximal stress transfer. The overall features of this implant, in terms of geometry and surface texture, suggest a mechanically stable design with a highly active biomimetic coating, resulting in rapid and extensive osseo-integration, exclusively in the metaphyseal part of the stem. Early remodelling of the HA coating does not seem to have a detrimental effect on short-term bone-implant coupling. There were no adverse effects identified from either the BONIT-HA coating or the DOTIZE surface treatment

Development of antibacterial surfaces or coatings to prevent bacterial adhesion and hence colonization of implants and biofilm formation is an attractive option, in order to reduce the tremendous impact of implant-related infections associated with modern surgery. To overcome the lack of in vivo and clinical models, able to evaluate the performance of anti-adhesive coatings, we designed an in vitro experimental setting that allows to quantitatively evaluate the ability of a coating to reduce bacterial adhesion on a given surface; this model may efficiently serve as a surrogate endpoint to validate anti-adhesive medical devices and compounds. Here we report the results the evaluation of the anti-adhesive properties of a patented, fast-resorbable hydrogel coating, (“Defensive Antibacterial Coating”, DAC). Sterile sandblasted titanium discs of approximately 5cm. 2. surface area were used as substrates for bacterial adhesion. The gel was prepared as follows: syringes prefilled with 300 mg of DAC powder (Novagenit Srl) were reconstituted with 5 ml of sterile water to obtain a hydrogel with a DAC concentration of 6%. Two experiments were conducted. In the first, 200 mg of hydrogel were homogenously spread on the surface of titanium disc, with the spreading device provided by the manufacturer. Both coated and uncoated substrates (controls) were overlaid with a standardized inoculum (10. 8. CFU/ml) of a wild methicillin-resistant Staphylococcus aureus strain, previously isolated from a peri-prosthetic joint infection, for 15, 30, 60 and 120 minutes. Afterwards, non-adherent bacteria were removed by rinsing with sterile saline. The remaining adhered cells were seeded on agar plates for CFU count. In the second experiment, the discs were first inoculated with bacterial cells followed by a treatment with the hydrogel and bacterial count as described above. Ten discs were used for each condition and each time interval (total 160 discs). The adhesion density of S. aureus on titanium discs pre-treated with DAC was significantly lower than that observed on untreated controls at each time point. In particular, the average number of adherent bacteria at 15, 30, 60 and 120 minutes of incubation, was respectively reduced by 86.8%, 80.4%, 74.6% and 66.7%, compared to controls (p<0.001). DAC treatment of discs with previously adhered S. aureus reduced bacterial adhesion, at 15, 30, 60 and 120 minutes of incubation, by, respectively, 84.0% (p<0.05), 72.8%, 72.3% and 64.3% (p<0.001), compared to untreated controls. Our results shows that DAC, “Defensive Antibacterial Coating”, has anti-adhesive properties that allow to reduce bacterial adhesion on a sanded titanium surface by more than 80%, even in the presence of remarkably high bacterial loads (10. 8. CFU/ml), of multi-resistant bacteria (MRSA) and even in the case of previous contamination. Providing anti-adhesive properties to a surface with a fast-resorbable coating may be a safe option to protect inorganic and organic surfaces and biomaterials. Those observation could be the pre-requisite for its in vivo application

Bone ingrowth is desired with uncemented hip implants. Infection is clearly undesirable. We have worked on developing a nanofiber coating for implants that would enhance bone formation while inhibiting infection. Few studies have focused on developing an implant surface nanofiber (NF) coating to prevent infection and enhance osseointegration by local drug release. In this study, coaxial doxycycline (Doxy)-doped polycaprolactone/polyvinyl alcohol (PCL/PVA) Nanofibers were directly deposited on the titanium (Ti) implant surface during electrospinning. The interaction of loaded Doxy with both PVA and PCL NFs was characterized by Raman spectroscopy. The bonding strength of Doxy-doped NF coating on Ti implants was confirmed by a stand single-pass scratch test. The improved implant osseointegration by PCL/PVA NF coatings in vivo was confirmed by scanning electron microscopy, histomorphometry and micro computed tomography at 2, 4 and 8 weeks after implantation. The bone contact surface (%) changes of NF coating group (80%) is significantly higher than that of no NF group (< 5%, p<0.05). Finally, we demonstrated that Doxy-doped NF coating effectively inhibited bacterial infection and enhanced osseointegration in an infected (Staphylococcus aureus) tibia implantation rat model. Doxy released from NF coating inhibited bacterial growth up to 8 weeks in vivo. The maximal push-in force of Doxy-NF coating (38 N) is much higher than that of NF coating group (6.5 N) 8 weeks after implantation (p<0.05), which was further confirmed by quantitative histological analysis and micro computed tomography. These findings indicate that coaxial PCL/PVA NF coating doped with Doxy and/or other drugs have great potential in enhancing implant osseointegration and preventing infection

Introduction. Recently, the combination of press-fit acetabular cup with ceramic articulation is a widely used for implanting cementless acetabular components and has been shown to provide good initial stability. However, these methods may lead to elevating stresses, changing in the bearing geometries, and increasing wear due to deformation of the cup and insert. In addition, there is a potential for failure of ceramic inserts when a large ball head was used because it should be assembled with shallow thickness of the acetabular cup. For risk reduction of it, we applied direct metal tooling (DMT) based on 3D printing for porous coating on the cup. Due to its capability of mechanical strength, DMT coated cup could be feasible to provide better stability than conventional coating. Therefore, we constructed laboratory models for deformation test simulating an press-fit situation with large ceramic ball head to evaluate stability of the DMT coated cup compared with conventional coated cup. Materials and Methods. The deformation test was performed according to the test setup described by Z. M. Jin et al. The under reaming of the cavity in a two-point pinching cavity models of polyurethane (PU) foam block (SAWBONES, Pacific Research Laboratories, USA) with a grade 30 were constructed. Titanium plasma spray (TPS) and direct metal tooling (DMT) coated acetabular cups (BENCOX Mirabo and Z Mirabo Cup, Corentec Co. Ltd., KOREA) with a 52 mm size (n=3, respectively) were used for the test. These cups were implanted into the PU foam blocks, and followed by impaction of the inserts (BIOLOX delta, Ceramtec, GE) with a 36/44 size (n=6) into the acetabupar cups as shown in Fig. 1. Roundness and inner diameter of the acetabular cups and inserts were measured using a coordinate measuring machine (BHN 305, Mitutoyo Neuss, GE) in three levels; E2, E3, and E4 (3, 5, and 7 mm below the front face, respectively). Also, these parameters of the acetabular cup were measured in two level; E1 and E5 (5 and 11 mm below the front face) as shown in Fig. 2. Changes in roundness and inner diameter of the cup and insert were measured to evaluate deformation in relation to porous coating on the acetabular cups. Results. Before implantation cups and inserts, roundness and inner diameters were shown good values. When inserts were impacted into the PU foam blocks, there are no significant change in the inner diameters of the cup and insert. However, changes in roundness of the insert which impacted into the DMT coated cup were less deformable than the TPS coated cup's, especially, in E2 level of the inserts (the nearest region of the acetabular rim) as shown in Fig. 3. Conclusions. We demonstrated that deformation of the acetabular cup was affected by the porous coating methods. Although it was limited to few specimens, our results suggested that DMT coated cup would provide more initial stability than TPS coated cup. For figures/tables, please contact authors directly.

Few studies have been reported focusing on developing implant surface nanofiber (NF) coating to prevent infection and enhance osseointegration by local drug release. In this study, coaxial doxycycline (Doxy)-doped polycaprolactone/polyvinyl alcohol (PCL/PVA) NFs were directly deposited on the titanium (Ti) implant surface during electrospinning. The bonding strength of Doxy-doped NF coating on Ti implants was confirmed by a stand single-pass scratch test. The improved implant osseointegration by PCL/PVA NF coatings in vivo was confirmed by scanning electron microscopy, histomorphometry and micro computed tomography at 2, 4 and 8 weeks after implantation. The bone contact surface (%) changes of NF coating group (80%) is significantly higher than that of no NF group (< 5%, p<0.05). Finally, we demonstrated that Doxy-doped NF coating effectively inhibited bacterial infection and enhanced osseointegration in an infected (Staphylococcus aureus) tibia implantation rat model. Doxy released from NF coating inhibited bacterial growth up to 8 weeks in vivo. The maximal push-in force of Doxy-NF coating (38 N) is much higher than that of NF coating group (6.5 N) 8 weeks after implantation (p<0.05), which was further confirmed by quantitative histological analysis and micro computed tomography. These findings indicate that coaxial PCL/PVA NF coating doped with Doxy and/or other drugs have great potential in enhancing implant osseointegration and preventing infection

Introduction. Intraosseous transcutaneous amputation prostheses (ITAP) provide an alternative means of attaching artificial limbs for amputees. Conventional stump-socket devices are associated with soft tissue complications including; pressure sores and tissue necrosis. ITAP resolves these problems by attaching the exo-prosthesis transcutaneously to the skeleton. The aim of this study is to increase the attachment of dermal fibroblasts to titanium alloy in vitro. Fibronectin (Fn) and laminin 332 (Ln) enhance early cell growth and adhesion. We hypothesize that silanized dual coatings of fibronectin and laminin (SiFnLn) will be more durable when compared with adsorbed dual coating (AdFnLn), and will enhance early fibroblast growth and adhesion compared to single coatings. Methods. The kinetics of dual single and dual protein coating attachment onto titanium alloy was quantified on silanized 10mm diameter discs using radiolabelled Fn (125I-Fn) and Ln (125I-Ln). Sixty discs were polished, sterilized and silanized. Coating durability was assessed when soaked in fetal calf serum (FCS) for 0, 1, 24, 48 and 72hrs. Data was compared to un-silanized Ti discs with the same coatings. Five thousand human dermal fibroblasts were seeded on discs (n = 6) of Ti polished alone (Pol), Ti with adsorbed fibronectin (AdFn), Ti with adsorbed laminin (AdLn), Ti adsorbed dual coating (AdFnLn), Ti silanized (Si), Ti silanized with fibronectin (SiFn), Ti silanized with laminin (SiLn), Ti silanized with a dual coating (SiFnLn) for 24hrs. In order to measure cell adhesion fibroblasts were fixed, vinculin stained using mouse vinculin antibody and alexa fluor. Axiovision Image Analysis software was used to measure cell area, vinculin focal adhesion markers per cell and per unit cell area. Data was analysed in SPSS and significance was assumed at the 0.05 level. Results. Silanized dual coatings bonded to Ti alloy in significantly larger quantities compared with adsorbed coatings at all time points (all p values < 0.05). Fibroblasts cultured on dual coatings were significantly larger, produced more vinculin markers per cell, and per unit cell area compared with single coatings. Cells on SiFnLn were larger with more numerous vinculin markers per cell, and per unit cell area compared with AdFnLn (p<0.05). Conclusion. This study has demonstrated that covalently bonding both fibronectin and laminin to Ti alloy provides a durable, dual coating that enhances early fibroblast growth and attachment compared with either protein coating alone in vitro. Our study showed that there is non-competitive binding of laminin on Ti surfaces in the presence of fibronectin. Dual coatings may be applied to the skin-penetrating region of transcutaneous devices to improve the skin seal and this may have positive implications for the development of ITAP

Coatings for endo-osseous implants have been developed based on phospholipids. Such coatings promote the formation of a very thin superficial rim which is highly enriched with calcium phosphates. Two phospholipid-based preparations have been compared with a standard hydroxyapatite coating. Preparation S was based on phosphatidyl-serine; preparation C was based on a mixture of phosphatidyl-serine, phosphatidyl-choline and cholesterol. Titanium cylinders spammed with titanium foam were the metallic substrate for the coatings; they were implanted in the femoral canal of New Zealand White rabbits and retrieved after 4, 8 and 26 weeks. A back scattered electron microscopy analysis followed. Both phospholipid preparations were shown not to have any inhibitory action on bone apposition and growth and did not elicit any adverse fibrous reaction. Pictures of bone in-growth into the cavities of the titanium foam are present. A truly tight apposition between bone and coating was evident only in the comparative group sprayed with hydroxyapatite, but this latter coating was often fragmented and its constituent granules were evident. The phospholipid-based coatings did not show inhibitory action on bone apposition and growth and did not elicit any adverse fibrous reaction

CaSiO3 has been used a potential bioactive material for bone regeneration. A drawback of the CaSiO3 ceramics is that they possess high dissolution rate of Ca ions leading to a high pH value environment [1], which can disadvantage cell growth. Zn can enhance osteoconductivity of CaP ceramics and stimulate bone formation [2]. The aims of this study are:. In situ preparation and optimization of Zn-CaSiO3 ceramics by the evaluating of physical and chemical properties, osteoblast and osteoclast behavior;. Sol-gel coating the optimized hardystonite (HT, Ca2ZnSi2O7) on Ti-6Al-4V. Zn-CaSiO3 ceramics containing zero, ten, 20 and 50-mol% of Zn were sintered at 1260 °C. The dissolution and apatite formation ability were evaluated by soaking in simulated body fluids. Attachment, proliferation and differentiation of human primary bone-derived cells (HBDC) on ceramic disks were evaluated. Human monocytes isolated from buffy coats were differentiated into mature and functional osteoclast (OC) by culturing them for 21 days on ceramic disks. Then, the optimized HT (50%Zn-CaSiO3) coating on Ti-6Al-4V was prepared by sol-gel spinning method. The incorporation of Zn in CaSiO3 resulted in part of new phase formation (HT) formation in Zn-Ca-Si ceramics. When adding 50 mol% of Zn, only pure HT phase existed. The incorporation of Zn in CaSiO3 decreased the dissolution and pure 50 mol% of Zn (HT ceramics) resulted in the lowest dissolution. Zn-CaSiO3 ceramics with different Zn contents supported HBDC attachment. With the increase of Zn contents, HBDC proliferation and differentiation improved. The surface roughness of Sol-gel HT coating is about 0.49 μm. The thickness of coating is about 1 μm. HT coating has a similar dissolution kinetics and stability with hydroxyapatite coating. Zn decreases the dissolution in Zn-Ca-Si ceramics and enhances HBDC proliferation and differentiation. The optimized HT ceramics (50mol% Zn) support OC resorption and can be used for a stable biomedical coating application

Introduction. Micro-arc oxidation (MAO) is an electrochemical method used to treat metal surfaces. It provides nanoporous pits, and thick oxide layers, and incorporates calcium and phosphorus into the coating layer of titanium alloy. This modification on the surface of titanium alloy by MAO coating would improve the ability of cementless stems to osseointegrate. In spite of these structural and chemical advantages, clinical study of total hip arthroplasty (THA) using MAO coated stem has not yet been reported. In this study, we evaluated the clinical and radiographic results associated with cementless grit-blasted tapered-wedge stems that were identical in geometry but differed with regard to surface treatment with or without MAO coating. Materials & Methods. We performed a retrospective review of 141 THAs using MAO coated stem for a minimum of 5 years and compared them to 219 THAs using the same geometry stem without MAO coating. A cementless Bencox femoral component (Corentec, Seoul, Korea) was used in all hips. It is made of titanium alloy with a straight, double wedged, tapered stem with a rectangular cross-section. Surface treatment was performed using grit blasting with a roughness of 5.5ųm that was available either with or without MAO coating. Clinical and radiographic evaluations were performed preoperatively and at 6 weeks, 3 months, 6 months, and 1 year postoperatively, and then annually. Results. In the MAO coating group, the mean Harris hip score improved from 43.7 points preoperatively to 93.9 points postoperatively. The mean WOMAC score and UCLA activity score at the final follow-up was 17 points (range, 6–34 points) and 6.9 points (range, 5–10 points), respectively. Thigh pain at final follow-up was reported in 2 hips (1.4%), but neither of these hips showed signs of implant loosening or limited daily activities. Complications included one squeaking, one iliopsoas tendonitis, and one deep vein thrombosis. Postoperative Harris hip scores, WOMAC scores, UCLA activity scores, and complication rates did not differ between the two groups. In both groups, no femoral or acetabular component showed radiographic evidence of mechanical loosening, and no components had been revised at the final follow-up. Conclusions. Primary THA using a cementless grit-blasted tapered-wedge stem with MAO coating showed encouraging medium-term outcomes. Further prospective controlled study is required to investigate the long-term implant survival, possible complications, and cost-effectiveness of utilizing MAO coating in THA

Honey has been used as a topical antiseptic for at least 5,000 years. SurgiHoney is a CE licensed sterile product, which has been proven to be non-toxic and effective when used topically in the treatment of chronically infected wounds. The key difference from other medical grade honey is the broad spectrum antimicrobial characteristics with activity against Gram +ve, Gram –ve and multi-resistant organisms. Its novel role against the bacterial bioburden and biofilm associated with periprosthetic infections around total knee arthroplasties (TKA's) is therefore considered. SurgiHoney was used as an implant coating immediately prior to wound closure after implantation of salvage endoprosthesis for multiply revised, infected TKA's undergoing staged reconstruction. We report a consecutive series of multi-revised, infected revision TKA's where SurgiHoney was used as an active antimicrobial coating. We discuss its intra-operative application and early clinical outcomes. The use of Surgihoney as a novel anti-microbial is established in the management of complex wound infections. This is the first reported use of SurgiHoney as a deep, implant coating in the salvage of prosthetic joint infection

Previous studies showed that a fast-resorbable antibacterial hydrogel coating (DAC®, Novagenit Srl, Mezzolombardo, TN, Italy) composed of covalently linked hyaluronan and poly-D, L-lactide, is able to reduce early post-surgical infection both after joint replacement and osteosynthesis. Aim of the present report is to investigate medium-term safety and efficacy of the coating in patients undergoing primary and revision cementless total hip replacement (THR). We designed a two-phases study. In both phases, DAC was prepared according to manufacturer's instructions. In brief, the syringe prefilled with 300 mg of sterile DAC powder was mixed, at the time of surgery, with a solution of 5 mL of sterile water and with the tailored antibiotics, at a concentration ranging from 25 mg/mL to 50 mg/mL. The resulting antibacterial hydrogel was then spread on the outer surface of the prosthesis just before implantation. In the first phase, safety was assessed. Forty-six patients (13 primary and 33 revision THR) were treated with DAC between 2013 and 2015 and evaluated at a 2.8 ± 0.7 years follow up (FU). Antibiotics used for DAC reconstruction were Vancomycin in 33 cases, Vancomycin + Meropenem in 10, Vancomycin + Rifampicin, Teicoplanin or Ceftazidime in 1 case, respectively. Patients were evaluated at 3, 6, 12 months and yearly after with a clinical and radiographic FU. No evidence of infection and no failure/loosening of the prosthesis were observed. No adverse events were reported. The second phase was designed to evaluate efficacy of DAC in preventing infection recurrences after a two stage revision for infected THR. Twenty-seven patients, treated with DAC coating, were compared with a control group of 32, treated in the same time period, without the coating. Demographics, host type and and identified bacteria were similar in the two groups (18.6% of MRSA in DAC group vs 18.5% MRSA in no-DAC group). Patients were evaluated clinically and radiographically at 3, 6, 12 months and yearly thereafter. At a minimum 2 years FU (mean 2.7), we observed 1 dislocation in each group and 2 cases of loosening in the no-DAC group. 4 cases (11%) of recurrence of infection in the no-DAC group (1 MRSA and 3 St. Epidermidis) and no infection recurrences in the DAC group. Due to the small cohort of patients this difference is not statistically significant (Fisher's exact test, p=0.18). This is, to our knowledge, the longest observation concerning the safety and efficacy of the DAC antibacterial coating, applied to hip replacement. The results are in line with those previously reported and point out the absence of side effects of the antibacterial coating in this application and the tendency to reduce re-infection in second stage. This finding needs to be confirmed by a larger dataset

Summary Statement. An Implant Disposable Antibacterial Coating (i-DAC®) is described, consisting of a fully resorbable, biocompatible hydrogel, able to release antibacterial and antibiofilm agents. Direct application of the hydrogel on implants prevented infection occurrence in an in vitro model of peri-prosthetic infection. Introduction. Biofilm-related infections are among the main reasons for failure of joint prosthesis with high associated social and economical costs. Bacterial adhesion and subsequent biofilm formation have been shown to develop early after biomaterials implant into the human body, when a “race to the surface” takes place between the host's cells and the colonizing bacteria eventually present at the surgical site. Providing an antibacterial/antibiofilm coating of the implant may then play a strategic role in preventing biofilm related infections. Here we report the results of a series of in vitro and in vivo studies, partially performed under the European 7th Framework Programme (Implant Disposable Antibiotic Coating, IDAC, collaborative research project # 277988), concerning a fully resorbable, biocompatible antibacterial hydrogel coating (DAC®, Novagenit, Italy). The patented hydrogel, a co-polimer comprising of hyaluronic acid and a polylactic acid, has been designed to be mixed with various antibacterial agents and applied directly on the implant at the time of surgery, being fully resorbed within few days. Patients & Methods. The tested hydrogel (DAC®, Novagenit, Italy) is a derivative of a low molecular weight hyaluronan, grafted with poly-D, L-lactic acid and provided in powder form. At the point of care, the powder is hydrated with the antibiotic or antibiofilm solution, thus generating the final compound to be applied onto the implant surface. In vitro studies were conducted using DAC® coating on different biomaterials, including titanium, chrome-cobalt and polyethylene discs. The release of different antibacterial agents, including vancomycin, ciprofloxacin, meropenem, gentamycin, amikacin, tobramycin, clindamycin, doxycyclin, linezolid, NAsalycilate and N-acetylcisteine, adequately mixed with the hydrogel, has been tested by means of gas chromatography and microbiological methods. In vivo studies were then performed on 35 rabbits divided in 7 groups. Animals were implanted with an intramedullary titanium rod in their femur, with a known inoculum of methicillin-resistant Staph. aureus and vancomycin-loaded DAC® at different concentrations (2% and 5%) and compared with controls. Results. Regardless of the tested material, in vitro studies showed the ability of the hydrogel to be loaded and to sustain the release of the following antibacterial/antibiofilm compounds for up to 96 hours: vancomycin, ciprofloxacin, meropenem, gentamycin, amikacin, tobramycin, clindamycin, doxycyclin, linezolid, NAsalycilate, N-acetylcisteine. In vivo studies showed a bacterial load reduction ranging from 94% to 99.9% using vancomycin-loaded DAC®, compared to controls. Discussion/Conclusion. DAC®, a fast-resorbable antibacterial coating, showed the ability to be loaded with various antibacterial compounds and the ability to provide a highly significant reduction of bacterial colonization of implanted biomaterials in an animal model, opening a new pathway to local prevention and treatment of biofilm-/implant-related infections

Infection is among the first reasons for failure of orthopedic implants. Various antibacterial coatings for implanted biomaterials are under study, but only few technologies are currently available in the clinical setting. Previous studies showed the in vitro and in vivo efficacy and safety of a fast resorbable (<96 h) hyaluronic and polylactic acid based hydrogel, loaded with antibiotic or antibiofilm agents (DAC®, Novagenit Srl, Mezzolombardo, TN). Aim of this study is to report the results of the largest clinical trial in trauma and orthopedic patients. In this prospective, controlled, study, a total of 184 patients (86 treated with internal osteosinthesis for closed fractures and 98 undergoing cementless total hip or knee joint prosthesis) were randomly assigned in three European orthopaedic centers to receive antibiotic-loaded DAC coating or to a control group, without coating. Pre- and post-operative assessment of laboratory tests, wound healing (ASEPSIS score), clinical score (SF-12 score) and x-rays were performed at fixed time intervals. Statistical analysis was performed with Fisher exact test or Student's t test. Significance level was set at p<0.05. The study was approved by the local Ethical Committee and all patients provided a written informed consent. On average, wound healing, clinical scores, laboratory tests and radiographic findings did not show any significant difference between the two-groups at a mean 12 months follow-up (min: 6, max: 18 months). Four surgical site infections and two delayed union were observed in the control group compared to none in the treated group. No local or systemic side effects, that could be related to DAC hydrogel coating, were noted and no detectable interference with bone healing or osteointegration could be found. This is the largest study, with the longest follow-up, reporting on clinical results after the use of a fast-resosrbable anti-bacterial hydrogel coating for orthopaedic and trauma implants. Our results show the safety of the tested coating in different indications; although not statistically significant, the data also show a trend towards surgical site infection reduction, as previously demonstrated in the animal models

Aim. Aim of this study is to present the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating. *. , in patients undergoing internal osteosynthesis for closed fractures. Method. In this prospective, multi-centre, randomized, controlled, prospective study, a total of 260 patients were randomly assigned, in five European orthopaedic centres, to receive the antibiotic-loaded DAC coating or to a control group, without coating. Pre- and post-operative assessment of laboratory tests, wound healing, clinical scores and x-rays were performed at fixed time intervals. Results. 253 patients were available at follow-up. On average, wound healing, clinical scores, laboratory tests and radiographic findings did not show any significant difference between the two-groups. Six early surgical site infections (4.6%) were observed in the control group compared to none in the treated group (p < 0.02). No local or systemic side effects related to DAC hydrogel coating were observed and no detectable interference with bone healing was noted. Conclusions. The use of a fast-resorbable, antibiotic-loaded hydrogel implant coating provides a reduced rate of early surgical site infections after internal osteosynthesis for closed fractures, without any detectable adverse event or side effects

Problems. Biofilm infections are increasingly associated with orthopedic implants. Bacteria form biofilms on the surfaces of orthopedic devices. The biofilm is considered to be a common cause of persistent infections at a surgical site. The growth and the maturation of biofilm are enhanced by the flow of broth in culture environment. In order to reduce the incidence of implant-associated infections, we developed a novel coating technology of hydroxyapatite (HA) containing silver (Ag). We previously reported that the Ag-HA coating inhibits biofilm formation under flow condition of Trypto Soy Broth + 0.25% glucose for 7 days. In this study, we evaluated whether the Ag-HA coating continuously inhibits the biofilm formation on its surface under flow condition of fetal bovine serum, which contains many in vivo substrates such as proteins. Materials and Method. The commercial pure titanium disks were used as substrates. Ag-HA or HA powder was sprayed onto the substrates using a flame spraying system. The HA coating disks were used as negative control. The biofilm-forming methicillin resistant Staphylococcus aureus (BF-MRSA; UOEH6) strain was used. The bacterial suspension (about 10. 5. colony forming units) was inoculated into 24-well sterile polystyrene tissue culture plates. The Ag-HA and HA coating disks were aseptically placed in the wells. After cultivation at 37°C for 1 hour, the disks were rinsed twice with 500 μL sterile PBS (−) to eliminate the non-adherent bacteria. After rinsing, the disks were transferred into petri-dish containing heat-inactivated FBS with a stirring bar on the magnetic stirrer and they were cultured at 37 °C for 24 hours, 7 and 14 days. In the meantime, the stirring bar was spun at 60 rounds per minute. Then, the disks were immersed in a fluorescent reagent to stain the biofilm. Finally, the biofilm on each disk was observed by a fluorescence microscope and the biofilm-covered rate (BCR) on the surfaces of them was calculated using the NIH image software. Results. Biofilm was hardly observed on the Ag-HA coating. However, the biofilm on the HA coating was extensive and mature (Fig. 1). At 24h after cultivation, BCRs of BF-MRSA were 2.1% and 19.8% on the Ag-HA and HA coatings, respectively. Similarly, they were 6.3% and 12.4% on the Ag-HA and HA coatings at 7 days. At 14 days they were 20.6% and 39.4% on the Ag-HA and HA coatings, respectively. These results demonstrate that BCRs on the Ag-HA coating were significantly lower than those on the HA coating (Fig. 2). Discussion. The Ag-HA coating continuously showed the inhibiting ability for biofilm formation under flow condition for 14 days. Ag ions inhibited the biofilm formation on the Ag-HA coating by killing adherent bacteria in the vicinity of the surface, although the release rate of Ag ions was high until 24h after immersion and decreased thereafter. The Ag-HA coating would be expected to contribute to reduction of implant-related biofilm infection

Aim. Infection rates after revision THA vary widely, up to 12%. In countries that use antibiotic-loaded cemented stems in combination with perioperative IV antibiotics, infection rates in registry studies are lower. In many countries, however, cementless revision implants are preferred. Our aim was to apply an antibiotic-loaded calcium sulfate coating to cementless revision stems to reduce periprosthetic joint infection (PJI). This study sought to answer two questions: 1) Does the coating of cementless revision stems with calcium sulfate inhibit osteointegration in THA? 2) Does the antibiotic-loaded calcium sulfate coating of revision stems reduce the incidence of PJI?. Method. From Dec. 2010 to Dec. 2015, 111 consecutive revision femoral stems were coated with commercially pure calcium sulfate. 10cc of calcium sulfate was mixed with 1g of vancomycin powder and 240mg of tobramycin liquid and applied to the stem in a semi-firm liquid state immediately prior to stem insertion. The results are compared to a designated control cohort (N=104) performed across the previous 5 years. The surgical methods were comparable, but for the stem coating. All patients were staged preoperatively using the Musculoskeletal Infection Society Staging System and followed for at least 1 year. Results. In the study group of coated stems, there were 46 A hosts, 56 B hosts, and 9 C hosts. In the control group, there were 45 A hosts, 52 B hosts, and 7 C hosts. Both cohorts had 0 cases of aseptic loosening. The overall rate of PJI in the study cohort was 2.7%. Of the 111 revisions, 69 were aseptic (PJI=1.4%) and 42 were second stage revisions for infection (PJI=4.8%). PJI occurred in 2.2% of A hosts, 1.8% of B hosts, and 11.1% of C hosts. In the control cohort, the overall rate of PJI was 7.7%. Of the 104 revisions, 74 were aseptic (PJI=1.4%) and 30 were second stage revisions for infection (PJI=23.3%). PJI occurred in 6.7% of A hosts, 5.8% of B hosts, and 28.6% of C hosts. The results show a reduction in PJI from 7.7% in the control group to 2.7% in the study group and were found to be statistically significant at p-value<0.1 (p=0.09). Conclusions. The application of antibiotic-loaded calcium sulfate to cementless revision femoral stems does reduce PJI. Importantly, this coating did not inhibit osteointegration of the femoral stem. The reduced infection rate in this study supports the concept that bacteria frequently contaminate and reside within the femoral canal

Aims. The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) may improve quality of life for amputees by avoiding soft-tissue complications associated with socket prostheses and by improving sensory feedback and function. It relies on the formation of a seal between the soft tissues and the implant and currently has a flange with drilled holes to promote dermal attachment. Despite this, infection remains a significant risk. This study explored alternative strategies to enhance soft-tissue integration. Materials and Methods. The effect of ITAP pins with a fully porous titanium alloy flange with interconnected pores on soft-tissue integration was investigated. The flanges were coated with fibronectin-functionalised hydroxyapatite and silver coatings, which have been shown to have an antibacterial effect, while also promoting viable fibroblast growth in vitro. The ITAP pins were implanted along the length of ovine tibias, and histological assessment was undertaken four weeks post-operatively. Results. The porous titanium alloy flange reduced epithelial downgrowth and increased soft-tissue integration compared with the current drilled flange. The addition of coatings did not enhance these effects. Conclusion. These results indicate that a fully porous titanium alloy flange has the potential to increase the soft-tissue seal around ITAP and reduce susceptibility to infection compared with the current design. Cite this article: Bone Joint J 2017;99-B:393–400

Beta–tricalciumphosphate(β-TCP)coatinglayerisknown to be resorbed much faster than hydroxyapatite(HA), however, there has been few reports explaining the exact mechanism until now. Therefore, we investigated whether the resorption mechanisms of these two compounds are same, if not, what is the difference. Eighty titanium discs with 12mm in diameter and 2mm in thickness were coated with HA(n=40) or β-TCP(n=40) by dip and spin coating method. In each group, the specimens were divided into 2 subgroups respectively; Dissolution (D, n=20) group and Osteoclast culture (C, n=20) group. The coated discs in D group were immersed in the cell culture media for 5 days, whereas, in C group, osteoclast-like cells (5×103 cells/500μ), which were isolated form human giant cell tumor, were seeded on the specimens and cultured for 5 days. Cultured cells were defined as osteoclast by the determination of osteoclast marker (tartrate-resistant acid phosphatase, TRAP). After immersion or osteoclast culture, the dissolution characteristics of coating surface were observed using light microscope (LM) and scanning electron microscope (SEM). And the area fraction of resorption lacunae formed by osteoclast was analyzed by image analysis to evaluate the activity of osteoclastic degradation. After 5 days of dissolution, there were much more cracks and denuded areas in β-TCP coating compared to HA coating. In C group, the osteoclasts covering the coating layer were identified on LM and SEM images. Mean area fraction of resorption lacunae in HA-C group was 11.62%, which was significantly higher than that of 0.73% of β-TCP-C group (p=0.001). We conclude that the resorption mechanism of HA and β-TCP coating layers was different each other in vitro study. The coated β-TCP was degraded mainly by dissolution and also tended to be separated from implant, on the other hand, the HA coating layer was resorbed by osteoclastic activity

Aims. Biofilm formation is intrinsic to prosthetic joint infection (PJI). In the current study, we evaluated the effects of silver-containing hydroxyapatite (Ag-HA) coating and vancomycin (VCM) on methicillin-resistant Staphylococcus aureus (MRSA) biofilm formation. Methods. Pure titanium discs (Ti discs), Ti discs coated with HA (HA discs), and 3% Ag-HA discs developed using a thermal spraying were inoculated with MRSA suspensions containing a mean in vitro 4.3 (SD 0.8) x 10. 6. or 43.0 (SD 8.4) x 10. 5. colony-forming units (CFUs). Immediately after MRSA inoculation, sterile phosphate-buffered saline or VCM (20 µg/ml) was added, and the discs were incubated for 24 hours at 37°C. Viable cell counting, 3D confocal laser scanning microscopy with Airyscan, and scanning electron microscopy were then performed. HA discs and Ag HA discs were implanted subcutaneously in vivo in the dorsum of rats, and MRSA suspensions containing a mean in vivo 7.2 (SD 0.4) x 10. 6.   or 72.0 (SD 4.2) x 10. 5.   CFUs were inoculated on the discs. VCM was injected subcutaneously daily every 12 hours followed by viable cell counting. Results. Biofilms that formed on HA discs were thicker and larger than those on Ti discs, whereas those on Ag-HA discs were thinner and smaller than those on Ti discs. Viable bacterial counts in vivo revealed that Ag-HA combined with VCM was the most effective treatment. Conclusion. Ag-HA with VCM has a potential synergistic effect in reducing MRSA biofilm formation and can thus be useful for preventing and treating PJI. Cite this article:Bone Joint Res. 2020;9(5):211–218

We inserted two hydroxyapatite (HA)-coated implants with crystallinities of either 50% (HA-50%) or 75% (HA-75%) bilaterally into the medial femoral condyles of the knees of 16 dogs. The implants were allocated to two groups with implantation periods of 16 and 32 weeks. They were weight-bearing and subjected to controlled micromovement of 250 μm during each gait cycle. After 16 weeks, mechanical fixation of the HA-50% implants was increased threefold as compared with the HA-75% implants. After 32 weeks there was no difference between HA-50% and HA-75%. Fixation of HA-75% increased from 16 to 32 weeks whereas that of HA-50% was unchanged. HA-50% implants had 100% more bone ingrowth than HA-75% implants after 16 weeks. More HA coating was removed on HA-50% implants compared with HA-75% implants after both 16 and 32 weeks. No further loss of the HA coating was shown from 16 to 32 weeks. Our study suggests that the crystallinity of the HA coating is an important factor in its bioactivity and resorption during weight-bearing conditions. Our findings suggest two phases of coating resorption, an initial rapid loss, followed by a slow loss. Resorbed HA coating was partly replaced by bone ingrowth, suggesting that implant fixation will be durable

The aim of this study was to evaluate whether coating titanium discs with selenium in the form of sodium selenite decreased bacterial adhesion of Staphylococcus aureus and Staph. epidermidis and impeded osteoblastic cell growth. In order to evaluate bacterial adhesion, sterile titanium discs were coated with increasing concentrations of selenium and incubated with bacterial solutions of Staph. aureus (ATCC 29213) and Staph. epidermidis (DSM 3269) and stained with Safranin-O. The effect of selenium on osteoblastic cell growth was also observed. The adherence of MG-63 cells on the coated discs was detected by staining with Safranin-O. The proportion of covered area was calculated with imaging software. The tested Staph. aureus strain showed a significantly reduced attachment on titanium discs with 0.5% (p = 0.011) and 0.2% (p = 0.02) selenium coating. Our test strain from Staph. epidermidis showed a highly significant reduction in bacterial adherence on discs coated with 0.5% (p = 0.0099) and 0.2% (p = 0.002) selenium solution. There was no inhibitory effect of the selenium coating on the osteoblastic cell growth. Selenium coating is a promising method to reduce bacterial attachment on prosthetic material. Cite this article: Bone Joint J 2013;95-B:678–82

Gentamicin was described with negative effects on bone formation. Arginin-Glycin-Aspartat (RGD) sequences play a key role in the adhesion of osteoblasts and have proven to improve implant integration. We have already shown a significant reduction in infection rates by a combined gentamicin-hydroxyapatite (HA) and gentamicin-RGD-hydroxyapatite coating in a rabbit infection model for cementless joint prostheses. The purpose of the study was to assess whether the gentamicin-HA coating had a negative effect on the implant integration and new bone formation, compared to pure HA coating, and whether this could be enhanced by additional gentamicin-RGD-HA coating. There were 5 study groups (8 animals per group) with 5 different stainless steel K-wires: uncoated, HA coated, gentamicin-HA, RGD-coated, gentamicin-RGD-HA coated. A 2.0 mm K-wire with one type of coating was introduced into the intramedullary canal of the tibia. The tibiae were harvested after 12 weeks and standardised longitudinal and transverse sections were performed to study new bone formation around the implant and implant bone contact. New bone formation and osseointegration of the implant surface was assessed using histomorphometrical methods by computerised semi-quantitative analysis and histological methods. There were no significant differences between the HA and the gentamicin-HA group although new bone formation and implant bone contact were always higher for the pure HA coating. Additional RGD coating on the gentamicin-RGD-HA coating did not show significant improvement of bone formation and implant integration compared to gentamicin-HA. There was a very similar histological appearance of new bone formation between all groups with very low frequency of giant cells, indicating good biocompatibility. Gentamicin-HA coating did not have significant negative effects on bone formation and bone implant contact, compared to pure HA coating. In combination with the excellent ability to reduce infection rates, gentamicin-HA coating may have a high interest in cement-less arthroplasty

Introduction. Pin-tract infections are a common problem in orthopaedic surgery, which limits the time an external fixator or Taylor spatial frame can be applied to a patient. The purpose of our study is to evaluate the ability of a novel implant surface coating — cationic steroid antibiotic (CSA)-44 — to delay or prevent the onset of these infections. This coating mimics endogenous antimicrobial peptides of the innate immune system and has been shown to effectively eradicate biofilms as well as prevent infection and stimulate healing of open, contaminated fractures. Methods. Surgeries were performed on 20 animals (outbred; Sprague-Dawley strain rats). Each animal received both CSA-coated and standard-of-care titanium pins, with pins randomized to the fifth or sixth vertebrae prior to surgeries. Animals were also randomized to either “Imaging” (imaging analysis) or “Infection” (microbiological analysis) cohorts. Surgeons were blinded to pin types and analyses cohorts. Digital images of pin sites were collected weekly over 12 weeks, and then graded by two orthopaedic surgery residents according to an established Likert scale. Graders were blinded to animal numbers, pin types, and timepoints (Figure 1). For the infection analysis cohort, four specimens per site were subjected to microbiological analysis from each site (i.e. pin, superficial skin swab, deep skin swab, sonicated bone). Each specimen was processed on three different microbiological plates (i.e. BAP, CAN, MAC) using standardized techniques. Imaging analysis was performed by dissecting vertebrae en bloc with pin retained, followed by fixation in 10% neutral buffered formalin for 72 hours. Following a graded ethanol series and storage in 70% ethanol, specimens were scanned with microcomputed tomography (µCT). Statistical analyses were performed to compare pin site appearance (chi-square testing) as well as total bacterial colony counts within each plate cohort and imaging data (Kruskal-Wallis testing); for all tests, significance was set at α=0.05. Results. Weekly digital images of each pin site were collected, graded, and then averaged (Figure 2). Statistical analysis showed no significant difference in pin appearance between the control and CSA pin cohorts at any timepoints. For the infection analysis cohort, bacterial colonies were counted on BAP, CAN, and MAC plates, followed by bacteria species identification (Figure3). Statistical analysis showed no significant difference in total bacterial colony counts between the control and CSA pin cohorts in any of the plate groups. For the imaging cohort, post-processing and subsequent data and statistical analyses are ongoing. Discussion. No significant differences were found between the control and CSA pin cohorts, with respect to pin appearance during the 12-week study or total bacterial colony counts on three plates, indicating that the control and CSA pins performed equivalently. Imaging analysis is ongoing. Although the environmentally-acquired infection model in an outbred rat strain was used to replicate the onset of pin tract infections in human populations, many animals showed Grade 1 or 2 pin site appearances at the 12-week endpoint. A follow-on study is underway using a direct bacterial seeding model. For any figures or tables, please contact the authors directly

Aim. Infection remains among the first reasons of failure of joint prosthesis. According to various preclinical reports, antibacterial coatings of implants may prevent bacterial adhesion and biofilm formation. Aim of this study is to present the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating. *. , in patients undergoing hip or knee prosthesis. Method. In this multi-center, randomized, prospective, study, a total of 380 patients, scheduled to undergo primary or revision total hip or knee joint replacement, using a cementless or a hybrid implant, were randomly assigned, in six European orthopedic centers, to receive the antibiotic-loaded DAC coating or to a control group, without coating. Pre- and post-operative assessment of clinical scores, wound healing, laboratory tests and x-ray were performed at fixed time intervals. Results. Overall 373 patients were available at a minimum follow-up of 6 months (maximum 24 months). On average, wound healing, laboratory tests and radiographic findings did not show any significant difference between the two-groups. Eleven early surgical site infections (6%) were observed in the control group, compared to one (0.6%) in the treated group (p=0.003). No local or systemic side effects related to DAC hydrogel coating were observed and no detectable interference with implant osteointegration was noted. Conclusions. The use of a fast-resorbable, antibiotic-loaded hydrogel implant coating provides a reduced rate of early surgical site infections after hip or knee joint replacement using cementless or hybrid implants, without any detectable adverse event or side effects

Introduction. Following amputation, residual stumps used to attach the external prostheses can be associated with sores, infection and skin necrosis. These problems could be overcome by off loading the soft tissues. Intraosseous transcutaneous amputation prostheses (ITAP) attach external implants directly to residual bone reducing these complications. However, a tight seal at the skin implant interface is crucial in preventing epithelial down-growth and infection. Fibronectin (Fn) and laminin 332 (Ln), enhance early cell growth and adhesion of keratinocytes. Silanization to titanium alloy (Ti) allows these proteins to bond to the metal directly. We hypothesize that silanized dual coatings of fibronectin and laminin (SiFnLn) will be more durable than absorbed proteins and that keratinocyte adhesion will be increased compared with Ti controls and single silanized proteins. Methods. 10 mm diameter Ti alloy discs were polished, sterilized and silanized. The kinetics of silanized single and dual protein coating attachment onto titanium alloy was quantified using radio-labelled Fn(125I-Fn) and Ln(125I-Ln). Coating durability was assessed when soaked in fetal calf serum (FCS) for 0, 1, 24, 48, 72hrs. Data was compared to un-silanized Ti discs with the same amount of adsorbed proteins. In order to study cell attachment 20 × 103 keratinocytes were seeded on the discs (n = 6): silanized (Si), silanized fibronectin (SiFn), silanized laminin (SiLn), silanized dual coating (SiFnLn) for 1, 4 and 24hrs. Adhesion of cells was assessed using mouse vinculin antibody for 2hrs and alexafluor for 1hr which stains focal adhesions responsible for attaching cells to surfaces. Axiovision Image Analysis software was used to measure cell area, vinculin markers per cell unit and per unit cell area on 15 cells per disc. Data was analysed in SPSS and significance was assumed at the 0.05 level. Results. Silanized dual coatings bonded to Ti alloy in significantly larger quantities compared with adsorbed coatings (all p values < 0.05). When proteins were combined on silanized discs the same amount of each protein was attached as when used as a single coating (i.e. non competitive binding). Keratinocytes cultured on silanized dual coatings were significantly larger, produced more vinculin markers per unit cell and per cell area compared with single coatings at all time points. Conclusion. This study has demonstrated that silanized using dual proteins on Ti alloy enhances early keratinocyte growth and attachment in vitro. It also shows that there is non-competitive binding of laminin to Ti alloys in presence of fibronectin. This may lead to improved epidermal attachment to ITAP creating a tight seal at the implant interface, which will prevent migration of the epithelium and subsequent infection in vivo

Introduction. Inspired by mussel-adhesion phenomena in nature can integrate inorganic hydroxyapatite crystals within versatile materials. This is a simple, aqueous, two-step functionalization approach, called polydopamine-assisted hydroxyapatite formation (pHAF), that consists of i) the chemical activation of material surfaces via polydopamine coating and ii) the growth of hydroxyapatite in a simulated body fluid (SBF). We presumed polydopamine coating on the surface of titanium alloy would improve the ability of cementless stems to osseointegrate. We therefore compared the in vitro ability of cells to adhere to polydopamine coated Ti alloy and machined Ti alloy. Method. We performed energy-dispersive x-ray spectroscopy and scanned electron microscopy investigations to assess the structure and morphology of the surfaces. Biologic and morphologic responses to osteoblast cell lines (MC3T-E1) were then examined by measuring cell proliferation, cell differentiation (alkaline phosphatase activity), and avb3 integrin. Results. Cell proliferation, alkaline phosphatase activity, migration, and adhesion were not increased in the polydopamine coated Ti alloy compared to other group. And, the polydopamine coated Ti alloy shows better apatite forming ability than the untreated one, as evidenced by apatite formation after SBF immersion for 14 days. Discussion. The surface modifications we used (polydopamine coating) enhanced the apatite formation, but did not change the biocompatibility (proliferation and migration of osteoblastlike cells) of Ti alloy

INTRODUCTION. Electron beam melting is a promising technique to produce surface structures for cementless implants. Biomimetic apatite coatings can be used to enhance bone ingrowth. The goal of this study was to evaluate bone ingrowth of an E-beam produced structure with biomimetic coating and compare this to an uncoated structure and a conventionally made implant surface. METHODS. Implants. The implants (10×4×4mm) were produced with E-beam technology. (Eurocoating). All E-beam implants had a cubic surface structure (porosity 77%). Two structures were coated (Eurocoating), one with hydroxyapatite (cubicHA) and one with brushite (cubicBR). One was left uncoated. A control specimen with a titanium plasma spray coating (TiPS) was also tested. (Figure 1). Experimental design. Surgery was performed on 12 goats. A double set of specimens was implanted in the iliac crest. 4 goats were sacrificed 3 weeks after surgery and 8 goats after 15 weeks. Push out test. The specimens were pushed out the surrounding bone by a Material Testing System (MTS) to define the mechanical strength of the bone-implant interface. Histology. Maximum bone ingrowth depth was measured with fluorescence microscopy (5 and 10 weeks) and light microscopy at HE stained slices (15 weeks). RESULTS. The mechanical strength of the bone-implant interface of the cubic structure and the cubicHA were significantly higher compared to the TiPS control at 15 weeks of implantation. (Figure 2). The maximum bone ingrowth depth of the cubicHA and cubicBR was significantly greater compared to the uncoated cubic structure at respectively 5 & 15 and 5, 10 & 15 weeks. (Figure 3). DISCUSSION & CONCLUSIONS. The results of this study are promising. The E-beam structure performed better than a clinically successful coating. Application of a biomimetic CaP based coating on this E-beam surface provided enhanced bone ingrowth. A large surface area associated with a high porosity (as seen in the cubic structure) is known to allow better bone ingrowth. However a setback of a high porosity is that it takes more time before full integration is established. Application of a biomimetic coating appeared to overcome this by providing improved fixation by bone ingrowth in the early postoperative period. ACKNOWLEDGEMENTS. This study is cosponsored by Provincia Autonoma di Trento and Eurocoating SpA, Trento, Italy

The use of antibiotic-loaded cement has become a well-accepted method to develop high local antibiotic concentrations in orthopedic surgery. A new surgical technique has been established in our department in order to further increase the local antibiotic concentration, when implanting a prosthesis during revision surgery. By additional superficial vancomycin coating of the bone cement, high local antibiotic concentrations are generated. They should reach inhibiting and bactericidal concentrations of the respective pathogen during the first days after surgery. The aim of this study was to state the safety of this method by analyzing postoperative serum and drain vancomycin concentrations. Attention was focused on possible systemic side effects. To determine nephrotoxicity, creatinine levels were also measured. In total 32 revision operations (hip n=10, knee n=22) with additional superficial vancomycin coating were performed between 05/2013 and 04/2015. Procedures with removal of the prosthesis following temporary spacer implantation were excluded. In nine cases a one-stage procedure was performed, while in the others an arthroplasty or arthrodesis was performed after temporary spacer explantation. Vancomycin powder (2 grams) was added superficially to the surface of the bone cement and pressed onto manually before curing. Postoperative Vancomycin levels were measured in serum and the drain on day 1 to 5 or until the drain has been removed. In total 90 blood serum samples and 100 drain fluid samples were obtained. The highest median vancomycin level from the drain was documented on postoperative day 1 with a value of 555.3 μg/mL (range 66.1 – 1081.8), continually decreasing until postoperative day 4. The highest value was documented on the second postoperative day with 2170.0 μg/mL. On the first postoperative day, a median serum vancomycin level of 3.35 μg/mL was present (range <2.0 – 8.5), while from postoperative day 2 to 5 a median level less than 2.0 μg/mL (range <2.0 – 7.2) was documented. Anaphylactic reaction, red man syndrome or fever and chills were not observed after the surgical procedure. Furthermore, no subjective hearing loss was reported. Only in one case, a creatinine increase of 0.5 mg/dL from baseline value was detected. In this case the patient suffered preoperatively from a chronic kidney insufficiency. In total two reinfections occurred, one after explanting a spacer with subsequent hip total endoprosthesis, the other one after a one-stage hip revision. Superficial Vancomycin Coating of bone cement in orthopedic revision surgery represents a safe method to increase local inhibiting vancomycin concentrations

This study evaluated the biologic fixation of two different titanium porous coatings: a clinically successful sintered spherical bead coating [. 1. ] and a new sintered asymmetric particle coating (STIKTITE™, Smith & Nephew). The spherical bead coating has a porosity of about 50% and an average pore size of about 220 μm, whereas the STIKTITE coating has greater porosity (about 62%) and slightly smaller average pore size (about 200 μm). Biologic fixation was assessed using a load-bearing ovine model in which coated semi-circular disc implants were inserted into a defect created in the cancellous bone parallel to and approximately 3 mm below the medial tibial plateau [. 2. ] similar to the method reported by Ignatius [. 3. ]. The implants were slightly thicker than the defect created, producing a 0.2-mm overall pressfit. Initial implant stability was assessed using mechanical push-out (n = 3) immediately after implantation into cadaveric ovine bone. Quantitative mechanical push-out testing and qualitative histology (n = 9 and n = 2, respectively, per group per time point) was performed after six and 26 weeks in vivo. The time-zero average peak push-out load (±S.D.) of the STIKTITE group (95±3 N) was found to be significantly greater (p < 0.02) than that of the spherical bead group (36±5 N). By six weeks in vivo, the average peak push-out load for the STIKTITE group was up to 1001±362 N, and that for the spherical bead group was up to 985±425 N, both representing a significant increase compared to their time-zero results (p < 0.0005). From six to twenty-six weeks in vivo, there was again a significant increase in the peak push-out load irrespective of group (p < 0.0005), with the average peak push-out loads up to 1620±406 N and 1444±446 N for the STIK-TITE and spherical bead groups, respectively. Histology revealed bone ingrowth in both groups that confirmed the findings of the mechanical push-out testing. While the STIKTITE group showed a trend toward greater biologic fixation, overall there was insufficient evidence to support differences between the two groups (p = 0.47) irrespective of the amount of time in vivo. The results of this study confirm the ability of the STIK-TITE coating to achieve superior initial stability. This improved initial stability reduces the reliance on adjunct fixation (such as screws) or large amounts of press-fit to prevent micromotion and create an environment suitable for long-term bone ingrowth. The results also suggest that the STIKTITE coating had a tendency to initiate and maintain bone ingrowth under load-bearing conditions to a level greater than that of a clinically successful sintered bead coating. Because loading of the implant can cause micromotion at the bone/implant interface, models like the one used in this study likely provide a more challenging and realistic representation of anticipated clinical conditions than models with minimal implant loading

Introduction: One of the main factors in the success of impaction bone grafting (IBG) in revision hip surgery is its ability to resist shear and to form a stable construct. Bone marrow contains multipotent skeletal stem cells and we propose that in combination with allograft will produce a living composite with biological and mechanical potential. In this study we looked at whether coating of the allograft with type 1 collagen followed by seeding with human bone marrow stromal cells (hBMSC) would enhance the grafts mechanical and biological properties. Methods: A control group of plain allograft and three experimental groups where used to determine the effects that collagen and hBMSC have on IBG. The samples where impacted in standardised fashion previously validated to replicate femoral IBG, and cultured in vitro for 2 weeks. The samples then underwent mechanical shear testing and biochemical analysis for DNA content and Osteogenic activity. Results: Collagen coating of the allograft prior to seeding with hBMSC significantly enhanced the mechanical properties of the construct compared to the ‘gold standard’ of plain allograft with a 22% increase in shear strength (p=0.002). The collagen coated group also showed increased osteogenic differentiation of the stromal cells (Alkaline Phospatase specific activity: 124 +/− 18.6 vs 54.6 +/− 9.6 nM pNPP/Hr/ngDNA p= < 0.01). Discussion: This study has shown a role in the improvement of the biomechanical properties of IBG by coating with collagen and seeding with hBMSC. Collagen coating of IBG is a simple process and translation of the technique into the theatre setting feasible. The improvement in shear strength and cohesion could lead to earlier weight bearing for the patients and allow quicker recovery. The therapeutic implications of such composites auger well for orthopaedic applications. We are currently strengthening the above findings with an in vivo study

The rationale for a degradable bioactive glass coating is to lead the bone to appose gradually to the metal without the release of non-degradable particles. Two formulations of bioactive glasses, already described in the literature, have been studied: bg A and bg F. A non-bioactive glass (glass H) was sprayed as a control. Glass-coated Ti6Al4V cylinders were implanted in the femoral canal of New Zealand White rabbits. Samples were analysed by back scattered electron microscopy (BSEM) and electron dispersive analysis (EDX). Bone was in tight apposition with the coating. As time progressed, images were found where bone showed features of physiological remodelling (newly formed bone filling areas of bone resorption) close to the coating. At the interface the apposition was so tight that it was not possible to discern a clear demarcation, even at higher magnification (more than 2500x). There was a gradual degradation during time and at 10 months bone was found apposed directly to the metal in more than half of the samples. In contrast, the non-bioactive glass coating showed complete integrity at any time examined and a clear demarcation with the coating was evident. Two peculiar features of the behaviour of bioactive glass coatings in vivo are: (a) degradation during time; and (b) promotion of a tight apposition with the newly formed bone

We report the radiological and clinical outcome of a press-fit (SLF) acetabular component at two to three years in two groups of patients having primary total hip replacement. In 69 the implant was coated with hydroxyapatite (HA) and in 40 it was uncoated. The stability of the cup was assessed by measurement of proximal migration and change in the angle of inclination. The clinical results in the two groups did not differ significantly, and the mean proximal linear wear was similar in both. Fewer radiolucent lines (RLLs) were seen on the radiographs of cups coated with HA. The mean proximal migration was studied by calculating regression lines for each patient using migration measurements: for the SLF+HA group the mean slope was 0.06 mm/year and for the SLF–HA group 0.20 mm/year (p = 0.22). The change in the angle of inclination during follow-up was also consistently smaller in HA–coated cups. Using regression methods the SLF+HA group had a mean slope of 0.08°/year and the SLF-HA group 0.44°/year (p = 0.023). Partial HA coating appeared to have no effect on the clinical outcome or on the rate of wear of polyethylene, but there was a trend towards a reduced rate of proximal migration, and a significant reduction in rotational migration and the number of radiolucent lines. This suggests that HA coating enhances the stability of this acetabular component

This study investigates the survival (with gross radiological loosening) rates of prostheses following uncemented Total Shoulder Arthroplasties (TSAs) focusing on the glenoid baseplate fixation. All uncemented TSAs inserted in one shoulder unit from 1989 to 2001 were entered onto a database prospectively and the patients monitored to death or failure of the implant, resulting in revision surgery. Over 80% of the surviving implants were monitored on sequential radiographs and the radiological loosening rate was observed. 273 TSAs have been monitored – 193 with a porous coated glenoid baseplate and 80 with a hydroxyapatite coating on top of the porous coating. The Survival rates (%) of the non-HA coated base-plates at 1 to 12 years using the Life Table Method were:- 97, 93, 89, 83, 83, 81, 79, 79, 77, 75, 75 & 75% respectively. The Survival rates for the HA coated glenoid baseplates at 1 to 4 years were 100, 97, 93, & 93% respectively. Failures were predominantly due to mechanical loosening and glenoid disassembly with only 3 cases of infection documented. Thus by 4 years there was a statistically significant improvement in survival of the glenoids. Survival rates were further reduced when radiological loosening was taken into account. The earlier series was analysed to assess the survival of prostheses inserted for RA and OA. The survival rates at 5 & 10 years were 78% & 70% for OA and 96% & 88% for RA. This Life Table analysis confirms the early benefit from the use of hydroxyapatite coating of the glenoid implant of a TSA. Further improvements, particularly in relation to reducing further the small risk of disassembly are underway

Biocompatibility of Co-Cr alloy was significantly improved by forming rough TiO2 layer on the surface. The TiO2 layer was formed by coating the Co-Cr alloy with Ti through electron beam deposition followed by micro-arc oxidation (MAO) of the Ti. Biocompatibility of Co-Cr alloy was enhanced by coating with titanium, and it was improved further by micro-arc oxidation treatment. MAO process was dependent on the thickness of coated titanium layer and applied voltage. There were close relationships between the phase, morphology and thickness of TiO2 layer and the applied voltage. Biocompatibility of the specimens coated with Ti and MAO treated after Ti coating were evaluated by in vitro ALP activity tests

Aims: Hydroxylapatite (HA) coating is able to enhance bone ingrowth and to reduce early migration of hip prostheses. The optimum coating quality and surface texture is still a matter of debate. Moreover, the signiþ-cance of coating resorption is controversial. In this study the degradation of the coatings HA was evaluated and comparate by SEM. Materials and methods: Four cups with HA coating over a porous-coated surface was iden-tiþed with premature loosening at 2–3 years post-operatively. The HA coating has a thickness of up to 50 μ. The cup was stored in formalin before the SEM analysis. The cup specimens was soaked in 6% sodium hypochlorite to render them anorganic, dehydrated, sputter Ð coated with gold-palladium. Secondary electron images of all specimens were obtained by þeld-emission SEM (Zeiss: DSM.962). Results: Ultrastructural analysis showed that all porous-coated HA coated cups had bridges of bone in direct contact with the implant surface (30% bone on-growth). Different types of coating degradation were observed. Delamination between the coating and implant surface; release of numerous particles or fragments ranging from a few to several dozens of microns. Under high magniþcation resorption of the amorphous phase is shown to be exposing the crystalline phase of the coating grains so that the grain boundaries become fragile and easily to be phagocytosed by osteoclasts. Conclusions: This study suggested that resorption disintegrates the HA Ð coating and reduces the bonding strength between implant and bone and the strength of the coatingÐimplant interface, which might lead to implant loosening, coating delamination and acceleration of third body wear processes

In a single-blind, randomised series of knee replacements in 116 patients, we used radiostereometric analysis (RSA) to measure micromotion in three types of tibial implant fixation for two years after knee replacement. We compared hydroxyapatite-augmented porous coating, porous coating, and cemented fixation of the same design of tibial component. At one to two years, porous-coated implants migrated at a statistically significantly higher rate than hydroxyapatite-augmented or cemented implants. There was no significant difference between hydroxyapatite-coated and cemented implants. We conclude that hydroxyapatite augmentation may offer a clinically relevant advantage over a simple porous coating for tibial component fixation, but is no better than cemented fixation

The effect of an advanced porous surface morphology on the mechanical performance of an uncemented femoral knee prosthesis was investigated. Eighteen implants were inserted and then pushed-off from nine paired femurs (Left legs: advanced surface coating; right legs: Porocoat® surface coating as baseline). Bone mineral density (BMD) and anteroposterior dimension were measured, which both were not significantly different between groups. The insertion force was not significantly different, but push-off force was significantly higher in the advanced surface coating group (P = 0.007). BMD had direct relationship with the insertion force and push-off force (p < 0.001). The effect of surface morphology on implant alignment was very small. We suggest that the surface properties create a higher frictional resistance thereby providing a better inherent stability of implants featuring the advanced surface coating

For successful long-term result of non-cemented total hip arthroplasty (THA), direct biological bond between bone and implant through bony ingrowth into the implant is essential. To facilitate strong bond between bone and implant, hydroxyapatite (HA) or hydroxyapatite and tricalcium phosphate (HA-TCP) coated implants have been developed. Early clinical results of HA coated implants were reported very satisfactorily. However, the long-term effects of HA or HA-TCP coating on implants were still controversial. We evaluated the effect of hydroxyapatite and tricalcium phosphate (HA-TCP) coating on fibermetal coated femoral stem. 37 cases using fibermetal coated femoral stem with additional HA-TCP coating and 38 cases using fibermetal coated femoral stem without additional HA-TCP coating were included with average follow-up for 127 months. The mean Harris hip score at final follow-up 91.2 in HA-TCP group and 90.5 in porous group. Engh’s score at final follow-up was 19.1 in HA-TCP group and 18.7 in porous group. Six acetabular components (8.0%, 3 cases in each group) were revised for excessive PE liner wear and liner dissociation from locking mechanism. One femoral stem without HA-TCP coating was considered as a loosening and failure. None of the remaining femoral components (98.7%) showed any signs of aseptic loosening. No significant differences between two groups were found in all parameters. A cement-less porous coated femoral stem provided good clinical function and survival in the medium term regardless of additional HA-TCP coating

This study was conducted to evaluate the clinical and radiographic results on titanium stems that were similar in design but differed with regard to proximal grit-blasted surface texture with and without a hydroxy-apatite (HA) coating. We evaluated 40 patients who had undergone primary total hip replacement by a postero-lateral approach. The stems, all made of titanium alloy, tapered, grit-blasted, collarless, with anterior-posterior fins, did present some differences: in a group of 20 stems a proximal hydroxyapatite coating (thickness: 50 μm) was implanted; in another group of 20 stems the proximal surface was without HA coating. Clinical and radiographic evaluations were performed pre-operatively at 3, 6 and 12 mounths during the first year; than once for the following years.The mean duration of follow-up was 6 years. At the final follow-up examination the Harris hip scores in the HA-coated group (mean, 96 points) and non-HA coated group (mean, 94 points) were similar. Bone-remodelling patterns were similar in the groups and the fast bone integration of the HA coated group. In both groups only two cases of aseptic loosening of the stems were found. After 6 years of follow-up, the clinical and radiographic results among grit-blasted titanium tapered stems with or without Ha coating were perfectly similar. The optimum final bone integration was due just to the singular shape of femur (type B Dorr’s) with an excellent proximal bone stock. The micromotion of implants reduced the bony-anchored stems in two cases

Introduction: Since the establishment of osteosynthesis as the treatment of choice for bone fractures, the issues relating to complications and their prophylaxis have become a major topic of scientific discussion and research in the field of traumatology. Infection of the bone and soft tissue represents one major complication that arises after the implantation of osteosynthetic material at the fracture site. The treatment of these infections is often time-consuming and involves repeated, extensive surgical interventions. The aim of this study was to acquire information about the effect of an antibacterial and biodegradable poly-L-lactide (PLLA) coated titanium plate osteosynthesis on local infection resistance. Material and Methods: We compared infection rates in white New Zealand rabbits after titanium plate osteosynthesis of the tibia with or without antibacterial coating after local percutaneous bacterial inoculations at different concentrations (2x10. 5. –2xlO. 8. ):. group I (n=12):uncoated titanium plate,. group II (n=12): PLLA coated titanium plate,. group III (n=12): titanium plate coated with PLLA + 3% Rifampicin and 7% Fusidic acid, group IV (n= 12): titanium plate coated with PLLA + 2% Octenidin und 8% Irgasan. The plate, the contaminated soft tissues and the underlying bone were removed under sterile conditions after 28 days and quantitatively evaluated for bacterial growth. A stepwise experimental design with an “up-and-down” dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher exact test (p< 0.05). Results: The overall infection rate was 50%. For group I and II the infection rate was both 83% (10 of 12 animals). In group III and IV with antibacterial coating the infection rate was both 17% (2 of 12 animals). The ID50 in the antibacterial coated groups III and IV was recorded as lxl10. 8. CFU, whereas the ID50 values in the groups I and II without antibacterial coating were a hundred times lower at lxl10. 6. CFU, respectively. The difference between the groups with and without antibacterial coating was statistically significant (p=0.033). Conclusions: Using an antibacterial biodegradable PLLA coating on titanium plates, a significant reduction of infection rate in a canine infection model could be demonstrated. For the first time we were able to show, under standardized and reproducable conditions, that an antiseptic coating leads to the same reduction in infection rate as an antibiotic coating. Taking the problem of antibiotic-induced bacterial resistance into consideration, we thus regard the antiseptic coating, which shows the same level of effectiveness, as advantageous

Infection remains among the first reasons for failure of joint prosthesis. Currently, the golden standard for treating prosthetic joint infections (PJIs) is two-stage revision. However, two-stage procedures have been reported to be associated with higher costs and possible higher morbidity and mortality, compared to one-stage. Furthermore, recent studies showed the ability of a fast-resorbable, antibacterial-loaded hydrogel coating to reduce surgical site infections after joint replacement, by preventing bacterial colonization of implants. Aim of this study was then to compare the infection recurrence rate after a one-stage, cemenless exchange, performed with an antibacterial coated implant versus a standardized two-stage revision procedure. In this two-center prospective study, 22 patients, candidate to revision surgery for PJI, were enrolled to undergo a one-stage revision surgery with cementless implants, coated intra-operatively with a fast-resorbable, antibiotic-loaded hyaluronan and poly-D,L-lactide based hydrogel coating (“Defensive Antibacterial Coating”, DAC, Novagenit, Italy). DAC was reconstructed according to manufacturer indications and loaded with Vancomycin or Vancomycin + Meropenem, according to cultural examinations, and directly spread onto the implant before insertion. This prospective cohort was compared with a retrospective series of 22 consecutive patients, matched for age, sex, host type, site of surgery, that underwent a two stage procedure, using a preformed, antibiotic-loaded spacer (Tecres, Italy) and a cementless implant. The second surgery, for definitive implant placing, was performed only after CRP normalization and no clinical sign of infection. Clinical, laboratory and radiographic evaluation were performed at 3, 6 and 12 months, and every 6 months thereafter. Infection recurrence was defined by the presence of a sinus tract communicating with the joint, or at least two among the following criteria: clinical signs of infections; elevated CRP and ESR; elevated synovial fluid WBC count; elevated synovial fluid leukocyte esterase; a positive cultural examination from synovial fluid; radiographic signs of stem loosening. The two groups did not differ significantly for age, sex, host type and site of surgery (18 knees and 4 hips, respectively). The DAC hydrogel was loaded intra-operatively, according to cultural examination, with vancomycin (14 patients) or vancomycin and meropenem (8 cases). At a mean follow-up of 20.2 ± 6.3 months, 2 patients (9.1%) in the DAC group showed an infection recurrence, compared to 3 patients (13.6%) in the two-stage group. No adverse events associated with the use of DAC or radiographic loosening of the stem were observed at the latest follow-up months. This is the first report on one-stage cementless revision surgery for PJI, performed with a fast-resorbable antibacterial hydrogel coating. Our data, although in a limited series of patients and at a relatively short follow-up, show similar infection recurrence rate after one-stage exchange with cementless, coated implants, compared to two-stage revision. These findings warrant further studies in the possible applications of antibacterial coating technologies to treat implant-related infections

Introduction: The purpose of this paper is to present the results of a prospective study involving one stem design used in primary total hip arthroplasty with three different surface enhancements to include a simple textured geometry, a plasma sprayed coating and an hydroxyapatite (HA) coating. Methods: Between 1990 and 1994, 138 patients underwent primary THA using a simple femoral component. Thirty-eight patients received a textured geometry while 50 were implanted with a HA coated stem and 50, a plasma sprayed stem. The hips were evaluated annually both clinically and radiographically. The results are reported using the Harris Hip Score and the Engh radiographic scale to determine the level of bone ingrowth and type of fixation. Results: The average length of follow up is 8 years 11 months (range: 6 to 10 years). The average postoperative Harris Hip scores were 81.0% for the textured stems, 89.6 for the HA coated stems and 85.7 for the plasma sprayed stems. The revision rates are 13.2% for textured stems, 0% for HA and 5.4 % for plasma sprayed. Radiographic results show that fixation of the 3 surface coatings to be optimal in 100% of HA, 88.2% in plasma sprayed and 84.2% in textured. Discussion and conclusion: At this point in the study, it is obvious that the coating enhancement of choice is hydroxyapatite. The next step in this research will be to match the HA coated stems with a comparable porous coated stem of the same design for further comparison

We carried out a histological study of a proximally hydroxyapatite (HA)-coated femoral component, retrieved after 9.5 years of good function. The HA coating had completely degraded. Bone was in direct contact with the titanium surface in all the areas which had been coated, with no interposing fibrous tissue. There were no signs of particles, third-body wear, adverse tissue reactions or osteolysis. Bone remodelling was evident by the presence of resorption lacunae; tetracycline labelling showed bone laid down six years after implantation. The loss of the HA-coating had no negative effect on the osseo-integration of the stem. We conclude that the HA coating contributes to the fixation of the implant and that its degradation does not adversely affect the long-term fixation

Introduction: This study investigates the survival (and radiological loosening) rates of prostheses following uncemented Total Shoulder Arthroplasties (TSAs) focusing on the glenoid baseplate fixation. Methods: ALL uncemented TSAs inserted in one shoulder unit from 1989 to 2001 were entered onto a database prospectively and the patients monitored to death or failure of the implant, resulting in revision surgery. Over 80% of the surviving implants were monitored on sequential radiographs and the radiological loosening rate was observed. 273 TSAs have been monitored – 193 with a porous coated glenoid baseplate and 80 with a hydroxyapatite coating on top of the porous coating. Results: The Survival rates (%) of the non-HA coated baseplates at 1 to 12 years using the Life Table Method were:− 97, 93, 89, 83, 83, 81, 79, 79, 77, 75, 75 & 75% respectively. The Survival rates for the HA coated glenoid base-plates at 1 to 4 years were 100, 97, 93, & 93% respectively. Failures were predominantly due to mechanical loosening and glenoid disassembly with only 3 cases of infection documented. Thus by 4 years there was a statistically significant improvement in survival of the glenoids. Survival rates were further reduced when radiological loosening was taken into account. The earlier series was analysed to assess the survival of prostheses inserted for RA and OA. The survival rates at 5 and 10 years were 78% & 70% for OA and 96% and 88% for RA. Discussion & Conclusions: This Life Table analysis confirms the early benefit from the use of hydroxy-apatite coating of the glenoid implant of a TSA. Further improvements, particularly in relation to reducing further the small risk of disassembly are underway

The outcome at ten years of 100 Freeman hip stems (Finsbury Orthopaedics, Leatherhead, United Kingdom) retaining the neck with a proximal hydroxyapatite coating in a series of 52 men (six bilateral) and 40 women (two bilateral), has been described previously. None required revision for aseptic loosening. We have extended the follow-up to 20 years with a minimum of 17 years. The mean age of the patients at total hip replacement was 58.9 years (19 to 84). Six patients were lost to follow-up, but were included up to their last clinical review. A total of 22 patients (22 hips) had died, all from causes unrelated to their surgery. There have been 43 re-operations for failure of the acetabular component. However, in 38 of these the stem was not revised since it remained stable and there was no associated osteolysis. Two of the revisions were for damage to the trunnion after fracture of a modular ceramic head, and in another two, removal of the femoral component was because of the preference of the surgeon. In all cases the femoral component was well fixed, but could be extracted at the time of acetabular revision. In one case both components were revised for deep infection. There has been one case of aseptic loosening of the stem which occurred at 14 years. This stem had migrated distally by 7.6 mm in ten years and 8.4 mm at the time of revision at which stage it was found to be rotationally loose. With hindsight this component had been undersized at implantation. The survivorship for the stem at 17 years with aseptic loosening as the endpoint was 98.6% (95% confidence interval 95.9 to 100) when 62 hips were at risk. All remaining stems had a satisfactory clinical and radiological outcome. The Freeman proximally hydroxyapatite-coated femoral component is therefore a dependable implant and its continued use can be recommended

Introduction: One of the main factors in the success of impaction bone grafting (IBG) in revision hip surgery is its ability to resist shear and to form a stable construct. Bone marrow contains multipotent skeletal stem cells and we propose that in combination with allograft will produce a living composite with biological and mechanical potential. In this study we looked at whether coating of the allograft with type 1 collagen followed by seeding with human bone marrow stromal cells (hBMSC) would enhance the grafts mechanical and biological properties. Methods: A control group of plain allograft and three experimental groups where used to determine the effects that collagen and hBMSC have on IBG. The samples where impacted in standardised fashion previously validated to replicate femoral IBG, and cultured in vitro for 2 weeks. The samples then underwent mechanical shear testing and biochemical analysis for DNA content and Osteogenic activity. Results: In isolation, both Collagen coating and seeding with hBMSC significantly enhanced the mechanical properties of the construct compared to the ‘gold standard’ of plain allograft. This was further enhanced (p=0.002) when the two processes are combined both with shear strength (245 vs. 299 kPa) and cohesion between the graft particles (46 vs. 144 kPa). The collagen coated group also showed increased osteogenic cell proliferation. Discussion: This study has shown a role in the improvement of the mechanical properties of IBG coated with collagen and seeded with hBMSC. Collagen coating of IBG is a simple process and translation of the technique into the theatre setting feasible. The improvement in shear strength and cohesion could lead to earlier weight bearing for the patients and allow quicker recovery. The therapeutic implications of such composites auger well for orthopaedic applications. We are currently strengthening the above findings with an in vivo study

Aim. Biofilm-related infections represent a recurrent problem in the orthopaedic setting. In recent years, great interest was directed towards the identification of novel molecules capable to interfere with pathogens adhesion and biofilm formation on implant surfaces. In this study, two stable forms of α-tocopherol, the hydrophobic acetate ester and the water-soluble phosphate ester, were tested in vitro as coating for titanium prostheses. Method. Antimicrobial activity against microorganisms responsible of prosthetic and joints infections was assessed by broth microdilution method. In addition, α-tocopherol esters were evaluated for both their ability to hamper bacterial adhesion and biofilm formation on sandblasted titanium surfaces. Results. Only α-tocopheryl phosphate displayed antimicrobial activity against the tested strains. Both esters were able to significantly interfere with bacterial adhesion and to prevent biofilm formation, especially by Staphylococcus aureus and Staphylococcus epidermidis. The activity of α-tocopheryl phosphate was greater than that of α-tocopheryl acetate. Alterations at membrane levels have been reported in literature1 and may be likely responsible for the interference on bacterial adhesion and biofilm formation shown by α-tocopherol esters. Conclusions. Although further studies are needed to better investigate the mechanisms of action and the spectrum of activity of α-tocopherol esters, these characteristics, together with the positive effect on wound healing and immune response, make these molecules promising candidate for coating in order to prevent implant-associated infections

We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. After 11 to 16 months, 21 screws had been extracted. The extraction torque was recorded. Radiographs were taken to assess fusion and to detect loosening of the screws. At removal, the extraction torques exceeded the upper limit of the torque wrench (600 Ncm) for many HA-coated screws. The calculated mean extraction torque was 29 ± 36 Ncm for the uncoated group, 447 ± 114 Ncm for the partly-coated group and 574 ± 52 Ncm for the fully-coated group. There were significant differences between all three groups (p < 0.001). There were more radiolucent zones surrounding the uncoated screws than the HA-coated screws (p < 0.001). HA coating of pedicle screws resulted in improved fixation with reduced risk of loosening of the screws

In previous studies, we have demonstrated a fibrocartilaginous membrane around hydroxyapatite-coated implants subjected to micromovement in contrast to the fibrous connective tissue which predominates around similarly loaded titanium alloy implants. In the present study, in mature dogs, we investigated the effect of immobilising titanium (Ti)- or hydroxyapatite (HA)-coated implants already surrounded by a movement-induced fibrous membrane and compared the results with those of similar implants in which continuous micromovement was allowed to continue. The implants were inserted in the medial femoral condyles of 14 dogs and subjected to 150 microns movements during each gait cycle. After four weeks (when a fibrous membrane had developed), half the implants were immobilised to prevent further micromovement. The dogs were killed at 16 weeks and the results were evaluated by push-out tests and histological analysis. The continuously loaded Ti-coated implants were surrounded by a fibrous membrane, whereas bridges of new bone anchored the HA-coated implants. The immobilised implants were surrounded by bone irrespective of the type of coating. Push-out tests of the continuously loaded implants showed better fixation of those with HA coating (p < 0.001). The immobilised Ti-coated implants had four times stronger fixation than did continuously loaded Ti-coated implants (p < 0.01) but there was no equivalent difference between the two groups of HA-coated implants. The amount of bone ingrowth was greater into immobilised HA-coated implants than into immobilised Ti-coated implants (p < 0.01). Two-thirds of the HA coating had been resorbed after 16 weeks of implantation, but 25% of this resorbed HA had been replaced by bone.(ABSTRACT TRUNCATED AT 250 WORDS)

One cementless cup which had porous outer surface with Apatite-Wollastonite glass ceramic (AWGC) coating, was revised 13 years after primary THA because of massive osteolysis expanded to medial iliac wall along the screws. While many retrieved studies of hydroxyapatite-coated cup have been reported, there has been no report on the retrieved cup with AWGC coating. The purpose of this study was to describe this rare case in detail, confirm the bone ingrowth to the porous cup, and discuss on the effectiveness of porous surface with AWGC coating. Case. The patient was a 64 old woman and complained of chronic mild pain around her left groin region. X-ray examination revealed that osteolysis had been expanding around the screws and extended proximally. The revision surgery was performed for the massive osteolysis through Hardinge antero-lateral approach. The retrieved implants included a cementless cup made of titanium alloy (QPOC cup, Japan Medical Materirals Inc.(JMM) Osaka, Japan), the outer surface of which was plasma-sprayed with titanium for porous formation and coated with AWGC in the deep layer. It was found that the polyethylene liner was destructed partially in the supero-lateral portion, but the cup was well fixed to the bone. The bone-attached area was found to be dispersed over the porous surface of the hemispherical cup. Histological examination revealed that matured bony tissue intruded into the porous surface of the cup, and contacted to bone directly, which was also demonstrated in the back-scattered electron image. It was also demonstrated that there were residual silicon (Si) rich regions on the porous surface by the SEM-EDX analysis, which indicated that constituents of AWGC still remained on the surface. On the other hand, the results of elementary analyses in the Si rich regions varied among the sections, which probably indicated that the extent of degradation and absorption of AWGC varied among the sections. AWGC was one of the bioactive ceramics and reported to have an ability to bond to bone earlier than hydroxyapatite (HA). In the present case, though massive osteolysis occurred with aggressive wear, it did not expand on the porous surface, and rather progressed along the smooth surface of the screws. Considering that there are many clinical studies reporting poor clinical results of HA-coated smooth cups, bioactive ceramic coating may function well and bring superior clinical results when combined with porous coated substrate. In our study, though the cause of massive polyethylene wear and intrapelvic giant osteolysis could not be revealed, the porous cup with AW-GC bottom coating was well fixed and gained bone-ingrowth at the porous surface under osteolytic conditions, which may demonstrate the long-term durability of this surface treatment

Introduction: The aim of this study is long term comparison of hydroxyapatite (HA) coating and porous (PO) coating in an identical stem design. Material and Methods: 100 consecutive hips from 86 patients scheduled for uncemented primary arthroplasty were quasi-randomized to receive a titanium-alloy anatomic PROFILE stem (DePuy, Warsaw, IN), HA coated in every second hip and PO coated in the remainder 50 hips. Patients receiving bilateral total hip arthroplasty were implanted an HA coated stem in one and a PO coated in the contralateral hip. All surgeries were performed by the posterolateral approach by 2 surgeons (the author PBT being one of them). The acetabular component was either an AML+ or a Duraloc 300 implant with a cobalt chrome 28mm head (DePuy, Warsay, IN). 15 to 18 years postoperatively these patients and their hip radiographs were examined by an independent observer (WD) to establish the long term survival, clinical and radiographical performance of this stem and especially to compare the two coatings. The Harris hip score was employed for clinical evaluation. Results: 16 years and 3 months (range 15y 0m – 17y 8m) postoperatively 21 patients with 23 hips had died and 4 hips (2HA/2 PO) had been revised. This leaves 62 patients with 73 hips (34 HA/39 PO) for evaluation. Life tables showed 18 years cumulative survival (free of revision of any reason) of 95.8% for HA and 95.5% for PO. 18 years cumulative survival (free of revision for aseptic loosening) were 95.8% for HA and 97.5% for PO. There were no infections in either group. Mean HHS was 83.4 ± 14.8 in HA and 86.8 ± 11.5 in PO (P = 0.32). Mean pain score was 39.1 ± 9.4 in HA and 40.9 ± 6.7 in PO (P = 0.69). Radiographs showed osseointegration of the stem except in 1 HA and in 2 PO stems. Lucencies/osteolytic scalloping were only seen in zone 1 and 7. Significant bone remodeling changes were seen. Ectopic ossification developed in 1/3 of hips non progressive stem subsidence of 2 mm were measured in a few hips. Conclusion: This prospective quasi-randomized study show excellent long term performance and survival of the titanium-alloy anatomic PROFILE stem in primary hip arthroplasty in patients < 66 years with no significant differences between HA and PO coating

Degradable implants made of magnesium alloys as osteosynthesis material for weight-bearing bone are at present a main research area. With regards to biocompatibility, a MA with 0.8 wt. % Calcium (MgCa(0.8)) has been shown to possess advantageous qualities. Long-term investigations in animal models however, showed that the degradation rate of this magnesium alloy was relatively rapid and therefore the mechanical properties decreased early during the implantation period. An implant for osteosynthesis in weight-bearing bones however needs to exhibit adequate stability during the first few weeks of fracture healing. This cannot sufficiently be assured by the MgCa(0.8) alloy. It has been suggested in the literature, that the degradation rate of MA could be reduced using a fluoride coating. Therefore it was the aim of this study to investigate, whether the coating of degradable MA MgCa(0.8) implants with magnesium fluoride layer leads to decreased degradation rate and in consequence to an improvement of the mechanical properties using an animal model. Extruded pins (2.5 mm x 25 mm) of MgCa(0.8) were produced. Twenty of these pins were coated with a fluoride layer by submerging the implants in a bath with 40% hydrofluoric acid. With this procedure, the pins were covered with a thin (150–200μm thickness) MgF2 layer. Coated and uncoated pins were intramedullary implanted into both tibiae of ten New Zealand White Rabbits. Three and six months after surgery five animals of each group were euthanized and the tibiae were explanted for further analysis. Micro-computed tomography (μCT) and scanning electron microscopy (SEM) were performed of the explanted pins. In order to investigate changes of the mechanical properties, 3-point bending tests were carried out with MgCa(0.8) pins at the initial state and with the explanted pins, with and without the fluoride layer at both times. In addition, the mass loss of the pins was determined. To evaluate the degradation process of the MgCa(0.8) pins with the MgF2 layer, micrographs and element analyses (EDX) were accomplished after the three point bending tests. During the investigation period, the rabbits showed no signs of lameness or pain. The MgCa(0.8) alloy and the MgCa(0.8) alloy with the MgF2 layer showed significant differences regarding the mechanical properties in dependence of the implantation duration. Generally, the mechanical resistance decreases with increasing implantation time. The 3-point bending test showed, that the values of maximal force of the coated MgCa(0.8) implants after three month implantation duration were lower than those of the uncoated implants. After an implantation duration of six months, the values of maximal force of the implants coated with MgF2 were higher than those of the uncoated implants. Regarding the implant mass, the coated and uncoated MgCa(0.8) implants showed a loss of mass during the implantation period. The mass loss of the coated implants was only slightly lower. This difference was minor after three months and more obviously after six months. With μCT new endosteal bone formation could be seen close to all implants. A decrease of the cross section dimension could be demonstrated with μCT and SEM and changes of the surfaces due to pitting corrosion could be demonstrated in both the coated and uncoated MgCa(0.8) implants on the whole length, which was more obvious after six months. The micrographs showed corroded surfaces but not preferred corrosion on the grain boundaries. The element analysis showed a degradation layer on the implant surface, which was more bulky on implants after six month implantation duration. The mapping shows, that the fluoride molecules are clearly visible after three and six months around the margin of the implant. With the results of this study it could be demonstrated, that the coating of the MgCa(0.8) implants with a flouride layer did not have a positive influence on the mechanical properties and the degradation rate of the implant in the bone. This leads to the conclusion that MgF2-coated MgCa(0.8) implants are also not suitable for osteosynthesis in weightbearing bones

We have studied the beneficial effects of a hydroxyapatite (HA) coating on the prevention of the migration of wear debris along the implant-bone interface. We implanted a loaded HA-coated implant and a non-coated grit-blasted titanium alloy (Ti) implant in each distal femoral condyle of eight Labrador dogs. The test implant was surrounded by a gap communicating with the joint space and allowing access of joint fluid to the implant-bone interface. We injected polyethylene (PE) particles into the right knee three weeks after surgery and repeated this weekly for the following five weeks. The left knee received sham injections. The animals were killed eight weeks after surgery. Specimens from the implant-bone interface were examined under plain and polarised light. Only a few particles were found around HA-coated implants, but around Ti implants there was a large amount of particles. HA-coated implants had approximately 35% bone ingrowth, whereas Ti implants had virtually no bone ingrowth and were surrounded by a fibrous membrane. Our findings suggest that HA coating of implants is able to inhibit peri-implant migration of PE particles by creating a seal of tightly-bonded bone on the surface of the implant

In two-stage revision surgery of infected joint prosthesis, temporary bone cement spacers have been used for several years. By adding antibiotics to the cement, high local antibiotic concentrations that exceed the minimum inhibiting and bactericidal concentration of the respective pathogen during the first days after surgery, are achieved. Currently, aminoglycosides (e.g. gentamicin and tobramycin), as well as glycopetides (e.g vancomycin) are used as antibiotic agents and mixed into the acrylic cement. In order to increase the quantity of active antibiotic substances, we established a novel surgical technique of additional superficial vancomycin coating (SVC) of temporary bone cement spacer. The aim of this study was to analyze the safety of this method by measuring postoperative joint and serum vancomycin concentrations, as well as the creatinine levels. We reviewed prospectively collected data on all patients, which were treated by explanting the prosthetic components, following temporary spacer implantation and SVC between 05/2013 and 04/2015 at the Department of Orthopedic Surgery, Medical University of Graz. In total 13 patients were treated by addition SVC during the study period. Before hardening, vancomycin powder (2 grams) was pressed manually onto the surface of the bone cement. Vancomycin levels were obtained from drains and blood samples on postoperative days 1 to 5. Forty-six blood serum samples and 52 drain fluid samples were available for further. On postoperative day one to five, a median serum vancomycin level of < 2.0 μg/mL was present (range <2.0 – 3.9). The highest median vancomycin level from the drain was documented on postoperative day 1 with a value of 388.0 μg/mL (range 44.4–1650.0), continually decreasing until postoperative day 4. After SVC, neither an anaphylactic reaction nor side effects such as a red man syndrome, fever and chills were observed. Furthermore, no patient complained about subjective hearing loss. No serum creatinine increase of 0.5 mg/dL from creatinine baseline value or a ≥50% increase from baseline was detected. After a median of 64 days (range 18–82), the temporary cement spacer was explanted followed by prosthesis implantation. During this time no reinfection occurred. One patient suffered from a dislocation of the spacer with a distal femur fracture and was therefore re-operated after 18 days. Powdered vancomycin as an additional superficial coating of bone cement spacer results in much higher local antibiotic concentrations than in conventional spacers. The newly introduced method is feasible, safe and promising to enhance local inhibiting concentrations of vancomycin

Background: As the understanding of bone repair mechanics has advanced the integrity of the bone pin interface has emerged as a key factor in determining the success of external fracture fixation. The benefits of using pins coated with Hydroxyapatite (HA) are well documented however the thickness of the conventional plasma spray coating precludes its use for modification of the surface of fine features in implants. Consequently new electro-chemical techniques for pre-coating implants with a ‘biomimetic’ HA layer using simulated body fluids (SBF) have been pioneered. In this study we test the hypothesis that varying the technique for deposition of HA by electrolysis of SBF alters the morphology of the HA surface which will modify the level of osseointegration. Method: Three alternative methods of HA coating the Barerre, Redepenning and Kumar techniques were compared. Tantalum coated stainless steel pins were coated then used to stabilise a mid-diaphyseal osteotomy in three sheep using an orthofix fixator for a period of ten weeks. Insertion and extraction torques were measured to calculate the pin performance index (PPI). Sections of the bones were then examined using scanning electron microscopy to determine the percentage of bone in contact with the pin surface and the percentage of new bone formation. Results: The different coating protocols resulted in different HA crystal morphologies. The extraction torque exceeded the insertion torque for both the Barerre and Redepenning methods and their PPI exceeds that of plasma spray coatings. The Redepenning technique was shown to perform sig-nificantly better than both the Barerre (p=0,001) and Kumar (p=0,001) techniques with 49.4% of the pin surface in contact with bone. These results were mirrored on analysis of new bone formation with the Redepen-ning technique showing 70.2% of new bone formation compared to the Barerre (55.4%) and Kumar (53.8%) methods. Conclusion: These results indicate that the Redepenning technique is the most effective for creating a bio mimetic HA coating in terms of bonding to bone and promoting new bone formation. This technique holds significant advantages over the conventional plasma spray technique for example the coating thickness can be easily controlled and additional proteins such as bone morphogenic proteins and antibiotics can be incorporated. It may therefore represent a new era in the use of HA coating

Cementless distally locked stems were introduced in revision hip arthroplasty (RTHA) in the late 1980s to deal with severe femoral bone loss. These implants have not been assessed over the long-term, particularly the influence of the design and porous coating. Therefore we performed a retrospective case-control study at a minimum 10-years' follow-up comparing the straight Ultime™ stem with 1/3 porous coating versus the anatomical Linea™ stem with 2/3 proximal coating with hydroxyapatite. We performed a single-center case-control study measuring survival, function based the Harris and Oxford-12 scores, and rate of thigh pain. X-rays were done at regular intervals and at follow-up. No femoral bone graft was used at insertion. The two groups were comparable in terms of age, sex and follow-up (mean 12.2 years in Ultime and 10.8 years in Linea cohorts); however they differed in the severity of bone loss therefore the results were adjusted according to this variable. Ten-year survival considering revision for any reason was 63.5% ± 5.4 for Ultime and 91.6% ± 2.7 for Linea (p < 0.001). Merle d'Aubigné scores and Oxford-12 were higher in the Linea group 82.9 ± 12.4 and 26.3/48, respectively, versus 69.5 ± 16 and 21/48 in the Ultime group (p < 0.001). Thigh pain was observed in 30% of Ultime cases versus 3% of Linea cases. Bone reconstruction measured via cortical thickness was better in the Linea group and correlated to metaphyseal filling at insertion. This study confirms the benefits of using of locked stems in RTHA with severe bone loss. Better metaphyseal filling and optimized porous coating help to minimize thigh pain and the revision rate

Introduction: Impaction bone grafting (IBG) using fresh frozen morsellised allograft is considered by many as the method of choice for replacing lost bone stock encountered during revision hip surgery. Bone marrow contains multipotent skeletal stem cells which have the potential to differentiate down a number of different cell lineages including osteoblasts, chondrocytes and adipocytes. In IBG it is desirable for as many as possible to go on to form bone rather than fibrous tissue to form a solid osseous construct. Whilst it is possible to push cells down the osteogenic lineage in vitro, some of these methods (e.g. the addition of Dexamethasone) are not translatable to clinical practice due to undesirable side effects. In this study we test the hypothesis that by coating the allograft with type 1 Collagen prior to seeding with human bone marrow stromal cells (hBMSC), the cellular adhesion and proliferation down an osteogenic lineage can be increased, leading to improved mechanical and biological properties of the IBG composite. Methods: A control group of plain allograft and three experimental groups where used to determine the effects that collagen and hBMSC have on IBG (both individually and in combination). The samples where impacted in standardised fashion previously validated to replicate Femoral IBG, and cultured in vitro for 2 weeks. The samples then underwent mechanical shear testing giving a family of stress strain curves for each group, from which a Mohr coulomb failure curve can be plotted. Using the Mohr Coulomb failure equation τ = σ tanΦ + c, the shear strength (τ), Internal friction angle (tanΦ) and inter particulate cohesion (c) can then be calculated. Biochemical analysis was also performed for DNA content and Osteogenic activity. Results: Mechanical shear testing demonstrated a significant improvement (p=0.002) in the grafts ability to resist shear with the coating of Collagen and seeding with hBMSC (245 vs 299 kPa) as well as improved cohesion between the bone graft particles (46 vs 144 kPa). Regression analysis of the shear strength showed a linear increase with compressive stress (R2 > 0.98) for all groups, indicating that the grafts satisfied the Mohr Coulomb failure law. In the two groups seeded with cells, the collagen coated group also showed increased osteogenic cell activity compared to the plain allograft. Conclusion: This study has shown a role in the improvement of the mechanical and biological properties of IBG coated with type 1 Collagen and seeded with hBMSC. Collagen coating of IBG is a facile process and translation of the technique into the theatre setting feasible. The improvement in shear strength and cohesion could lead to earlier weight bearing for the patients and allow quicker recovery. The therapeutic implications of such composites auger well for orthopaedic applications. We are currently strengthening the above findings with an in vivo study

Introduction: Various antibiotic coatings have been proposed to prevent bacteria colonization and infection of orthopaedic implants. While most of the available technologies seem to provide an effective implant protection from infection, unknown long-term effects of antibiotic coatings raise some concerns for extensive application. Aim of the present study was to develop and test a new fast-resorbable antibacterial carrier to be used as a temporary coating to prevent early bacteria colonization of metallic implants. Methods: The patented tested hydrogel is a co-polimer comprising hyaluronic acid (HA) and a biocompatible polyester (poly-lactic acid) with or without polyethylene glycol chains to further modulate hydrophilicity and anti-fouling characteristics of the compound. The HA derivative is then added to water and mixed, just before its use, with the chosen antibacterial agent. For the purpose of this study, different HA-PLA derivatives have been tested, with two vancomycin and tobramycin concentrations and manually spread to uniformly cover the surface of a titanium specimen. To evaluate the release of vancomycin or tobramycin, high performance chromatographic analysis (HPLC) was carried out. Results: Antibacterial hydrogels provided vancomycin release ranging from 47 % to 80 % in two hours to 100 % (complete release) in 24 to 72 hours, with antibiotic concentrations up to 400 times the minimum inhibiting concentration. The combined release of the two antibiotics (1 % w/v) showed 26.8 % release of vancomycin and 35.8 % of tobramycin at 2 hours and complete release at 72 hours. Doubling antibiotic concentration (2 % w/v), yielded 56.6 % and 76.6 % antibiotic release, respectively for vancomycin and tobramycin at 2 hours and complete release at 48 hours. Discussion and Conclusion: HA chemical derivatization with polyesters leads to the formation of copolymers which can be used to produce antibacterial hydrogels with promising applications in the orthopedic field. These antibacterial hydrogels are in fact easily prepared and spread over a surface, showing the ability of releasing high concentrations of antibiotics for a desired, limited, period of time. Adding antibiotics to the hydrogel just before its use, allows customized antibiotic choice and dosing, avoiding shelf-life problems

Background: Hydroxyapatite (HA) coating is widely used for total hip arthroplasty as it has been suggested to improve implant ingrowth and long-term stability. However, the evidence behind the use of HA in femoral stems is ambiguous. Methods: We investigated a non-cemented, tapered titanium femoral stem that was available either with or without HA coating. This stem had been used in 3,116 total hip arthroplasties (THAs) in 2,608 patients registered in the Swedish Hip Arthroplasty Register (1992–2007). Kaplan-Meier survival analysis and a Cox regression model including type of coating, age, sex, primary diagnosis, and the type of cup fixation were used to calculate adjusted risk ratios (RR) of the risk for revision for various reasons. Results: 63.7% of the stems were coated with HA, 36.3% were uncoated. It was found that the investigated HA-coated stem had an excellent 10-year survivorship of 97.7% (95% CI 96.5–98.9), and that the stem without HA coating had a 10-year survivorship of 97.6% (95% CI 96.2–99.0) when revision due to any reason was defined as the endpoint. There was no significant difference between these two groups (p> 0.05, log rank Mantel-Cox). A Cox regression model showed that the presence of HA coating did not significantly influence the risk of stem revision due to any reason (RR 1.3; 95% CI 0.7–2.4), or due to aseptic loosening (RR 1.0; 95% CI 0.3–3.4). The risk for revision due to infection, dislocation, or fracture was also not affected by the presence of HA coating. Interpretation: Our results show HA coating of this non-cemented tapered stem with excellent 10-year survivorship does not affect the risk for revision. The assumed beneficial effect of HA coating of femoral stems in total hip arthroplasty is thus questionable

The purpose of this study was to evaluate the clinical outcome of a hydroxyapatite (HA)-coated tapered stem and to assess bone remodelling of the proximal femur using quantitative computed tomography osteodensitometry. Fifty consecutive hips were managed with total hip replacement using the Cerafit Multicone H-A.C. stem with HA coating and the Cerafit Triradius-M press-fit cup (Ceraver Osteal, Paris, France). The mean follow-up was 3 years (range, 2.9 to 4 years). Current criteria were used for clinical and radiological assessment. Forty-nine hips (98%) were clinically rated good or excellent. The mean preoperative Harris Hip Score was rated 57, and it has improved to 96 at the time of follow-up. The radiographs showed stable fixation by bone ingrowth in all hips. Fifteen patients (15 hips) were eligible for osteodensitometry. The mean decrease of the overall bone density (BD) in the metaphyseal portion of the femur 3 years after insertion of the stem was rated 14.21%, and the mean decrease of the cortical BD was rated 15.52%. The mean decrease of the overall BD in the diaphyseal portion of the femoral component was rated 10.00%, and the mean decrease of cortical BD was rated 7.76%. Little changes were observed underneath the tip of the stem. The clinical and radiological outcomes of the tapered stem with HA coating at a mean follow-up of 3 years compares favourably with other reports. Results of osteodensitometry show less proximal femur BD loss in comparison to similar investigations performed using uncemented stems

We report the histological findings in post-mortem specimens obtained ten days, 17 days and seven weeks after implantation of hydroxyapatite-coated femoral components of hip arthroplasties. There was early deposition of woven bone on the hydroxyapatite ceramic, identical to that deposited on surviving cancellous trabeculae. The space between these deposits became bridged from both sides by new trabeculae, and there was no evidence of an inflammatory reaction or of fibrous tissue formation. The use of an hydroxyapatite coating seems to allow early, sound, secondary fixation of implants

The design of the femoral prosthesis in cementless total hip arthroplasty is known to affect the initial strains in the cortex during implantation and in the early postoperative time period. High strains have a direct influence on periprosthetic fracture. This study compares the existing ABGII stem, which is proximally coated with a grit blasted titanium surface with hydroxyapatite coating with a prototype that has a rougher titanium plasma spray proximal coating. The Australian National Joint registry results 2011 reported the ABG2 femoral component cumulative percent revision (CPR) of 6.5 (93.5% survival), which compares favourably with equivalent stems with 10 year CPR data such as the Taperloc 6.6 and Corail 7.3. Six pairs of fresh-frozen cadaveric femurs were mounted in blocks according to ISO guidelines in single leg stance setup. Five strain gauges were attached around the neck of the femur and then prepared according to routine operative techniques to accept the femoral prosthesis. Cortical strains were measured during insertion of the prosthesis with an instrumented mallet attached to an accelerometer. Subsequently, force-displacement readings were taken during cyclical loading on a servo-hydraulic machine and finally the stems were tested to failure. Our results showed significantly less strain during cyclical loading of the stem with increased surface roughness (p < 0.05). They also showed no significant differences loads/strains during impaction (p = 0.159), no significant difference in micromotion (p = 0.148) and no significant difference in load-to-failure (p = 0.37)

We studied two groups of femoral hip prostheses: 43 TiAlV ridged press-fit stems, and 26 with similar stems coated with hydroxyapatite on the proximal half. At one year, radiological measurement showed a mean downward migration of 0.99 mm for the TialV prostheses and 0.12 mm for the HA-coated prostheses (p = 0.0002). Hydroxyapatite coating appeared to provide effective bio-active supplementary fixation

Aims: To evaluate clinical and radiographicl results of hydroxyapatite versus porous coated stems in total hip arthroplasty. Methods: A consecutive randomized series of 447 cementless Titanium prostheses were prospectically studied. The stems (Synergy-Smith& Nephew) were different for the proximal 1/3 hydroxyapatite (HA=268) or titanium porous coating (PC=179) Same cup and ball head were used. Clinical (HHS/Womac) and radiological assessments (Enghñs criteria) were obtained before and after surgery (mean F-U=27,05 months). Results: The clinical outcomes showed a signiþcant improvement in both groups. Bone ingrowth was present in 100% (HA) and 96% (PC) and stable þbrous ingrowth in 4% (PC). Cortical hypertrophy and heterotopic ossiþcation (Brooker 1) were prevalent in HA without limitation of ROM or pain. Stress shielding was equivalent. Nor osteolysis neither subsidence were identiþed. Fractures occurred in 8 cases (HA=6/PC=2) and dislocation in 3 cases. Conclusions: In this study the two types of stems showed good comparable clinical results. The complication were not related to the coating. HA coated prosthesis showed faster osseointegration, and enhanced bone ingrowth. The earlier bone-stable integration obtained in the HA group may be predictive of a lesser degree of osteolysis in the future

We describe the survival at ten years of 100 femoral components of the Freeman hip prosthesis. It is proximally hydroxyapatite (HA)-coated and was fixed without cement. Radiological assessment identified radiolucent lines (RLLs) and lytic lesions and was used to measure migration. The criterion of failure was revision or impending revision for aseptic femoral loosening. No femoral components were revised or are awaiting revision for aseptic loosening, giving 100% survival at ten years (95% confidence interval, 95.7 to 100), although 59 were at risk at ten years. Two components were revised for fracture of a ceramic head with damage to the trunnion. Although well fixed in each, for survival analysis we evaluated the hip as if the patient had died. Twelve acetabular components were revised and at each operation the femoral component was found to be well fixed, was not disturbed and remained in the survival analysis. Three patients were lost to follow-up, and 12 died with well-functioning prostheses. Radiologically, all except one of the components appeared to be well fixed with no RLLs and no lytic lesions at the latest follow-up. The mean vertical migration was 0.4 mm at one year, 0.8 mm at two years and 1.4 mm at ten years. One component had migrated 7.6 mm at ten years (2.1 mm in year 1) and developed RLLs in Gruen zones I and II. The symptoms, however, were only minor and revision was not indicated. Our study has shown that proximal HA coating gives effective fixation for a femoral component

One concern about the fixation of HA-coated implants is the possible disintegration of the surface, with the migration of HA granules into the joint space, producing third-body wear. We report a study of six revisions of HA-coated polyethylene RM cups at 9 to 14 years after successful primary arthroplasty. In all six hips, we found HA granules embedded in the articulating surface of the polyethylene, with abrasive wear of the cup and the metal femoral head. The cup had loosened in four hips and three showed severe osteolysis of the proximal femur. Third-body wear due to HA particles from implant coating may produce severe clinical problems with few early warning signs. Further clinical, radiological and histological observations are needed to determine the possible incidence of this late complication in the various types of coating of a variety of substrates