Aims. Due to their radiolucency and favourable mechanical properties, carbon fibre nails may be a preferable alternative to titanium nails for oncology patients. We aim to compare the surgical characteristics and short-term results of patients who underwent intramedullary fixation with either a titanium or carbon fibre nail for pathological long-bone fracture. Methods. This single tertiary-institutional, retrospectively matched case-control study included 72 patients who underwent prophylactic or therapeutic fixation for pathological fracture of the humerus, femur, or tibia with either a titanium (control group, n = 36) or carbon fibre (case group, n = 36) intramedullary nail between 2016 to 2020. Patients were excluded if intramedullary fixation was combined with any other surgical procedure/fixation method. Outcomes included operating time, blood loss, fluoroscopic time, and complications. Fisher’s exact test and Mann-Whitney U test were used for categorical and continuous outcomes, respectively. Results. Patients receiving carbon nails as compared to those receiving titanium nails had higher blood loss (median 150 ml (interquartile range (IQR) 100 to 250) vs 100 ml (IQR 50 to 150); p = 0.042) and longer fluoroscopic time (median 150 seconds (IQR 114 to 182) vs 94 seconds (IQR 58 to 124); p = 0.001). Implant complications occurred in seven patients (19%) in the titanium group versus one patient (3%) in the carbon fibre group (p = 0.055). There were no notable differences between groups with regard to operating time, surgical wound infection, or survival. Conclusion. This pilot study demonstrates a non-inferior surgical and short-term clinical profile supporting further consideration of carbon fibre nails for pathological fracture fixation in orthopaedic oncology patients. Given enhanced accommodation of imaging methods important for oncological surveillance and radiation therapy planning, as well as high tolerances to fatigue stress, carbon fibre implants possess important oncological advantages over titanium implants that merit further prospective investigation. Level of evidence: III, Retrospective study. Cite this article: Bone Jt Open 2022;3(8):648–655

Aims. This study examined whether systemic administration of melatonin would have different effects on osseointegration in ovariectomized (OVX) rats, depending on whether this was administered during the day or night. Methods. In this study, a titanium rod was implanted in the medullary cavity of one femoral metaphysis in OVX rats, and then the rats were randomly divided into four groups: Sham group (Sham, n = 10), OVX rat group (OVX, n = 10), melatonin day treatment group (OVX + MD, n = 10), and melatonin night treatment group (OVX + MN, n = 10). The OVX + MD and OVX + MN rats were treated with 30 mg/kg/day melatonin at 9 am and 9 pm, respectively, for 12 weeks. At the end of the research, the rats were killed to obtain bilateral femora and blood samples for evaluation. Results. Micro-CT and histological evaluation showed that the bone microscopic parameters of femoral metaphysis trabecular bone and bone tissue around the titanium rod in the OVX + MD group demonstrated higher bone mineral density, bone volume fraction, trabecular number, connective density, trabecular thickness, and lower trabecular speculation (p = 0.004) than the OVX + MN group. Moreover, the biomechanical parameters of the OVX + MD group showed higher pull-out test and three-point bending test values, including fixation strength, interface stiffness, energy to failure, energy at break, ultimate load, and elastic modulus (p = 0.012) than the OVX + MN group. In addition, the bone metabolism index and oxidative stress indicators of the OVX + MD group show lower values of Type I collagen cross-linked C-telopeptide, procollagen type 1 N propeptide, and malondialdehyde (p = 0.013), and higher values of TAC and SOD (p = 0.002) compared with the OVX + MN group. Conclusion. The results of our study suggest that systemic administration with melatonin at 9 am may improve the initial osseointegration of titanium rods under osteoporotic conditions more effectively than administration at 9 pm. Cite this article: Bone Joint Res 2022;11(11):751–762

Aims. The efficacy of saline irrigation for treatment of implant-associated infections is limited in the presence of porous metallic implants. This study evaluated the therapeutic efficacy of antibiotic doped bioceramic (vancomycin/tobramycin-doped polyvinyl alcohol composite (PVA-VAN/TOB-P)) after saline wash in a mouse infection model implanted with titanium cylinders. Methods. Air pouches created in female BalBc mice by subcutaneous injection of air. In the first of two independent studies, pouches were implanted with titanium cylinders (400, 700, and 100 µm pore sizes) and inoculated with Staphylococcus aureus (1 × 10. 3. or 1 × 10. 6. colony-forming units (CFU)/pouch) to establish infection and biofilm formation. Mice were killed after one week for microbiological analysis. In the second study, pouches were implanted with 400 µm titanium cylinders and inoculated with S. aureus (1 × 10. 3. or 1 × 10. 6. CFU/pouch). Four groups were tested: 1) no bacteria; 2) bacteria without saline wash; 3) saline wash only; and 4) saline wash plus PVA-VAN/TOB-P. After seven days, the pouches were opened and washed with saline alone, or had an additional injection of PVA-VAN/TOB-P. Mice were killed 14 days after pouch wash. Results. The first part of the study showed that low-grade infection was more significant in 400 µm cylinders than cylinders with larger pore sizes (p < 0.05). The second part of the study showed that saline wash alone was ineffective in eradicating both low- and high-grade infections. Saline plus PVA-VAN/TOB-P eradicated the titanium cylinder-associated infections, as manifested by negative cultures of the washouts and supported by scanning electron microscopy and histology. Conclusion. Porous titanium cylinders were vulnerable to bacterial infection and biofilm formation that could not be treated by saline irrigation alone. Application of PVA-VAN/TOB-P directly into the surgical site alone or after saline wash represents a feasible approach for prevention and/or treatment of porous implant-related infections. Cite this article: Bone Joint Res 2024;13(11):622–631

Aims. When performing revision total hip arthroplasty using diaphyseal-engaging titanium tapered stems (TTS), the recommended 3 to 4 cm of stem-cortical diaphyseal contact may not be available. In challenging cases such as these with only 2 cm of contact, can sufficient axial stability be achieved and what is the benefit of a prophylactic cable? This study sought to determine, first, whether a prophylactic cable allows for sufficient axial stability when the contact length is 2 cm, and second, if differing TTS taper angles (2° vs 3.5°) impact these results. Methods. A biomechanical matched-pair cadaveric study was designed using six matched pairs of human fresh cadaveric femora prepared so that 2 cm of diaphyseal bone engaged with 2° (right femora) or 3.5° (left femora) TTS. Before impaction, three matched pairs received a single 100 lb-tensioned prophylactic beaded cable; the remaining three matched pairs received no cable adjuncts. Specimens underwent stepwise axial loading to 2600 N or until failure, defined as stem subsidence > 5 mm. Results. All specimens without cable adjuncts (6/6 femora) failed during axial testing, while all specimens with a prophylactic cable (6/6) successfully resisted axial load, regardless of taper angle. In total, four of the failed specimens experienced proximal longitudinal fractures, three of which occurred with the higher 3.5° TTS. One fracture occurred in a 3.5° TTS with a prophylactic cable yet passed axial testing, subsiding < 5 mm. Among specimens with a prophylactic cable, the 3.5° TTS resulted in lower mean subsidence (0.5 mm (SD 0.8)) compared with the 2° TTS (2.4 mm (SD 1.8)). Conclusion. A single prophylactic beaded cable dramatically improved initial axial stability when stem-cortex contact length was 2 cm. All implants failed secondary to fracture or subsidence > 5 mm when a prophylactic cable was not used. A higher taper angle appears to decrease the magnitude of subsidence but increased the fracture risk. The fracture risk was mitigated by the use of a prophylactic cable. Cite this article: Bone Jt Open 2023;4(7):472–477

Aseptic inflammation is the main factor causing aseptic loosening of artificial joints. Studies have shown that inflammatory cells can activate STING (stimulator of interferon genes, STING) after being stressed. This study aims to explore the specific mechanism of STING in aseptic loosening of artificial joints, and provide new strategies for disease prevention. Titanium particles with a diameter of 1.2-10 μm were prepared to stimulate macrophages (RAW 264.7) to simulate the periprosthetic microenvironment. A lentiviral vector targeting the STING gene was designed and transfected into macrophages to construct a cell line targeting STING knockdown. The expression and secretion levels of TNF-α were detected by qPCR and ELISA, the activation levels of inflammatory pathways (NF-κB, IRF3, etc.) were detected by western blot, and the nucleus translocation of P65 and IRF3 was observed by cellular immunofluorescence. After titanium particles stimulated macrophages, qPCR and ELISA showed that the transcription and secretion levels of TNF-α were significantly increased. Western blot showed that titanium particle stimulation could increase the phosphorylation levels of NF-κB and IRF3 pathways. While knockdown of STING can significantly reduce titanium particle-induced TNF production, attenuate the activation levels of NF-κB and IRF3 pathways as well as the nucleus translocation of P65 and IRF3. Conclusions: STING positively regulates the level of inflammation in macrophages induced by titanium particles, and targeted inhibition of STING can reduce inflammation, which may delay the progression of aseptic loosening of artificial joints

Aims. Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but the solid metal implants disrupt the natural distribution of stress and strain which can lead to bone loss over time. This generates problems if the implant needs to be revised. This study investigates whether titanium lattice UKA and TKA implants can maintain natural load transfer in the proximal tibia. Methods. In a cadaveric model, UKA and TKA procedures were performed on eight fresh-frozen knee specimens, using conventional (solid) and titanium lattice tibial implants. Stress at the bone-implant interfaces were measured and compared to the native knee. Results. Titanium lattice implants were able to restore the mechanical environment of the native tibia for both UKA and TKA designs. Maximum stress at the bone-implant interface ranged from 1.2 MPa to 3.3 MPa compared with 1.3 MPa to 2.7 MPa for the native tibia. The conventional solid UKA and TKA implants reduced the maximum stress in the bone by a factor of 10 and caused > 70% of bone surface area to be underloaded compared to the native tibia. Conclusion. Titanium lattice implants maintained the natural mechanical loading in the proximal tibia after UKA and TKA, but conventional solid implants did not. This is an exciting first step towards implants that maintain bone health, but such implants also have to meet fatigue and micromotion criteria to be clinically viable. Cite this article: Bone Joint Res 2022;11(2):91–101

Aims. This study intended to investigate the effect of vericiguat (VIT) on titanium rod osseointegration in aged rats with iron overload, and also explore the role of VIT in osteoblast and osteoclast differentiation. Methods. In this study, 60 rats were included in a titanium rod implantation model and underwent subsequent guanylate cyclase treatment. Imaging, histology, and biomechanics were used to evaluate the osseointegration of rats in each group. First, the impact of VIT on bone integration in aged rats with iron overload was investigated. Subsequently, VIT was employed to modulate the differentiation of MC3T3-E1 cells and RAW264.7 cells under conditions of iron overload. Results. Utilizing an OVX rat model, we observed significant alterations in bone mass and osseointegration due to VIT administration in aged rats with iron overload. The observed effects were concomitant with reductions in bone metabolism, oxidative stress, and inflammation. To elucidate whether these effects are associated with osteoclast and osteoblast activity, we conducted in vitro experiments using MC3T3-E1 cells and RAW264.7 cells. Our findings indicate that iron accumulation suppressed the activity of MC3T3-E1 while enhancing RAW264.7 function. Furthermore, iron overload significantly decreased oxidative stress levels; however, these detrimental effects can be mitigated by VIT treatment. Conclusion. Collectively, our data provide compelling evidence that VIT has the potential to reverse the deleterious consequences of iron overload on osseointegration and bone mass during ageing. Cite this article: Bone Joint Res 2024;13(9):427–440

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

Production of porous titanium bone implants is a highly promising research and application area due to providing high osseointegration and achieving the desired mechanical properties. Production of controlled porosity in titanium implants is possible with laser powder bed fusion (L- PBF) technology. The main topics of this presentation includes the L-PBF process parameter optimization to manufacture thin walls of porous titanium structures with almost full density and good mechanical properties as well as good dimensional accuracy. Moreover, the cleaning and coating process of these structures to further increase osseointegration and then in-vitro biocompatibility will be covered

We present the indications and outcomes of a series of custom 3D printed titanium acetabular implants used over a 9 year period at our institution (Sydney, Australia), in the setting of revision total hip arthroplasty. Individualised image-based case planning with additive manufacturing of pelvic components was combined with screw fixation and off-the-shelf femoral components to treat patients presenting with failed hip arthroplasty involving acetabular bone loss. Retrospective chart review was performed on the practices of three contributing surgeons, with an initial search by item number of the Medicare Benefits Scheme linked to a case list maintained by the manufacturer. An analysis of indications, patient demographics and clinical outcome was performed. The cohort comprised 65.2% female with a median age of 70 years (interquartile range 61–77) and a median follow up of 32.9 months (IQR 13.1 - 49.7). The indications for surgery were infection (12.5%); aseptic loosening (78.1%) and fracture (9.4%), with 65.7% of cases undergoing previous revision hip arthroplasty. A tumour prosthesis was implanted into the proximal femur in 21.9% of cases. Complications were observed in 31.3% of cases, with four cases requiring revision procedures and no deaths reported in this series. Kaplan-Meier analysis of all-cause revision revealed an overall procedure survival of 88.7% at two years (95%confidence interval 69 - 96.2) and 83.8% (95%CI 62 - 93.7) at five years, with pelvic implant-specific survival of 98% (95%CI 86.6 - 99.7) at two and five year follow up. We conclude that an individualised planning approach for custom 3D printed titanium acetabular implants can provide high overall and implant-specific survival at up to five years follow up in complex cases of failed hip arthroplasty and acetabular bone loss

Aim. Orthopedic implants play a tremendous role in fixing bone damages due to aging as well as fractures. However, these implants tend to get colonized by bacteria on the surface, leading to infections and subsequently prevention of healing and osteointegration. Recently, Roupie et al. showed that a nisin layer-by-layer based coating applied on biomaterials has both osteogenic and antibacterial properties. The Galleria mellonella larva is a well-known insect infection model that has been used to test the virulence of bacterial and fungal strains as well as for the high throughput screening of antimicrobial compounds against infections. Recently, we have developed an insect infection model with G. mellonella larvae to study implant-associated biofilm infections using Kirschner (K)-wires as implant material. Here, we would like to test the antibacterial capacity of nisin layer-by-layer based coatings on K-wires against Staphylococcus aureus in the G. mellonella larva implant infection model. Method. Prior to the implantation procedure, G. mellonella larvae are maintained at room temperature on wheat germ in an incubator. The larvae received bare titanium K-wires (uncoated), or either control-coated or nisin-coated K-wires. After one hour, the larvae were injected with 5×10. 5. S. aureus bacteria per larva (i.e., hematogenous implant infection model). Next, the larvae were incubated at 37. o. C in an incubator and the survival of the larvae was monitored for five days. Moreover, the number of bacteria on the implant surface and in the surrounding tissue was determined after 24h of incubation. Further, scanning electron microscopy (SEM) analyses were performed to study the effect of nisin on biofilm formation. Results. The larvae receiving the nisin-coated K-wires showed significantly higher survival rates compared to uncoated titanium K-wires, although not when compared to control-coated K-wires. A more than 1-log reduction in number of bacteria on the implant surface and in the surrounding tissue was observed in larvae receiving the nisin-coated K-wires, when compared to uncoated titanium K-wires SEM analysis showed reduced colonization of the bacteria nisin-coated K-wires compared to the controls. Conclusions. In conclusion, the antimicrobial nisin layer-by-layer based coating applied on titanium surfaces is able to prevent implant-related S. aureus biofilm infection in G. mellonella and is a promising antimicrobial strategy to prevent implant-related infections

We had previously reported on early outcomes on a new fluted, titanium, monobloc stem with a three degree taper that has been designed for challenging femoral reconstruction in the setting of extensive bone loss. The aim of this study was to report its mid-term clinical and radiographic outcomes. This is a retrospective review of prospectively collected data carried out at a single institution between Jan 2017 and Dec 2019. 85 femoral revisions were performed using a new tapered, fluted, titanium, monobloc (TFTM) revision stem. Complications, clinical and radiographic data were obtained from medical records and a locally maintained database. Clinical outcomes were assessed using the Oxford Hip Score (OHS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). All post-operative radiographs were analysed for subsidence, osteolysis and femoral cortical bone remodelling. Mean follow-up was 60 months (range 28–84 months). Subsidence of 1.2 mm was noted in one patient. No cases of clinically significant subsidence (10 mm) were observed. At final follow-up, a statistically significant improvement was noted in functional outcome scores. The mean OHS preoperatively and at final follow-up were 24 (SD 13) and 42 (SD15). p = 0.04 mean difference 18 (95% CI 15–22). The mean WOMAC scores preoperatively and at final follow-up were 62 (SD23) and 88 (SD7) respectively (p < 0.001, mean difference 26; 95% CI 21–34). No stem fractures were noted within the follow-up period. Two patients had revision of the stem's one for infection and another for persistent pain. Positive mid-term clinical and radiological outcomes have been observed with this tapered, fluted, titanium, monobloc stem. Based on these results, this implant may be considered as a viable option in the majority of uncemented femoral revisions

In primary total hip arthroplasty (THA) for patients with Crowe II or higher classes developmental dysplasia of the hip (DDH) or rapidly destructive coxopathy (RDC), the placement of the cup can be challenging due to superior and lateral acetabular bone defects. Traditionally, bone grafts from resected femoral heads were used to fill these defects, but bulk graft poses a risk of collapse, especially in DDH with hypoplastic femoral heads or in RDC where good quality bone is scarce. Recently, porous metal augments have shown promising outcomes in revision surgeries, yet reports on their efficacy in primary THA are limited. This study retrospectively evaluated 27 patients (30 hips) who underwent primary THA using cementless cups and porous titanium acetabular augments for DDH or RDC, with follow-up periods ranging from 2 to 10 years (average 4.1 years). The cohort included 22 females (24 hips) and 5 males (6 hips), with an average age of 67 years at the time of surgery. The findings at the final follow-up showed no radiographic evidence of loosening or radiolucency around the cups and augments, indicating successful biological fixation in all cases. Clinically, there was a significant improvement in the WOMAC score from an average of 39.1±14.7 preoperatively to 5.1±6.4 postoperatively. These results suggest that the use of cementless cups and porous titanium acetabular augments in primary THA for DDH and RDC can lead to high levels of clinical improvement and reliable biological fixation, indicating their potential as a viable solution for managing challenging acetabular defects in these conditions

The aim of this study is to compare the release of titanium (Ti) and zirconium (Zr) into the tissue surrounding Ti- and ZrO. 2. -implants. Methyl methacrylate embedded mini pig maxillae with 6 Ti-implants and 4 ZrO2-implants were analysed after 12-weeks of implantation. The spatial distribution of elemental Ti and Zr in maxillae near implants was assessed with laser ablation (LA)-inductively coupled plasma (ICP)-mass spectrometry (MS). From each maxilla two bone slices adjacent to the implants were measured. The contents of Ti and Zr in these bone slices were determined by ICP-MS and ICP-optical emission spectrometry. Increased intensity of Ti and Zr could be detected in bone tissues at a distance of 891±398 µm (mean ± SD) from Ti-implants and 927±404 µm from ZrO2-implants. The increased intensity was mainly detected near implant screw threads. The average Ti content detected in 11 bone slices from samples with Ti-implants was 1.67 mg/kg, which is significantly higher than the Ti content detected in 8 slices from samples with ZrO. 2. -implants. The highest Ti content detected was 2.17 mg/kg. The average Zr content in 4 bone slices from samples with ZrO. 2. -implants is 0.59 mg/Kg, the other 4 bone slices showed Zr contents below the detection limit (. After 12-weeks of implantation, increased intensity of Ti and Zr can be detected in bone tissues near Ti- and ZrO. 2. -implants. The results show that Ti content released from Ti-implants is higher than the Zr content released from ZrO. 2. -implants

Numerous implanted hip and knee joint arthroplasties have to be replaced due to early or late loosening of the implant, a failure of osteointegration with fibrous tissue at the bone-implant-interface. This could be counteracted by ensuring that cells which attach to the implant surface differentiate towards bone cells afterwards. For this reason, human mesenchymal stem cells (hMSCs) will be included in this study. These cells are naturally available at the bone-implant-interface, multipotent and therefore ideal to study the osteoinductivity of a material. The goal of this pilot study was to test the cell response towards three different titanium grades with a novel surface structuring, as a first step towards achieving an improved implant surface for enhanced osteointegration. Disk-shaped titanium scaffolds with a diameter of 12 mm and a height of 1.2 mm were used. The surface topography (500 µm × 500 µm × 300 µm pores) was generated via laser treatment of the surface. By using nanosecond pulsed laser technique, a rough surface with micro- and nanostructural (titanium droplets) features was automatically formed. Three different batches made of commercially pure titanium grades 1 and 2 (Ti1/Ti2) or Ti6Al4V alloy grade 5 (Ti5) were produced. Four cell types were analysed on these batches: primary hMSCs from one donor (m, 25 y), periosteum derived cells (PDCs), human osteoblasts (hOBs) and periodontal ligament cells (PDLs). Cells were seeded on Ti1, Ti2 and Ti5 scaffolds in triplicates. Resazurin assay to examine cell viability was conducted with all cell types. Measurements were executed on several days after seeding, from day one up to day 14. Actin staining as well as live/dead staining was performed with hMSCs cultured on titanium for 1, 3, 5 or 7 days. The cell viability assay revealed early turning points of growth for osteogenic hOBs (day 3) and PDCs (day 7). HMSCs grew steadily on the material and non-osteogenic PDLs stayed in plateau throughout the cultivation period. With respect to the material, cells demonstrated better proliferation on Ti1 and Ti2 than on Ti5. Live/dead staining showed a high survival rate of hMSCs at each time point and on all three titanium grades, with a neglectable number of dead cells. Actin staining confirmed an enhanced spreading and stretching of hMSCs on Ti1 and Ti2 compared to hMSCs on Ti5. Our pilot data indicates that cells react to different titanium compositions, revealed by increased proliferation on commercially pure titanium (Ti1/2). Furthermore, our results demonstrate that osteogenic cells prefer the novel surface structuring in comparison to non-osteogenic PDL cells, which stayed in plateau. The turning points of growth (hOBs/PDCs) suggest an osteosupportiveness of the surface. Although hMSCs did not show a turning point in growth, their growth was steady and resulted in the highest number of cells along with a well stretched morphology. Due to their good proliferation and response to the material, hMSCs are currently being used for evaluating the osteogenic potential of the novel scaffolds

The use of implant biomaterials for prosthetic reconstructive surgery and osteosynthesis is consolidated in the orthopaedic field, improving the quality of life of patients and allowing for healthy and better ageing. However, there is the lack of advanced innovative methods to investigate the potentialities of smart biomaterials, particularly for the study of local effects of implant and osteointegration. Despite the complex process of osseointegration is difficult to recreate in vitro, the growing challenges in developing alternative models require to set-up and validate new approaches. Aim of the present study is to evaluate an advanced in vitro tissue culture model of osteointegration of titanium implants in human trabecular bone. Cubic samples (1.5×1.5 cm) of trabecular bone were harvested as waste material from hip arthroplasty surgery (CE AVEC 829/2019/Sper/IOR); cylindrical defects (2 mm Ø, 6 mm length) were created, and tissue specimens assigned to the following groups: 1) empty defects- CTR-; 2) defects implanted with a cytotoxic copper pin (Merck cod. 326429)- CTR+; 3) defects implanted with standard titanium pins of 6 µm-rough (ZARE S.r.l) -Ti6. Tissue specimens were cultured in mini rotating bioreactors in standard conditions, weekly assessing viability. At the 8-week-timepoint, immunoenzymatic, microtomographic, histological and histomorphometric analyses were performed. The model was able to simulate the effects of implantation of the materials, showing a drop in viability in CTR+, differently from Ti6 which appears to have a trophic effect on the bone. MicroCT and histological analysis supported the results, with lower BV/TV and Tb.Th values observed in CTR- compared to CTR+ and Ti6 and signs of matrix and bone deposition at the implant site. The collected data suggest the reliability of the tested model which can recreate the osseointegration process in vitro and can therefore be used for preliminary evaluations to reduce and refine in vivo preclinical models. Acknowledgment: This work was supported by Emilia-Romagna Region for the project “Sviluppo di modelli biologici in vitro ed in silico per la valutazione e predizione dell'osteointegrazione di dispositivi medici da impianto nel tessuto osseo”

Polyetheretherketone (PEEK) interbody fusion cages combined with autologous bone graft is the current clinical gold standard treatment for spinal fusion, however, bone graft harvest increases surgical time, risk of infection and chronic pain. We describe novel low-stiffness 3D Printed titanium interbody cages without autologous bone graft and assessed their biological performance in a pre-clinical in vivo interbody fusion model in comparison to the gold standard, PEEK with graft. Titanium interbody spacers were 3D Printed with a microporous (Ti1: <1000μm) and macroporous (Ti2: >1000μm) design. Both Ti1 and Ti2 had an identical elastic modulus (stiffness), and were similar to the elastic modulus of PEEK. Interbody fusion was performed on L2-L3 and L4-L5 vertebral levels in 24 skeletally mature sheep using Ti1 or Ti2 spacers, or a PEEK spacer filled with iliac crest autograft, and assessed at 8 and 16 weeks. We quantitatively assessed bone fusion, bone area, mineral apposition rate and bone formation rate. Functional spinal units were biomechanically tested to analyse range of motion, neutral zone, and stiffness. Results: Bone formation in macroporous Ti2 was significantly greater than microporous Ti1 treatments (p=.006). Fusion scores for Ti2 and PEEK demonstrated greater rates of bone formation from 8 to 16 weeks, with bridging rates of 100% for Ti2 at 16 weeks compared to just 88% for PEEK and 50% for Ti1. Biomechanical outcomes significantly improved at 16 versus 8 weeks, with no significant differences between Ti and PEEK with graft. This study demonstrated that macroporous 3D Printed Ti spacers are able to achieve fixation and arthrodesis with complete bone fusion by 16 weeks without the need for bone graft. These significant data indicate that low-modulus 3D Printed titanium interbody cages have similar performance to autograft-filled PEEK, and could be reliably used in spinal fusion avoiding the complications of bone graft harvesting

Aims. Metal particles detached from metal-on-metal hip prostheses (MoM-THA) have been shown to cause inflammation and destruction of tissues. To further explore this, we investigated the histopathology (aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) score) and metal concentrations of the periprosthetic tissues obtained from patients who underwent revision knee arthroplasty. We also aimed to investigate whether accumulated metal debris was associated with ALVAL-type reactions in the synovium. Methods. Periprosthetic metal concentrations in the synovia and histopathological samples were analyzed from 230 patients from our institution from October 2016 to December 2019. An ordinal regression model was calculated to investigate the effect of the accumulated metals on the histopathological reaction of the synovia. Results. Median metal concentrations were as follows: cobalt: 0.69 μg/g (interquartile range (IQR) 0.10 to 6.10); chromium: 1.1 μg/g (IQR 0.27 to 4.10); and titanium: 1.6 μg/g (IQR 0.90 to 4.07). Moderate ALVAL scores were found in 30% (n = 39) of the revised knees. There were ten patients with an ALVAL score of 6 or more who were revised for suspected periprosthetic joint infection (PJI), aseptic loosening, or osteolysis. R2 varied between 0.269 and 0.369 for the ordinal regression models. The most important variables were model type, indication for revision, and cobalt and chromium in the ordinal regression models. Conclusion. We found that metal particles released from the knee prosthesis can accumulate in the periprosthetic tissues. Several patients revised for suspected culture-negative PJI had features of an ALVAL reaction, which is a novel finding. Therefore, ALVAL-type reactions can also be found around knee prostheses, but they are mostly mild and less common than those found around metal-on-metal prostheses. Cite this article: Bone Joint Res 2024;13(4):149–156

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