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

INTRODUCTION. Additive manufacturing (3D printing) is used to create porous surfaces that promote bone ingrowth in an effort to improve initial stability and optimize long-term biological fixation. The acetabular cup that was studied is manufactured with titanium alloy powder via electron beam melting. Electron beam melting integrates the porous and solid substrate rather than sintering a porous coating to a solid surface. The 3D-printed acetabular cup's high surface coefficient of friction (up to 1.2), combined with its geometry, creates a predictable press-fit in the acetabulum, improving initial mechanical stability and ultimately leading to reproducible biologic fixation. The objective of this study was to evaluate the early clinical outcomes and implant fixation of this 3D-printed acetabular cup in total hip arthroplasty (THA). METHODS. Four hundred twenty-eight subjects from 8 US and international research sites underwent primary THA with the 3D-printed acetabular cup. All sites received IRB approval prior to conducting the study, and all participants signed the informed consent. Screw usage and number used during surgery were used as a surrogate measurement for initial implant fixation. Clinical performance outcomes included pre- and post-operative Harris Hip Scores (HHS) and Oxford Hip Scores (OHS), patient satisfaction, and revision assessment. 215 patients had a minimum 1-year post-operative follow-up visit. Student t-tests were used to identify significant mean differences (p<0.05). RESULTS. Acetabular screws were used in 206 of 428 cases (48.1%); 85.9% used 1 screw, 12.6% used 2 screws, and 1.5% used 3 screws. For patients with a 1-year post-operative visit, the HHS improved by 49.8 points to 91.9 from 42.1, and the OHS improved by 27.7 points to 44.4 from16.7. Patient satisfaction scores at the 1-year post-operative visit were 9.7±0.7 (n=94). There was no significant difference between genders with regard to BMI, the 1-year post-operative HHS, OHS, or patient satisfaction scores. However, the males were significantly younger (59.8 vs. 62.9 years) and had significantly higher pre-operative HHS (45.7 vs. 37.9) and OHS scores (17.8 vs. 15.3). There were 9 revisions reported. DISCUSSION. For initial implant fixation, compared to a similar, non-3D-printed acetabular cup in the same product line, the 3D-printed cup used significantly fewer screws per case (n=1 for 85.9% cases vs. n=2 for 85.7% of cases) in a fewer percentage of cases (48.1% vs. 70.4%), suggesting greater initial stability and “scratch fit”. The 3D-printed acetabular cup also displayed positive early clinical results as evidenced by the pronounced improvement in clinical outcome scores from the pre-operative visit to the 1-year post-operative visit. These 1-year improvements are better than moderate clinically important improvements reported in the literature (40.1 points for HHS). Patient satisfaction scores were also excellent (9.7/10). There were nine revisions; however, four of these were due to patient falls and one was due to infection. SIGNIFICANCE. The 3D-printed acetabular cup evaluated in this study demonstrated improved implant fixation and positive early clinical outcomes for THA

Introduction. Trabecular Titanium is a biomaterial characterized by a regular three-dimensional hexagonal cell structure imitating trabecular bone morphology. Components are built via Electron Beam Melting technology in aone- step additive manufacturing process. This biomaterial combines the proven mechanical properties of Titanium with the elastic modulus provided by its cellular solid structure (Regis 2015 MRS Bulletin). Several in vitro studies reported promising outcomes on its osteoinductive and osteoconductive properties: Trabecular Titanium showed to significantly affect osteoblast attachment and proliferation while inhibiting osteoclastogenesis (Gastaldi 2010 J Biomed Mater Res A, Sollazzo 2011 ISRN Mater Sci); human adipose stem cells were able to adhere, proliferate and differentiate into an osteoblast-like phenotype in absence of osteogenic factors (Benazzo 2014 J Biomed Mater Res A). Furthermore, in vivo histological and histomorphometric analysis in a sheep model indicated that it provided bone in-growth in cancellous (+68%) and cortical bone (+87%) (Devine 2012 JBJS). A multicentre prospective study was performed to assess mid-term outcomes of acetabular cups in Trabecular Titanium after Total Hip Arthroplasty (THA). Methods. 89 patients (91 hips) underwent primary cementless THA. There were 46 (52%) men and 43 (48%) women, with a median (IQR) age and BMI of 67 (57–70) years and 26 (24–29) kg/m2, respectively. Diagnosis was mostly primary osteoarthritis in 80 (88%) cases. Radiographic and clinical evaluations (Harris Hip Score [HHS], SF-36) were performed preoperatively and at 7 days, 3, 6, 12, 24 and 60 months. Bone Mineral Density (BMD) was determined by dual-emission X-ray absorptiometry (DEXA) according to DeLee &Charnley 3 Regions of Interest (ROI) postoperatively at the same time-points using as baseline the measureat 1 week. Statistical analysis was carried out using Wilcoxon test. Results. Median (IQR) HHS and SF-36 improved significantly from 48 (39–61) and 49 (37–62) preoperatively to 99 (96–100) and 76 (60–85) at 60 mo. (p≤0.0001). Radiographic analysis showed evident signs of bone remodelling and biological fixation, with presence of superolateral and inferomedial bone buttress, and radial trabeculae in ROI I/II. All cups resulted radiographically stable without any radiolucent lines. The macro-porous structure of this biomaterial generates a high coefficient of friction (Marin 2012 Hip Int), promoting a firm mechanical interlocking at the implant-bone interface which could be already observed in the operating room. BMD initially declined from baseline at 7 days to 6 months. Then, BMD slightly increased or stabilized in all ROIs up to 24 months, while showing evidence of partial decline over time with increasing patient' age at 60 months, although without any clinical significance in terms of patients health status or implant stability. Statistical significant correlations in terms of bone remodeling were observed between groups of patients on the basis of gender and age (p≤0.05). No revision or implant failure was reported. Conclusions. All patients reported significant improvements in quality of life, pain relief and functional recovery. Radiographic evaluation confirmed good implant stability at 60 months. These outcomes corroborate the evidence reported on these cups by orthopaedic registries and literature (Perticarini 2015 BMC Musculoskelet Disord; Bistolfi 2014 Min Ortop)

INTRODUCTION. Trabecular Titanium is an open-cell regular structure composed by hexagonal cells of controlled pore, manufactured by Electron Beam Melting (EBM) technology, that allows moulding of cellular solid structures. The Lima Delta TT revision cups are One and Revision, which is characterized by a caudal hook and fins. Both allow internal modularity and cranial TT augments. The aim of this prospective study is to evaluate the short to medium-term clinical and radiographic outcomes of acetabular revision cups in TT. METHODS. Between December 2008 and March 2013 we performed 60 cup revisions, 33 with the Revision cup and 27 with the One cup. The bone defect was classified according to Paprosky acetabular classification: type IIb and IIc presenting continent anterior and posterior acetabular wall were treated by Delta One TT; type IIIa and IIIb were treated with Delta TT Revision. In 20 cases (3.3%) stem revision was associated. Causes of revision were: aseptic loosening in 48 cases, periprosthetic acetabular fractures in 5 cases, recurrent dislocation in 5 cases, infection in 2 cases. In 52 cases bone grafts were used to fill cavitary defects (AIR 1–4). Hemispheric TT augments were used in 13 cases with the same aim. Internal modules were used in 39 cases to restore correct offset. The mean age of patients was 69.6 years (range 29–90). The average follow-up was 39 months (range 19–70). RESULTS. Mean Harris Hip Score (HHS) was 39.9 preoperatively and 82.7 at last follow-up. We had no intraoperative complications. We had 2 cases of superficial infection, one of which required revision of the surgical wound. 4 patients suffered dislocation episodes (1 recurrent); none of them required revision. We had 1 case of asymptomatic aseptic loosening, which did not require intervention. In the remaining cases no radiographic evidence of radiolucent lines was noticed at follow up, neither any evidence of aseptic loosening. The graft was considered to be integrated in all cases. DISCUSSION AND CONCLUSION. Trabecular Titanium revision cups showed high capacity of osseointegration, providing good results in short to medium-term follow-up. Further studies are necessary to assess long-term survivorship

Rapid manufacturing using laser beam and/or electron beam has been applied to fabrication of artificial hip and knee joints in quite recent years. In the electron beam melting (EBM) method, the high energy electron beam effectively melts the metal powder without creating flaws such as porosities or inclusions of oxide particles during building. Thus it is found that EBM technique for rapid manufacturing of artificial hip and knee joints processes a higher possibility as the next-generation methodology for fabrication of the medical devices such as hip and knee joints. In the present study, we focus on the EBM technique. The microstructures and mechanical properties of Co-29Cr-6Mo alloy with C and N additions, produced by using EBM method, were studied using X-ray diffraction, electron back scatter diffraction, transmission electron microscope (TEM), Vickers hardness tests, and tensile tests, focusing on the influences on the build direction and the various heat treatments after build. It is found that the microstructures for the as built specimens were changed from columnar (Fig. 1a) to eqiaxed grain structure (Fig. 1c) with average grain size of approximately 10–20 μm due to the heat treatment employing the reverse transformation from a lamellar (hcp + Cr. 2. N) phase to an fcc phase. Our results will contribute to the development of biomedical Ni-free Co–Cr–Mo–N-C alloys, produced by EBM method, with refined grain size and good mechanical properties, without requiring any hot workings. Fig. 1 Inverse pole figure (IPF) maps of microstructure of samples produced by EBM method, taken by EBSD. (a) as-built, (b) after aging treatment, (c) after reverse transformation heat treatment (RT-HT)

Summary. Osseointegrated Amputation Prostheses can be functionalised by both biological augmentation and structural augmentation. These augmentation techniques may aid the formation of a stable skin-implant interface. Introduction. Current clinical options are limited in restoring function to amputees, and are associated with contact dermatitis and infection at the stump-socket interface. Osseointegrated Amputation Prosthesis attempts to solve issues at the stump-socket interface by directly transferring axial load to the prosthesis, via a skin-penetrating abutment. However, development is needed to achieve a seal at the skin-implant interface to limit infection. Fibronectin, an Extracellular Matrix protein, binds to integrins during wound healing, with the RGD tripeptide being part of the recognition sequence for its integrin binding domain. In vitro work has found silanization of RGD to polished titanium discs up regulates fibroblast attachment compared to polished control. Electron Beam Melting can produce porous titanium alloy implants, which may encourage tissue attachment. This study aims to test whether a combination of biological RGD coatings and porous metal manufacturing techniques can encourage the formation of a seal at the skin-implant interface. Materials and Methods. We developed four different augmented transcutaneous devices: Porous, Porous RGD coated, drilled and drilled RGD coated. These were implanted in tibial transcutaneous ovine model, n=6, for a period of 6 months. Following explantation we performed hard grade resin histology to assess soft tissue attachment at the transcutaneous interface. Results. Histological analysis revealed no statistical difference in epithelial downgrowth and epidermal attachment values between the four augmented devices. There were significant increases (p<0.05) in the number of blood vessels and the number of cells in the Porous RGD devices compared with both drilled implant devices. Both Porous and Porous RGD implant groups observed significant increase (p<0.05) in soft tissue infiltration compared with both Drilled implant devices. Discussion. The use of porous structures and RGD coatings increases tissue ingrowth and revascularisation in ITAP devices despite having no effect on epithelial downgrowth and epidermal attachment in a long-term ovine model. There were no detrimental effects in the transcutaneous interface formation observed. These augmentation techniques may prove beneficial in preclinical and clinical developments of transcutaneous osseointegrated devices

Introduction. Successful cementless acetabular designs require sufficient initial stability between implant and bone (with interfacial motions <150 μm) and close opposition between the porous coating and the reamed bony surface of the acetabulum to obtaining bone ingrowth and secondary stability. While prior generations of cementless components showed good clinical results for long term fixation, modern designs continue to trend toward increased porosity and improved frictional characteristics to further enhance cup stability. Objectives. We intend to experimentally assess the differences in initial stability between a hemispherical acetabular component with a highly porous trabecular tantalum fixation surface (Continuum. ®. Acetabular System, Zimmer Inc, Warsaw, IN)(Fig 1) and a hemispherical component with the new highly porous Trabecular Titanium. ®. surface (Delta TT, Lima Corporate, Italy)(Fig 2) manufactured by electron beam melting. Material and methods. A total of 16 cups were used, 8 for each type. Each cup was used 4 times. Cups were implanted in polyurethane foam blocks with 1mm interference fit and subsequently edge loaded to failure. Two different foam block densities (0.24 g/cm. 3. and 0.32g/cm. 3. ) were used to model low- and high-density bone stock. Each cup was seated into a block under displacement control using a servohydraulic test machine (MTS Bionix 858, Eden Praire, MN) to engage the locking mechanism until axial forces reach 8 to 10 kN. During insertion, force and displacement were recorded to determine the implantation force for each component. After seating, initial acetabular component fixation was assessed using an edge loading test. Descriptive statistics are presented as means and standard deviations for continuous variables. The Kruskal-Wallis test was used to assess the effect of Cup on the outcomes: (1) Insertion force, (2) Insertion energy, (3) Ultimate load, (4) Yield load, and (5) Ultimate Energy. Pairwise comparisons were done using Mann-Whitney U test for significant outcomes and multiple comparisons were adjusted using Bonferroni correction. All analyses were performed with SAS version 9.3 (SAS Institute, Inc., Cary, NC, USA); a p-value less than 0.05 was considered statistically significant. Results. Delta TT cup required the same seating force (p=0.014) and 18% higher insertion energy (p=0.002) for fully seating compared to Continuum cup, however this difference is not clinically relevant. Delta TT cup exibithed more stability, as exibithed by significantly higher (35%) energy to ultimate load (p=0.014). No statistical differences were found in Ultimate load and Yield load among the 2 cups. Cups in higher density foam required higher force and energy to be seated. In edge load testing higher densities blocks generated higher force and energy accross all cup designs. Conclusions. The result of this study indicate increased interface stability in Trabecular Titanium cup compared to Porous tantalum cup with a low incresing in the energy required for fully seating

INTRODUCTION. Managing severe periacetabular bone loss during revision total hip arthroplasty (THA) is a challenging task. Multiple treatment options have been described. Delta Revision Trabecular Titanium™ (TT) cup is manufactured by Electron Beam Melting (EBM) technology that allows modulating cellular solid structures with an highly porous structure were conceived to rich the goals of high bone ingrowth and physiological load transfer. The caudal hook and fins ensure additional stability and the modular system allows the surgeon to treat bone defects in the most complex revisions. Entirely modular, the system can meet all intra-operative needs thanks to a customized implant construction. The aim of this prospective study is to evaluate the short to mid-term clinical and radiographic outcomes of this acetabular revision cups. MATERIALS AND METHODS. We prospectively assessed clinical and radiographic results of 31 cases of acetabular revisions that were performed from June 2007 and March 2012 by Delta TT Lima Revision system. The mean age of patients was 69.5 years (range 29–90). The causes of revision were aseptic loosening in 22 cases (71.0%), periprosthetic acetabular fractures in 4 cases (13.0%), multiple dislocation of the primary implant in 3 cases (9.6%) and outcome of infection in 2 cases (6.4%). Stem revision was performed in 11 cases (35,4%). In 24 cases bone impaction grafting was used to fill cavitary defects (Paprosky 2B-3A); in 7 cases TT augments were used with the same aim. The average follow-up was 32 months (range 12–69). RESULTS AND CONCLUSIONS. No major complications were observed. The mean HHS significantly increased from 39.9 (range 17–60) preoperatively to 86.5 (range 65–100) at the last follow-up examination. The implanted cups were radiographically stable at the last follow-up visit without radiolucent lines or periprosthetic osteolysis. Trabecular Titanium showed a high capacity of osseointegration, providing excellent results in short to mid-term follow-up. The impaction grafting has demonstrated effective restoration of bone stock and no radiographic evidence bone resorption (Fig. 1). DISCUSSION. Delta Revision TT is a good solution for acetabular revision surgery even when there are cavitary and segmental bone defects. It is possible to restore muscle tension and correct anatomical impairments, while enhancing implant stability and minimising the risk of dislocation

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