Background: Glenoid loosening is a well-documented failure mechanism in anatomic shoulder arthroplasty. Implant manufacturers have developed innovative designs to address these issues, with hybrid glenoid components emerging as a potential solution. This study investigates the Exactech Equinoxe glenoid (Exactech Inc., Gainesville, FL, USA), a hybrid component that has shown higher midterm revision rates in national registry data. Methods: We conducted an investigation of failed Equinoxe Cage Glenoid implants revised between November 2022 and July 2025 and analyzed at a tertiary arthroplasty retrieval center. Clinical data, radiographs, and intraoperative findings were reviewed. Radiographs were assessed for radiolucency (Lazarus score), implant position, and evidence of fracture or metallic debris. Retrieved components underwent macroscopic inspection and evaluation of wear modes. Polyethylene (PE) oxidation was quantified through white-banding assessment and Fourier Transform Infrared Spectroscopy. Periprosthetic tissues, when available, underwent inductively coupled plasma mass spectrometry to evaluate metal ion presence. Results: Eleven failed hybrid glenoid components were analyzed at a median of 5.8 years after implantation. Radiographic loosening was present in 82% of cases (median Lazarus score 5). All retrieved components demonstrated macroscopic PE wear; 82% showed cracking and delamination. Fourier Transform Infrared Spectroscopy confirmed subsurface oxidation in all tested components. Peripheral peg fixation was limited, with 100% of pegs demonstrating minimal bony ongrowth and 45% showing polishing consistent with micro-motion. In contrast, 100% of central metal cages exhibited bony ingrowth. Metal debris or staining was noted in 55% of cases, and tissue samples demonstrated elevated metal ions consistent with cage or peg wear. Conclusion: Failed Equinoxe Cage Glenoid implants demonstrated consistent patterns of PE oxidation and inadequate peripheral peg fixation, contributing to loosening and mechanical failure at the PE-metal interface. These findings provide a potential mechanism for the higher revision rate observed in national registry data and highlight the importance of ongoing postmarket surveillance of new implant designs.

BACKGROUND:This study aimed to determine whether femoro-tibial component size mismatch in a fixed-bearing total knee arthroplasty (TKA) design is associated with increased polyethylene (PE) wear. We hypothesized that mismatched knees, particularly those with a femur greater than the tibia, would demonstrate higher PE wear. METHODS:A retrospective retrieval analysis was performed on a fixed-bearing design revised between 2008 and 2024. Implants were categorized as matched (femur = tibia), femur (F) greater than tibia (T), or femur less than tibia. A total of 105 implants were included. The PE inserts were graded using the modified Hood scoring system. Mixed-effects models evaluated associations between mismatch and wear severity across regions and surfaces, and Cox regression analyzed time in situ. RESULTS:Total PE wear did not differ between groups (mean matched 47.6 ± 23.6; F greater than T, 46.1 ± 22.6; F less than, T 51.3 ± 19.4; P = 0.81; Cohen's d < 0.20). In multilevel modeling, mismatch was not associated with overall wear (Wald Chi-square 0.42; P = 0.81). A significant surface × mismatch interaction was identified (P < 0.001): F greater than T knees exhibited greater backside wear compared with matched (P = 0.021; d approximately 0.37), but there was no increase in bearing-surface wear (P = 0.24). Time in situ (P < 0.001) and older age (P = 0.014) were the only independent predictors of wear. Burnishing, scratching, and pitting were the dominant wear mechanisms. Mismatch did not affect implant survival, with no difference in time in situ (Cox P = 0.456). CONCLUSIONS:Femoro-tibial size mismatch did not result in greater total or bearing-surface PE wear. The modest increase in backside wear observed in F greater than T did not translate into reduced survivorship. These findings suggest that the higher revision risk reported in mismatched TKAs may involve mechanisms beyond PE wear alone.

Aims:This study reports the outcome of a modern total knee arthroplasty design using a cementless tibial baseplate compared to the full-cemented version. Methods:Consecutive cohorts with 12-month follow-up were evaluated. Patients receiving a cementless tibial baseplate were compared to those who received a cemented tibial component. Endpoints included revision rates and reason for revision, patient-reported outcome measures (PROMs) using the Oxford Knee Score (OKS), and progressive radiolucency. Retrieval analysis was performed for the revised cases. Pearson correlation analysis and multiple regression analysis were used. Results:A total of nine knees (7%) from the cementless cohort were revised, all due to aseptic loosened baseplate at a mean follow-up of 10.4 months (3 to 19), whereas the incidence of aseptic loosening of the cemented tibial baseplate was significantly lower at 0.5% (3/534; p < 0.001). The cemented cohort PROMs outperformed the cementless baseplate group at both 12 months' follow-up and the improvement from baseline (mean OKS 40.4 (SD 6.8) vs 38.5 (SD 8.1); p = 0.006; mean ΔOKS 18.8 (SD 9.0) vs 15.5 (SD 12.8); p < 0.001). There were no significant differences between the groups in the occurrence of new radiolucency at 12 months (p = 0.325). An elevated BMI was the only factor to correlate (r = -0.195) with worse values of ΔOKS (p = 0.048) in the cementless cohort. The multiple regression analysis determined that an increased BMI was the single independent predictor for aseptic loosening (p = 0.024) for the knees with a cementless tibial baseplate. Retrieval analysis suggested failed osseointegration. Conclusion:In our cohort, there was a significantly higher incidence of aseptic loosening and worse PROMs at one year for the cementless tibial baseplate. An increased BMI may be an independent risk factor for aseptic loosening and inferior PROMs.

The generation of wear debris from orthopedic implants is a known cause of implant failure, particularly in joint replacements. While much research has focused on wear particles from knee and hip implants, spinal implants, such as total disc replacements (TDRs), have received less attention despite their increasing clinical use. Spinal implants face unique biomechanical challenges, including a wider range of motion and higher loads, leading to complex tissue interactions. Studies reveal that TDR wear particles, though similar in size to those from knee implants, cause a stronger immune response, with more macrophages and giant cells found in the surrounding tissue. This may explain the high revision rates seen in spinal surgeries, with some interventions failing in over 30% of cases within 10 years. The younger population undergoing spinal surgery, combined with the productivity losses associated with implant failure, underscores the need for greater understanding. This review discusses recent research on the generation, characterization, and biological impacts of spinal implant wear debris. It draws on retrieval analysis, wear simulation, in vivo models, and a survey conducted with the AO Spine Knowledge Forum Degenerative to assess current clinical practices and highlight gaps in knowledge. Additionally, this critical review explores future strategies to reduce the biological impact of wear particles and improve the safety and longevity of spinal implants through better therapeutics and design innovations. By combining literature and clinical insights, this paper aims to guide future research in addressing the complexities of spinal implant wear and its biological consequences.

Early tibial loosening has been reported in the Attune total knee arthroplasty (TKA) system, with uncertainty regarding the contribution of clinical, demographic, and implant-related factors. We retrospectively analyzed 130 retrieved Attune TKAs from 126 patients across nine institutions. Clinical and demographic data, reasons for revision, and implant features were collected. Cement coverage of 96 cemented tibial baseplates was quantified using digitized image analysis, and 15 polyethylene tibial bearings underwent mechanical and oxidation testing. Statistical significance was defined as p < 0.05. The mean time in situ was 2.0 years (range 0.1–8.3). Main reasons for revision were loosening (37.7

Background: Dual mobility (DM) implants in total hip arthroplasty provide excellent range of motion with low dislocation rates. A complication of this design is intraprosthetic dislocation (IPD), where the polyethylene (PE) liner dissociates from the femoral head. In older designs, IPD occurred due to a small head size and late PE wear with head-capture-mechanism failure. Routine retrieval analysis identified concerns regarding IPD of modern implants, and scant reporting in the literature led to this retrospective study. Methods: A total of 124 (110 primary, 14 revision) DM implants (mean in situ time 2.0 ± 3.1 years) revised by 20 surgeons across Western Australia between July 2014 and August 2023 were assessed. Demographics, clinical information, mechanisms of failure, and observations at revision arthroplasty were analyzed. The retrieval analysis included an assessment of metal and PE wear mechanisms, corrosion between modular components, and extent of bony attachment to acetabular shells. Results: There were 11 cases of IPD. Of these, 8 (73%) had a documented preceding failed closed reduction, with the remaining 3 revised due to trunnionosis, loosening, and joint instability. Nine out of 11 (82%) cases were female. Although metallic wear and inner-lip impingement of PE bearings were observed, there was no obvious failure mechanism for the other 3 retrieved IPD implants. Conclusions: Most cases of IPD in DM implants occur after failed closed reduction in the setting of a hip dislocation, suggesting an iatrogenic cause of IPD. No implant-related features could be defined for the remaining cases. Recognizing common failure modes can help with the prevention and treatment of this complication.

Introduction A recent study reported a 34% mid-term revision rate after M6-C™ cervical total disc replacement (CTDR) for wear-related osteolysis. Here, we aim to investigate the prevalence, risk factors, and radiographic characteristics of periprosthetic bony changes and implant failure of the M6-C™ artificial disc. Methods We retrospectively analysed radiographic (conventional X-ray, CT scan) and clinical outcomes (EQ-5D-5L, Neck Disability Index (NDI), and Visual Analog Scale (VAS) for neck and arm pain) data collected during routine follow-up of patients who underwent CTDR with the M6-C™ between 2011 and 2015. Results In total, 85 patients underwent CTDR with the M6-C™. Follow-up data were available for 43 patients (54% female, mean age 44 years) with 50 implants and a mean follow-up of 8.1 years (6.5–11 years). Implant failure with the presence of severe osteolysis was identified in 5 (12%) patients who were all male ( p = 0.016) and implanted at the C5/6 level ( p = 0.11). All failed implants required revision surgery. The overall prevalence of osteolysis was 44% (22/50 implants) and 34% (17/50 implants) for significant heterotopic ossification. Patients with high-grade osteolysis showed higher VAS arm pain ( p = 0.05) and lower EQ-5D-VAS health VAS ( p = 0.03). Conclusion We report a lower reoperation rate for failed M6-C™ implants than previously published, but confirmed that osteolysis and heterotopic ossification are common following CTDR with the M6-C™ and may be asymptomatic. Therefore, we strongly recommend ongoing clinical and radiographic monitoring after CTDR with the M6-C™, particularly for male patients implanted at the C5/6 level.

ObjectivesSeveral studies have reported elevated blood cobalt (Co) and chromium (Cr) concentrations in patients with total knee replacements (TKRs). Up to 44% of tissue samples taken from patients with failed TKRs exhibit histological evidence of metal sensitivity/ALVAL. In simulated conditions, metal particles contribute approximately 12% of total wear debris in TKR. We carried out this investigation to determine the source and quantity of metal release in TKRs.Design and MethodsWe analysed 225 explanted fixed-bearing TKRs (Attune, Genesis II, NexGen, PFC, and Vanguard) revised for any indication. These were analysed using peer-reviewed [coordinate measuring machine (CMM)] methodology to measure the volumetric wear of the polyethylene (PE) bearing surfaces and trays. The trays were analysed using 2D profilometry (surface roughness-Ra) and light microscopy. Histological and blood metal ion concentration analyses were performed in a sub-sample of patients.ResultsThe median (IQR) PE wear rate was 14 (6 to 20) mm3/year. Microscopic examination of the superior surface of trays exhibited pitting on 132 (59%) of trays. There was a statistically significant (p<0.05) increase in Rvk on the pitted area of trays for each design, indicating material removal from the pits compared to the unpitted area. The inferior surface of 116(51%) of trays displayed polishing, indicative of abrasive wear. The median(range) Co and Cr concentrations were 2.5µg/l (0.2–69.4) and 1.7µg/l (0.5-12.5) respectively in 40 patients. Of the tissue samples examined in 30 patients, 6 had at least “mild”-ALVAL infiltrate. All corresponding “ALVAL” explants were found to be pitted and/or show evidence of loosening of the tray.ConclusionThis study provides further evidence that CoCr release in TKR appears to be an under-appreciated cause of adverse clinical outcomes. The generation of metal particles was predominantly from the metal tray, which may explain elevated metal ions after TKRs, despite no direct metal-on-metal contact.

ObjectivesWe identified an unusual pattern of backside deformation on polyethylene (PE) inserts of contemporary total knee replacements (TKRs). The PE backside's margins were inferiorly deformed in TKRs with NexGen central-locking trays. This backside deformation was significantly associated with tray debonding. Furthermore, recent studies have shown high rate of tray debonding in PS NexGen TKRs. Subsequently, a field safety notice was issued regarding the performance of this particular device combination and the Option tray has been withdrawn from use. Therefore, we hypothesised that the backside deformation of PS inserts may be greater than that of CR inserts.Design and MethodsAt our national implant retrieval centre, we used peer-reviewed techniques to analyse changes in the bearing wear rate and backside surface deformation of NexGen PE inserts using coordinate measuring machines [N=84 (CR-43 and PS-41) TKRs with non-augmented-trays]. Multiple regression was used to determine which variable had the greatest influence on backside deformation. The amount of cement cover on trays was quantified as a %of the total surface using Image-J software.ResultsThe median (IQR) bearing wear rate of the PS PEs [14(8-22) mm3/year] was not significantly different(p=0.154) to that of the CR PEs [18(8-27)mm3/year]. The median (IQR) backside deformation of the PS inserts [294(239-361) µm] was significantly greater (p<0.001) than that of the CR inserts [212(158-258)µm]. Multiple regression modelling showed that duration in-vivo (p=0.037), central-clearance between insert and tray (p<0.001) and constraint (p=0.003) were significantly associated with PE backside-deformation. 38(93%) PS and 31(72%) of CR trays exhibited ≤10% of cement cover. Non-contacting profilometry and microscopy revealed marked pitting and abrasive changes to the superior surface of the tray.ConclusionThis explant study showed the PE backside deformation was significantly higher in PS than in CR inserts and this may be one explanation for the unsatisfactory clinical performance reported with this device combination.

BACKGROUND:Synthetic grafts have been used for a number of years in anterior cruciate ligament (ACL) reconstruction surgery. One of the more recent additions to the stable of synthetic ligaments is the Ligament Augmentation and Reconstruction System (LARS) ligament. PURPOSE:To analyze the biomechanics and histology of LARS grafts retrieved due to failure of the device. STUDY DESIGN:Descriptive laboratory study. METHODS:A total of 22 LARS ligament grafts that were explanted from patients were sent for analysis. Five new, unused samples of the standard LARS ACL graft were also analyzed. Biomechanical testing was performed: ultimate tensile force, force versus displacement, and stress versus strain were recorded. Histopathological examination was performed looking for degree of fibrous tissue ingrowth as well as the presence of a foreign body reaction. RESULTS:Of the 22 grafts retrieved, 14 were used for ACL grafts, 1 for a lateral collateral ligament graft, 2 for medial collateral ligament grafts, 4 for gluteal tendon augmentation, and 1 for a supraspinatus augmentation. A severe foreign body reaction was found in 86% of the grafts (18/22) and a mild foreign body reaction in the remaining 14% (4/22). Tissue ingrowth was minimal in the majority of ACL grafts; the other grafts showed moderate tissue ingrowth. Maximal tensile force was significantly higher for the new ACL grafts (mean ± SD, 1667 ± 845 N) compared with the retrieved grafts (897 ± 395 N; P < .05). CONCLUSION:This study demonstrated that the vast majority of retrieved LARS artificial ligaments had a florid foreign body reaction. There was minimal tissue ingrowth in ACL grafts and moderate ingrowth in other grafts. Retrieved grafts had a decreased ultimate tensile force, which increased their risk of rupture. CLINICAL RELEVANCE:Surgeons should be cautious in choosing to use these grafts in reconstructive surgery for patients.

Background: Fretting corrosion at modular junctions contributes to arthroplasty failure. Currently, no evidence-based guidelines are available regarding the acceptable level of trunnion corrosion that can occur in vivo. We aimed to examine the relationship between trunnion corrosion and risk of re-revision to assist surgeons with intraoperative decision making. Method: Grading by 3 independent examiners of revised and re-revised head components was performed using a modified Goldberg corrosion scale. Samples were separated into low-grade (LG) and high-grade (HG) corrosion. Mechanical testing determined the relationship between corrosion severity and pull-off strength at the head-stem junction. Results: 529 retrieved femoral heads were analysed. A positive association was detected between males and HG corrosion (OR 2.07; 95% CI, 1.45–2.94; p < 0.001). No difference between the survivorship of LG and HG heads was detected ( p-value = 0.247). In the re-revised sample, the first implant had a time in situ that was on average 7.97 years longer (95% CI, 5.4–10.6) than that of the subsequent re-revised femoral head. Severe corrosion on the first head was associated with a 37.5 (95% CI, 4.00–1944) fold increase of HG on the subsequent head ( p < 0.001). Femoral disassembly force had a positive correlation with stem taper corrosion grade ( p = 0.001). Conclusions: A well-fixed stem with corrosion may remain in situ.

Background: Although the Pinnacle Acetabular Hip System (DePuy Synthes) has demonstrated excellent survivorship results since it was first introduced in 2003, there have been a growing number of cases indicating that Pinnacle liners may be subject to a higher-than-expected rate of early dissociation failure. Between 2006 and 2020, our Centre received 212 retrieved Pinnacle liners from Western Australian hospitals. Of these, 26 were removed due to liner dissociation. Methods: To better understand the frequency and cause of this complication we assessed all retrieved Pinnacle acetabular components for type, damage modes and patient demographics. The leverage force required to dissociate Pinnacle liners was also measured and compared with another commonly used acetabular system, the Trident (Stryker Orthopaedics). Results: The estimated minimum incidence of liner dissociation from our data was 0.35%. Characterisation of dissociated Pinnacle cases (n = 26) revealed 73% were female with an average age of 59 compared to all retrieved Pinnacle cases (n = 212) where 58% were female with an average age of 66. Retrieval analysis indicated plastic deformation of the liner into an ovoid shape, signs of impingement on the rim postero-superiorly and shearing of the liner’s anti-rotation tabs was common. Mechanical testing indicated that the dissociation strength of Pinnacle cups decreases at approximately 6.6 N/year in situ (p = 0.01). Conclusion: The survival rate of Pinnacle acetabular cups is exceptional with only 5% revised at 10 years. However, surgeons should be aware of the clinical symptoms and high-risk demographics when assessing patients with polyethylene Pinnacle liners.

Selective laser melting (SLM) or powder bed fusion is a type of additive manufacturing technology with applications in, e.g., the orthopedics, energy, and aerospace industries. Several studies investigated the localized corrosion behavior of SLM-fabricated Type 316L (UNS S31603) stainless steel. However, little is known about the effects of tribocorrosive conditions on the response of stainless steels fabricated by SLM. In this study, the effects of third-body abrasive particles on the tribo-electrochemical behavior of SLM 316L stainless steel produced by SLM were investigated and compared with wrought counterparts (including UNS S31703, 317W) in 0.6 M NaCl. It was found that the presence of Mo played a more decisive role in the tribocorrosion behavior than the manufacturing method, i.e., 317W revealed the best tribocorrosion behavior vis-a-vis wrought 316L and the SLM-fabricated specimens. The improved tribocorrosion behavior contrasted with the much higher breakdown potential of the SLM-fabricated samples. Nano-scale secondary ion mass spectroscopy was used to investigate the effects of Mo on passivity. The implications of passivity and tribocorrosion behavior are discussed.

Background Over five million joint replacements are performed across the world each year. Cobalt chrome (CoCr) components are used in most of these procedures. Some patients develop delayed-type hypersensitivity (DTH) responses to CoCr implants, resulting in tissue damage and revision surgery. DTH is unpredictable and genetic links have yet to be definitively established. Methods At a single site, we carried out an initial investigation to identify HLA alleles associated with development of DTH following metal-on-metal hip arthroplasty. We then recruited patients from other centres to train and validate an algorithm incorporating patient age, gender, HLA genotype, and blood metal concentrations to predict the development of DTH. Accuracy of the modelling was assessed using performance metrics including time-dependent receiver operator curves. Results Using next-generation sequencing, here we determine the HLA genotypes of 606 patients. 176 of these patients had experienced failure of their prostheses; the remaining 430 remain asymptomatic at a mean follow up of twelve years. We demonstrate that the development of DTH is associated with patient age, gender, the magnitude of metal exposure, and the presence of certain HLA class II alleles. We show that the predictive algorithm developed from this investigation performs to an accuracy suitable for clinical use, with weighted mean survival probability errors of 1.8% and 3.1% for pre-operative and post-operative models respectively. Conclusions The development of DTH following joint replacement appears to be determined by the interaction between implant wear and a patient’s genotype. The algorithm described in this paper may improve implant selection and help direct patient surveillance following surgery. Further consideration should be given towards understanding patient-specific responses to different biomaterials.

BACKGROUND:Aseptic loosening is reported as the leading cause of revision total knee arthroplasty on the Australian National Joint Replacement Registry. Loosening of cemented tibial baseplates has been correlated with type of cement used, cementing technique, and cement contamination with biological material. The aim of this study was to evaluate the effect of cementing application and techniques including surface contamination and cement viscosity on fixation strength of tibia baseplates/cement interface.METHODS:Mechanical assessment of the fixation strength of tibia baseplates/cement interface was tested using a pull-out test on a material testing system. Different tibial baseplate design, cementing techniques, cement viscosity and contamination of the implant/cement interface with bone marrow were assessed to determine if they influenced force required to disrupt the cement/implant interface (pull-out strength).FINDINGS:The model with contamination of the cement prosthesis interface demonstrated a lower pull-out strength (p < 0.001). The model with the keel and baseplate cemented showed a higher pull-out strength compared to cementing the baseplate alone (p < 0.001). The use of low-viscosity cement resulted in a significantly higher failure force (p = 0.002) compared to high-viscosity cement when cementing the baseplate alone.INTERPRETATIONS:Biomechanical testing demonstrated improved fixation with cementing the tibial keel and keeping surfaces free from contamination during the cementation process.

TiO2 coatings were fabricated by anodization of Ti6Al4V in 1 M H3PO4 or H2SO4, at room temperature at 120 V for 10 min, and followed by annealing at 300 degrees or 500 degrees C for 8 h. Analyses include mineralogy (GAXRD, Raman), chemistry (XPS), morphology and microstructure (FESEM, FIB, 3D confocal microscopy), thermodynamic, optical (UV-Vis), and photocatalytic performance (MB degradation). The present work highlights factors that govern the nature of the materials and their performance. The influence of the oxidation strength of the acid is pervasive in that it impacts on the crystallinity, microstructural homogeneity, coating thickness, Ti3+ concentration, gas generation during arcing to form pores, and resultant pore size and distribution density. A key observation is that the pores form a subsurface network of variable continuity, which has a significant impact on the surface area and associated density of photocatalytically active sites, access by liquids and gases inside the coating, penetration depth of incident radiation, gas condensation, and residual liquid trapping. These data and the related thermodynamic analyses of the acids, anodization processes, and oxidation processes facilitate the generation of schematic models for the anodization mechanisms and the resultant surface, bulk, and micro structural effects that dominate the photocatalytic performance.

Aims The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs). Methods At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE. Regression modelling was used to identify variables related to the amount of cement cover on the retrieved trays. Results A total of 114 explanted fixed-bearing TKAs were examined. This included 76 used with contemporary PE inserts which were compared with 15 used with older generation PEs. The Attune and NexGen (central locking) trays were found to have significantly less cement cover than Triathlon and PFC trays (peripheral locking group) (p = 0.001). The median planicity values of the PE inserts used with central locking trays were significantly greater than of those with peripheral locking inserts (205 vs 85 microns; p < 0.001). Attune and NexGen inserts had a characteristic pattern of backside deformation, with the outer edges of the PE deviating inferiorly, leaving the PE margins as the primary areas of articulation. Conclusion Explanted TKAs with central locking mechanisms were significantly more likely to debond from the cement mantle. The PE inserts of these designs showed characteristic patterns of deformation, which appeared to relate to the manufacturing process and may be exacerbated in vivo. This pattern of deformation was associated with PE wear occurring at the outer edges of the articulation, potentially increasing the frictional torque generated at this interface.

A new method was developed to study the complex corrosion mechanism found in modular hip arthroplasty, i.e., dynamic crevice corrosion. Short wear events followed by rest times were applied in a conformal tribocontact to simulate different activity levels. Likewise, stepped potentiostatic polarization testing and electron microscopy were used to compare dynamic (continuous and interrupted) and static conditions. Results showed that 316L stainless steel underwent severe corrosion under the dynamic setting. The findings reproduced the extent and morphology of attack found in a retrieved implant. Thus, the new method could be used to investigate the corrosion susceptibility of modular hip arthroplasty.

Purpose: Modular Morse tapered femoral arthroplasty stems have been used for many years with great success and minimal complications. 1 stem, the Accolade by Stryker is noted to have increased failure when used in combination with LFIT V40 CoCr or the MITCH CoCr femoral heads. The failure has been in the form of corrosion, metallosis, fretting and trunnion fracture. This paper explores 10 cases with trunnion failure. Methods: A retrospective retrieval analysis of ten femoral stems retrieved at four different centres across Western Australia over a 3-year time frame. Inclusion criteria for this analysis included the use of Accolade 1 TMZF femoral stem plus either a MITCH or LFIT modular head. Results: 10 Accolade I (Stryker) stems were retrieved as part of the analysis, 6 with the LFIT V40 36-mm femoral head and 4 with a MITCH TRH femoral head. Average in situ time was 8.9 years. The hips were revised for either trunnion dislocation (6 cases) or trunnion fracture (4 cases). A characteristic destructive wear pattern of the femoral taper (trunnion) a "bird beak" appearance was present in all stems. This wear pattern created excessive movement and loosening resulting in a trunnion/head dislocation or brittle fracture of the trunnion. Conclusions: Catastrophic femoral neck fracture was likely due to a combination of material composition mismatch and mechanically assisted fretting corrosion at the head-neck junction leading to gross metallosis and failure. We suggest a recall on patients with an Accolade 1 stems in combination with a 36-mm or above LFIT or MITCH head, and for these patients to have clinical and radiological review.