Introduction. We aimed to identify genes associated with the development of ALVAL at relatively low levels of wear. Methods. At our unit all patients undergoing revision of a MoM hip prosthesis have periprosthetic tissue samples graded for ALVAL. Explants undergo volumetric wear testing of the bearing and taper surfaces. We identified patients with moderate/severe ALVAL who had been exposed to lower than the median wear rate of all recorded patients who had developed ALVAL (<3mm. 3. /year). This was termed the “ALVAL” group. We then identified all patients whose tissues had shown no signs of ALVAL. The patients in the two groups were sent buccal DNA collection kits. DNA was examined using next generation sequencing. Alleleic frequencies in the two groups were compared using Fisher's test and compared to a background UK population group (n=8514). We then conducted binary logistic regression with patient age, sex, primary source of debris (taper/bearing) and HLA genotype as the predictors. With the hypothesis that a cobalt/albumin metalloprotein acts as the epitope, we used validated binding prediction software to determine the relative affinities of the binding grooves created by different DQA1/DQB1 genetic combinations for albumin derived peptides. Given the protection that male sex and younger age appears to confer against ALVAL, we hypothesized that testosterone peptides may compete for these binding sites. Results. 28 ALVAL and 37 non ALVAL patients returned their samples for testing. The frequencies of DQA1∗05:05 and DQB1∗03:01 were significantly greater in the ALVAL groups(p=0.018). The variables positively associated with ALVAL were female sex(0.021), increasing age(0.003) and DQA1/DQB1 combinations with greater binding affinity for albumin fragments(0.03). Greater binding affinities for testosterone peptides were inversely related to ALVAL(0.05). Discussion. Common immune genotypes are associated with a greater risk of ALVAL. Conclusion. The evidence base on which MoM follow up protocols are based should be re-evaluated in light of these findings and future studies designed accordingly

Introduction: There are ongoing concerns regarding metal wear debris following the use of metal-on-metal (MonM) bearings for hip surface and total arthroplasty. A Type IV Hypersensitivity reaction to MonM articulations has previously been identified (aseptic lymphocyte dominated vasculitis associated lesion, ALVAL) but little is known of its incidence, diagnosis or management. Persisting groin pain in MonM patients may be undiagnosed ALVAL. At our single centre we have reviewed and compared three types of MonM articulations to examine the incidence of ALVAL and to identify trends. Methods: The resurfacing group comprised 250 patients with the ASR prosthesis. In the resurfacing hybrid total hip replacement (THR) group there were 86 patients implanted with an ASR head on a stem. The final group comprised of 625 patients with a MonM THR using a 36mm Pinnacle head. Both the S-ROM and the Corail stems were used in the THR groups. Patients with persisting and activity-restricting groin pain had tests for infection. Patients were counselled and revision was offered if ALVAL was suspected from the clinical picture, blood results and the aspiration result. Specimens for microbiological and histological analysis were taken at the time of revision. Results: We found 5 cases of histologically proven ALVAL in the absence of infection in 961 patients. The incidence was: 1.2% in the resurfacing group, 2.3% of Resurfacing Hybrid THR group and 0 in the 36 mm THR group. All 5 cases were in female patients. Only 1 case had any radiological abnormality. One patient was initially revised from a resurfacing to a 36mm MonM THR without clinical success. All patients have now been revised to ceramic-on-ceramic bearings with improvements in outcome. Discussion: ALVAL may be under-diagnosed. The 5 patients we describe showed good clinical recovery following their primary procedure. However, activity levels decreased and pain increased at 6–12 months post-op. All described non-specific systemic symptoms. On examination, a painful straight leg raise was a characteristic finding. This may result from the significant effusion found around the hip at each revision. Fluid aspirated from these hips was of a characteristic colour (green grey) and viscosity. The failure of the revision of a resurfacing to a smaller MonM bearing highlights the problem of sensitisation to the metal debris. Any subsequent revision to a MonM bearing is unlikely to improve clinical outcome. This finding is consistent with previous reports in the literature. Our results suggest the incidence of ALVAL may be higher that previously thought. We suggest all patients with significant groin pain should have inflammatory markers tests and a hip aspiration performed. In the absence of infection, revision to an alternative bearing surface may be indicated

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. Hip resurfacing remains a potentially valuable surgical procedure for appropriately-selected patients with optimised implant choices. However, concern regarding high early failure rates continues to undermine confidence in use. A large contributor to failure is adverse local tissue reactions around metal-on-metal (MoM) bearing surfaces. Such phenomena have been well-explored around MoM total hip arthroplasties, but comparable data in equivalent hip resurfacing procedures is lacking. In order to define genetic predisposition, we performed a case-control study investigating the role of human leucocyte antigen (HLA) genotype in the development of pseudotumours around MoM hip resurfacings. Methods. A matched case-control study was performed using the prospectively-collected database at the host institution. In all, 16 MoM hip resurfacing 'cases' were identified as having symptomatic periprosthetic pseudotumours on preoperative metal artefact reduction sequence (MARS) MRI, and were subsequently histologically confirmed as high-grade aseptic lymphocyte-dominated vasculitis-associated lesions (ALVALs) at revision surgery. ‘Controls’ were matched by implant type in the absence of evidence of pseudotumour. Blood samples from all cases and controls were collected prospectively for high resolution genetic a nalysis targeting 11 separate HLA loci. Statistical significance was set at 0.10 a priori to determine the association between HLA genotype and pseudotumour formation, given the small sample size. Results. Using a previously-reported ALVAL classification, the majority of pseudotumour-positive caseswere found to have intermediate-grade group 2 (n = 10; 63%) or group 3 (n = 4; 25%) histological findings. Two further patients (13%) had high-grade group 4 lesions. HLA-DQB1*05:03:01 (p = 0.0676) and HLA-DRB1*14:54:01 (p = 0.0676) alleles were significantly associated with a higher risk of pseudotumour formation, while HLA-DQA1*03:01:01 (p = 0.0240), HLA-DRB1*04:04:01 (p = 0.0453), HLA-C*01:02:01 (p = 0.0453), and HLA-B*27:05:02 (p = 0.0855) were noted to confer risk reduction. Conclusion. These findings confirm the association between specific HLA genotypes and the risk of pseudotumour development around MoM hip resurfacings. Specifically, the two ‘at risk’ alleles (DQB1*05:03:01 and DRB1*14:54:01) may hold clinical value in preoperative screening and prospective surgical decision-making. Cite this article: Bone Jt Open 2023;4(3):182–187

Aims

This study compared the cobalt and chromium serum ion concentration of patients treated with two different metal-on-metal (MoM) hinged total knee arthroplasty (TKA) systems, as well as a titanium nitride (TiN)-coated variant.

We present a series of 35 patients (19 men and 16 women) with a mean age of 64 years (36.7 to 75.9), who underwent total hip replacement using the ESKA dual-modular short stem with metal on-polyethylene bearing surfaces. This implant has a modular neck section in addition to the modular head. Of these patients, three presented with increasing post-operative pain due to pseudotumour formation that resulted from corrosion at the modular neck-stem junction. These patients underwent further surgery and aseptic lymphocytic vaculitis associated lesions were demonstrated on histological analysis.

Retrieval analysis of two modular necks showed corrosion at the neck-stem taper. Blood cobalt and chromium levels were measured at a mean of nine months (3 to 28) following surgery. These were compared with the levels in seven control patients (three men and four women) with a mean age of 53.4 years (32.1 to 64.1), who had an identical prosthesis and articulation but with a prosthesis that had no modularity at neck-stem junction. The mean blood levels of cobalt in the study group were raised at 50.75 nmol/l (5 to 145) compared with 5.6 nmol/l (2 to 13) in control patients.

Corrosion at neck-stem tapers has been identified as an important source of metal ion release and pseudotumour formation requiring revision surgery. Finite element modelling of the dual modular stem demonstrated high stresses at the modular stem-neck junction. Dual modular cobalt-chrome hip prostheses should be used with caution due to these concerns.

A 70-year-old man with an uncemented metal-on-polyethylene total hip prosthesis underwent revision arthroplasty 33 months later because of pain, swelling and recurrent dislocation. There appeared to be corrosion and metal release from the prosthetic head, resulting in pseudotumour formation and severe local soft-tissue destruction. The corrosion occurred at the junction between the titanium-molybdenum-zirconium-iron taper and the cobalt-chrome-molybdenum head, but the mechanism was unproven.

Objectives. We have encountered patients who developed large joint fluid collections with massive elevations in chromium (Cr) and cobalt (Co) concentrations following metal-on-metal (MoM) hip arthroplasties. In some cases, retrieval analysis determined that these ion concentrations could not be explained simply by the wear rates of the components. We hypothesized that these effects may be associated with aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Patients and Methods. We examined the influence of the ALVAL grade on synovial fluid Co and Cr concentrations following adjustment for patient and device variables, including volumetric wear rates. Initially restricting the analysis to include only patients with one MoM hip resurfacing device, we performed multiple regression analyses of prospectively collected data. We then repeated the same statistical approach using results from a larger cohort with different MoM designs, including total hip arthroplasties. Results. In the resurfacing cohort (n = 76), the statistical modelling indicated that the presence of severe ALVAL and a large fluid collection were associated with greater joint fluid Co concentrations after adjustment for volumetric wear rates (p = 0.005). These findings were replicated in the mixed implant group (n = 178), where the presence of severe ALVAL and a large fluid collection were significantly associated with greater fluid Co concentrations (p < 0.001). Conclusion. The development of severe ALVAL is associated with elevations in metal ion concentrations far beyond those expected from the volumetric loss from the prosthetic surfaces. This finding may aid the understanding of the sequence of events leading to soft-tissue reactions following MoM hip arthroplasties. Cite this article: D. J. Langton, R. P. Sidaginamale, T. J. Joyce, J. G. Bowsher, J. P. Holland, D. Deehan, A. V. F. Nargol, S. Natu. Aseptic lymphocyte-dominated vasculitis-associated lesions are related to changes in metal ion handling in the joint capsules of metal-on-metal hip arthroplasties. Bone Joint Res 2018;7:388–396. DOI: 10.1302/2046-3758.76.BJR-2018-0037

Objectives. We investigated the reliability of the cobalt-chromium (CoCr) synovial joint fluid ratio (JFR) in identifying the presence of a severe aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) response and/or suboptimal taper performance (SOTP) following metal-on-metal (MoM) hip arthroplasty. We then examined the possibility that the CoCr JFR may influence the serum partitioning of Co and Cr. Methods. For part A, we included all revision surgeries carried out at our unit with the relevant data, including volumetric wear analysis, joint fluid (JF) Co and Cr concentrations, and ALVAL grade (n = 315). Receiver operating characteristic curves were constructed to assess the reliability of the CoCr JFR in identifying severe ALVAL and/or SOTP. For part B, we included only patients with unilateral prostheses who had given matched serum and whole blood samples for Co and Cr analysis (n = 155). Multiple regression was used to examine the influence of JF concentrations on the serum partitioning of Co and Cr in the blood. Results. A CoCr JFR > 1 showed a specificity of 83% (77% to 88%) and sensitivity of 63% (55% to 70%) for the detection of severe ALVAL and/or SOTP. In patients with CoCr JFRs > 1, the median blood Cr to serum Cr ratio was 0.99, compared with 0.71 in patients with CoCr JFRs < 1 (p < 0.001). Regression analysis demonstrated that the blood Cr to serum Cr value was positively associated with the JF Co concentration (p = 0.011) and inversely related to the JF Cr concentration (p < 0.001). Conclusion. Elevations in CoCr JFRs are associated with adverse biological (severe ALVAL) or tribocorrosive processes (SOTP). Comparison of serum Cr with blood Cr concentrations may be a useful additional clinical tool to help to identify these conditions. Cite this article: D. J. Langton, S. Natu, C. F. Harrington, J. G. Bowsher, A. V. F. Nargol. Is the synovial fluid cobalt-to-chromium ratio related to the serum partitioning of metal debris following metal-on-metal hip arthroplasty? Bone Joint Res 2019;8:146–155. DOI: 10.1302/2046-3758.83.BJR-2018-0049.R1

Cobalt chrome alloy is commonly used in joint replacement surgery. However, it is recognised that some patients develop lymphocyte mediated delayed type hypersensitivity (DTH) responses to this material, which may result in extensive bone and soft tissue destruction. Phase 1. United Kingdom: From an existing database, we identified extreme phenotype patient groups following metal on metal (MoM) hip resurfacing or THR: ALVAL with low wearing prostheses; ALVAL with high wear; no ALVAL with high wear; and asymptomatic patients with implants in situ for longer than ten years. Class I and II HLA genotype frequency distributions were compared between these patients’ groups, and in silico peptide binding studies were carried out using validated methodology. Phase 2. United Kingdom: We expanded the study to include more patients, including those with intermediary phenotypes to test whether an algorithm could be developed incorporating “risk genotypes”, patient age, sex and metal exposure. This model was trained in phase 3. Phase 3. United Kingdom, Australia, United States. Patients from other centres were invited to give DNA samples. The data set was split in two. 70% was used to develop machine learning models to predict failure secondary to DTH. The predictions were tested using the remaining blinded 30% of data, using time-dependent AUROCs, and integrated calibration index performance statistics. A total of 606 DNA samples, from 397 males and 209 female patients, were typed. This included 176 from patients with failed prostheses, and 430 from asymptomatic patients at a mean of >10 years follow up. C-index and ROC(t) scores suggested a high degree of discrimination, whilst the IBS indicated good calibration and further backed up the indication of high discriminatory ability. At ten years, the weighted mean survival probability error was < 4%. At present, there are no tests in widespread clinical use which use a patient's genetic profile to guide implant selection or inform post-operative management. The algorithm described herein may address this issue and we suggest that the application may not be restricted to the field of MoM hip arthroplasty

Background. Pseudotumor or high grade ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) development around total hip replacements secondary to local metal debris generation – especially in the setting of metal-on-metal bearings – is a well-recognised histopathologic phenomenon. Recent work has suggested a strong genetic correlation with an individual's risk of such lesion development following metal exposure. Emerging data have highlighted a similar potential concern around total knee replacements (TKRs), particularly with increasing construct modularity. To date, the body-of-knowledge pertaining to TKR-associated ALVALs has largely been limited to individual case reports or small retrospective case series’, with no large-scale investigation looking at this potential complication. This study sought to establish the preliminary prevalence of pseudotumor or high grade ALVAL formation seen at the revision of primary TKRs and to establish the correlation between histologic ALVAL grade and patient-reported functional outcomes. Methods. Findings of 1263 consecutive patients undergoing revision knee surgery, at a high-volume referral center, were reviewed. 161 cases of active infection were excluded. Complete histopathology reports were subsequently available for 321 (29.1%) non-infective cases. Each case was independently histologically-classified using a previously validated scoring system reflecting ALVAL grade. Post-operative patient-reported outcomes measures (PROMs) were available for 134 patients (41.7%), allowing direct correlation between functional performance and the established histopathology results. Results. In total, 23 high grade lesions were identified, including 5 distinct pseudotumors, representing 7.2% (23/321) of the cohort. When compared by histologic grade, Jonkeere-Terpstra testing yielded P-values of 0.02 and 0.03 for the Oxford Knee Score and WOMAC datasets, respectively, suggesting a high correlation between ALVAL grade and functional knee scores. Conclusions. The results of this large histologic analysis suggest a prevalence of pseudotumor or high grade ALVAL development at revision TKR surgery of greater than 7%. This unexpectedly high result may contribute clinical insight into the previously under-appreciated significance of metal debris-related local tissue reactions around TKRs. The findings herein also demonstrate a strong near-linear inverse relationship between patient-reported clinical knee performance and the underlying histologic grade of local tissue reaction. Collectively, this information may provide some further understanding of a proportion of the widely quoted 15–20% of patients who remain dissatisfied with their TKR after surgery. This result has potential diagnostic and management implications for clinicians treating patients with underperforming in situ TKRs and should prompt consideration of an ALVAL secondary to local wear debris-generated metallosis in the differential diagnosis

Introduction. In 2010, a widely used metal-on-metal hip implant was voluntarily recalled from the market by the manufacturer. Our lab performed detailed retrieval analysis of 548 of the explanted devices and 165 periprosthetic tissue specimens. We reported a high degree of variability in the multiple measurements that we performed on the components, including volumetric wear. Other studies using semi-quantitative tissue grading methods to describe the histology of the periprosthetic tissues from metal-on-metal hips have looked for relationships between component wear and histological features. Grammatopoulos et al found higher ALVAL scores in 45 hip resurfacing patients with pseudotumors compared to 11 without pseudotumors and a moderately positive correlation between wear and the histological rankings for tissue necrosis and lymphocytic response. We examined correlations between the component wear measurements from retrieval analysis and the tissue features in this large group of one metal-on-metal hip design. Materials and Methods. Tissues were processed routinely into paraffin sections, stained with H&E and characterized with light microscopic semi-quantitative scores for ALVAL features and for the number of macrophages and lymphocytes, extent of metal debris and the estimated percentage of necrosis per slide. Spearman correlation analysis was conducted to evaluate any correlations between retrieval wear measurements and histological findings. Results. The median combined cup and ball wear volume was 17.5mm3 in these 165 cases. The median tissue ALVAL score was 5.5 out of 10. Component total wear volume was not predictive of the ALVAL score (P = 0.09, R = −0.007) or the number of lymphocytes (P= 0.170, R= −0.077) but there was a positive correlation between wear volume and the ranking for macrophages in the tissues (P< 0.001, R=0.215). No other correlations were found for component wear. The median time to revision was 4.84 years. There was a negative correlation between tissue inflammation ranking (P=0.002, R=−0.183) and for lymphocyte ranking and time to revision (P=0.003, R=−0.173). There was a positive correlation between time to revision and the macrophage ranking (P=0.005, R=0.166). Conclusion. From this large-scale retrieval analysis of one design of metal-on-metal total hip, a high degree of variability was observed over the multiple analyses performed, including volumetric wear and tissue features. This likely reflects our previous observation that no single particular failure mechanism was predominant in this large cohort. Funded by DePuy Synthes Companies of Johnson & Johnson

Background. Some reports have suggested that debris generated from the head neck taper junction is more destructive than equivalent doses from metal bearing surfaces. Methods. Part 1. We examined the relationship between the source (taper/bearing) and volume of metal debris on Cr and Co concentrations in corresponding blood and hip synovial fluid samples and the observed agglomerated particle sizes in excised tissues using regression analysis of prospectively collected data at a single revision unit. Part 2. We investigated variables most strongly associated with macroscopic soft tissue injury as documented at revision surgery using ordinal logistic regression. Independent variables included source and volume of CoCr exposure, Cr and Co joint fluid concentrations, joint fluid grade, ALVAL (Aseptic Lymphocytic Vasculitis Associated Lesion) grade, presence of vascular hyalinisation, agglomerated particle size, implant type, patient sex and age. Results. A total of 199 explanted MoM hips were analysed. Multiple regression statistical modelling suggested that a greater source contribution of metal debris from the taper junction was associated with smaller aggregated particle sizes in the local tissues and a relative reduction of Cr ion concentrations in the corresponding synovial fluid and blood samples. There was an association between increasing Co concentrations in the joint fluid and an increasing ALVAL score (p<0.001). In contrast, higher Cr concentrations were inversely related to ALVAL (p<0.001). The ALVAL response was itself strongly associated with larger fluid collections (p<0.001). Vascular hyalinisation and larger fluid collections were significantly associated with macroscopic tissue injury (coefficient 2.22, p<0.001 for fluid grade and 4.35, p<0.001 for hyalinisation). Discussion. Metal debris generated from taper junctions appears to be associated with a different biochemical environment than debris generated from bearing surfaces. We believe that this finding may provide some explanation as to the poor performance of MoM THRs compared to the equivalent resurfacing devices and the confusion surrounding the significance of blood metal testing. Conclusion. Chromium does seem to inhibit the development of ALVAL

Introduction. The utilization of lymphocyte transformation testing (LTT) has increased for diagnosing metal sensitivity associated with TKA, but its validity for the diagnosis of TKA failure due to an immune reaction has not been established. Methods. We performed a retrospective study of 27 well-fixed, aseptic primary TKAs with persistent pain and/or stiffness, revised by a single, experienced surgeon for suspected metal allergy to nickel based on a positive LTT. Periprosthetic tissue samples obtained at the time of revision surgery were scored using the aseptic lymphocytic vasculitis-associated lesion (ALVAL) scoring system. Results. Eight patients were categorized as mildly reactive, 8 reactive, and 11 highly reactive to nickel by LTT. The predominant findings on routine histology were fibrosis and varying degrees of lymphocytic infiltration in 17/27 (63%) of the cases. The average ALVAL score of the cohort was 3.1 ± 1.9, out of a maximum score of 10. Average Knee Society Scores (KSS) improved post-revision, as did range of motion (all p<0.01). Neither LTT stimulation index as a continuous variable nor as a categorical variable (mild, moderate, high) was correlated with ALVAL score, pre-operative function, or change in function at last follow-up (0.015 < r < 0.30, 0.13 < p < 0.95) as measured by KSS. In addition, the ALVAL score did not correlate significantly with either pre-operative or post-operative KSS or range of motion (0.061 < r < 0.365, 0.09 < p < 0.88). Conclusions. Based on this analysis including histopathology, LTT results alone are insufficient for the diagnosis of TKA failure due to an immune reaction. A positive LTT may not indicate that an immune reaction is the cause of pain and stiffness post-TKA. The role of LTT in assessing immune failure of TKA needs further investigation. Diagnostic criteria for immune failure of a TKA need to be established

Hip resurfacing may be a useful surgical procedure when patient selection is correct and only implants with superior performance are used. In order to establish a body of evidence in relation to hip resurfacing, pseudotumour formation and its genetic predisposition, we performed a case-control study investigating the role of HLA genotype in the development of pseudotumour around MoM hip resurfacings. All metal-on-metal (MoM) hip resurfacings performed in the history of the institution were assessed. A total of 392 hip resurfacings were performed by 12 surgeons between February 1st 2005 and October 31st 2007. In all cases, pseudotumour was confirmed in the preoperative setting on Metal Artefact Reduction Sequencing (MARS) MRI. Controls were matched by implant (ASR or BHR) and absence of pseudotumour was confirmed on MRI. Blood samples from all cases and controls underwent genetic analysis using Next Generation Sequencing (NGS) assessing for the following alleles of 11 HLA loci (A, B, C, DRB1, DRB3/4/5, DQA1, DQB1, DPB1, DPA1). Statistical significance was determined using a Fisher's exact test or Chi-Squared test given the small sample size to quantify the clinical association between HLA genotype and the need for revision surgery due to pseudotumour. Both groups were matched for implant type (55% ASR, 45% BHR in both the case and control groups). According to the ALVAL histological classification described by Kurmis et al., the majority of cases (63%, n=10) were found to have group 2 histological findings. Four cases (25%) had group 3 histological findings and 2 (12%) patients had group 4 findings. Of the 11 HLA loci analysed, 2 were significantly associated with a higher risk of pseudotumour formation (DQB1*05:03:01 and DRB1*14:54:01) and 4 were noted to be protective against pseudotumour formation (DQA1*03:01:01, DRB1*04:04:01, C*01:02:01, B*27:05:02). These findings further develop the knowledge base around specific HLA genotypes and their role in the development of pseudotumour formation in MoM hip resurfacing. Specifically, the two alleles at higher risk of pseudotumour formation (DQB1*05:03:01 and DRB1*14:54:01) in MoM hip resurfacing should be noted, particularly as patient-specific genotype-dependent surgical treatments continue to develop in the future

Introduction: Hip Resurfacing has increased in popularity, particularly in young, active patients. However, concerns remain regarding metal ion levels, hypersensitivity leading to aseptic lymphocytic-vasculitis-associated lesions(ALVAL) and AVN. The purpose of this study was to document our experience of revising resurfacing arthroplasty for ALVAL. Methods: All patients undergoing conversion of hip resurfacing to total hip replacement at our institution were reviewed. The notes were reviewed for the reason for revision, the make of the implant, time interval between primary procedure and revision and final diagnosis. Radiographs were reviewed to assess for implant alignment, signs of loosening, neck thinning and AVN. Results: Out of the 34 patients who had revision surgery 13 were revised for suspected ALVAL, with mean age of 58.8 years at a mean 42.9 months following primary surgery. Of the 13 resurfacings revisions 11 were Birmingham resurfacing and 1 each of Cormet and ASR resurfacing. Groin pain was the presenting complaint in all patients, 5 patients developed their symptoms immediately postoperatively whilst 8 developed symptoms at mean 28.25 months. Haematological investigations were non-diagnostic. Radiographs were normal in 4 patients, whilst 4 demonstrated a loose cup. Thinning of femoral neck and vertical cup alignment were present in 2 patients each while 1 patient had both vertical cup and thinning of femoral neck. All revisions were achieved with primary implants and all patients had immediate pain relief after surgery. Implants and tissue were sent for laboratory analysis. 3 patients had a confirmed histological diagnosis of ALVAL, the remaining cases had identical operative findings and are presumed ALVAL. Discussion: ALVAL accounts for nearly 1/3 of all our revisions for failed resurfacing arthroplasty. Unexplained pain in patients with resurfacing arthroplasty should be considered for a diagnosis of ALVAL and investigated appropriately. Symptoms tend to resolve reliably following conversion to total hip arthroplasty

Background. Pseudotumours have been associated with metal-on-metal (MoM) hip replacements. We define it as a solid mass which may have cystic components that is neither neoplastic nor infectious in aetiology. The cause of a pseudotumour is not fully understood but could be due to excessive wear, metal hypersensitivity or due to an as-yet unknown cause. Aim. We present the retrieval analysis of early failure MoM hips revised for pain, loosening or a symptomatic mass. Tissues and implants were examined for the possible causes of failure and pseudotumour formation. Corrosion as a potential new cause for pseudotumour formation will be presented. Methods. A group of 16 MoM hip replacements were collected for retrieval analysis. Six of which had a pseudotumour. An Artificial Hip Profiler (Redlux Ltd) was used to measure wear. Edge loading was determined using the 3D wear data. Tissues were histologically evaluated using a 10-point ALVAL scoring system, which strongly suggests hypersensitivity (1). Cases were assigned to one of three categories: high wear (rates >5m/yr), hypersensitivity or corrosion. Results. Of the 6 pseudotumours, 3 had edge loading, 2 had high ALVAL scores and one had corrosion at the head taper junction. The high wear group, (3 cases) all demonstrated edge loading. Histology revealed more metal wear particles and macrophages, with a low ALVAL score in these cases. Two cases were found to have hypersensitivity with a high ALVAL score, more lymphocytes with less visible wear debris and macrophages. The wear rates were also lower, <4m/yr. One total hip replacement had corrosion at the junction between the head and adaptor taper for the stem. The bearings had low wear and the tissue had extensive necrosis as well as products of corrosion enclosed in fibrin (2). There was no suggestion of hypersensitivity (low ALVAL score). Conclusion. Pseudotumours can be caused by high wear, but if this is ruled out, a hypersensitivity or corrosion product reaction should be considered

Introduction: There are ongoing concerns regarding metal wear debris following the use of metal-on-metal (MonM) bearings for hip surface and total arthroplasty. A Type IV Hypersensitivity reaction to MonM articulations has previously been identified (aseptic lymphocyte dominated vasculitis associated lesion, ALVAL) but little is known of its incidence, diagnosis or management. Persisting groin pain in MonM patients may be undiagnosed ALVAL. At our single centre we have reviewed and compared three types of MonM articulations to examine the incidence of ALVAL and to identify trends. Methods: The resurfacing group comprised 250 patients with the ASR prosthesis. In the resurfacing hybrid total hip replacement (THR) group there were 86 patients implanted with an ASR head on a stem. The final group comprised of 625 patients with a MonM THR using a 36mm Pinnacle head. Both the S-ROM and the Corail stems were used in the THR groups. Patients with persisting and activity-restricting groin pain had tests for infection. Patients were counselled and revision was offered if ALVAL was suspected from the clinical picture, blood results and the aspiration result. Specimens for microbiological and histological analysis were taken at the time of revision. Results: We found 5 cases of histologically proven ALVAL in the absence of infection in 961 patients. The incidence was: 1.2% in the resurfacing group, 2.3% of Resurfacing Hybrid THR group and 0 in the 36 mm THR group. All 5 cases were in female patients. Only 1 case had any radiological abnormality. One patient was initially revised from a resurfacing to a 36mm MonM THR without clinical success. All patients have now been revised to ceramic-on-ceramic bearings with improvements in outcome. Discussion: ALVAL may be under-diagnosed. The 5 patients we describe showed good clinical recovery following their primary procedure. However, activity levels decreased and pain increased at 6–12 months post-op. All described non-specific systemic symptoms. On examination, a painful straight leg raise was a characteristic finding. This may result from the significant effusion found around the hip at each revision. Fluid aspirated from these hips was of a characteristic colour (green grey) and viscosity. The failure of the revision of a resurfacing to a smaller MonM bearing highlights the problem of sensitisation to the metal debris. Any subsequent revision to a MonM bearing is unlikely to improve clinical outcome. This finding is consistent with previous reports in the literature. Our results suggest the incidence of ALVAL may be higher that previously thought. We suggest all patients with significant groin pain should have inflammatory markers tests and a hip aspiration performed. In the absence of infection, revision to an alternative bearing surface may be indicated

Metal-on-metal (MOM) hip resurfacings release chromium and cobalt wear debris into the surrounding joint. The hip tissue taken from failed MOM hips shows specific histological features including a subsurface band-like infiltrate of macrophages with particulate inclusions, perivascular lymphocytic infiltrate and fibrin exudation. This tissue response has been called Aseptic Lymphocytic Vasculitis Associated Lesion (ALVAL). There is a recognised carcinogenic potential associated with hexavalent chromium and epidemiological data from first generation MOM arthroplasties may suggest an increased incidence of haematological malignancy. The ALVAL type reaction includes a marked proliferation of lymphocytes in the perivascular space and thorough investigation of this lymphocytic response is warranted. This study aims to further characterise the lymphocytic infiltrate using immunohistochemistry and to test clonality using polymerase chain reaction (PCR). Tissues from revised all cause failed MOM hip arthroplasties (n=77) were collected and analysed initially using routine H&E staining. Those that met the diagnostic criteria of ALVAL described above (n=34) were further stained with a panel of immunohistochemical markers (CD3, CD4, CD8 (T-cell markers) and CD20 (B-cell marker)). 10 representative ALVAL cases were selected and sent for gene rearrangement studies using PCR to determine whether the lymphocytes were polyclonal or monoclonal in nature. The analysis of the lymphocytic aggregates in ALVAL, showed a mixed population of B and T cells. Within the aggregates, there was a predominance of B cells (CD20) over T cells (CD3). Of the 10 cases which were analysed by PCR, 7 were suitable for interpretation. None of these cases showed evidence of monoclonal lymphocyte proliferation. The carcinogenic potential of wear debris from MOM hips, particularly affecting the haematopoietic system should be investigated. This study has shown a predominantly B-lymphocyte response in tissues surrounding MOM hips which is polyclonal. Although the numbers are small, the study suggests an immune mediated response in MOM hip tissue and excludes a neoplastic proliferation. However, long term follow up of patients with MOM hips may be prudent

Background:. Higher than expected revision rates have been observed in large bearing metal-on-metal total hip replacements. We have introduced a metal on metal hip screening clinic at our unit and report the results. Methods:. All patients who had a metal-on-metal total hip replacement implanted at our unit were recalled to clinic. Screening consisted of clinical examination, Oxford hip score, radiographs, MARS MRI and serum cobalt/chromium ion levels. MRI scans were graded (Norwich Classification) by a single consultant radiologist who was blinded to the history, examination, and metal levels. Patients were sub-classified into 6 groups, which determined further follow up and were either entered into a regular screening programme or referred to a revision arthroplasty surgeon for a decision on whether revision was required. Results:. A total of 278 patients were identified. Four patients had moved away, 2 refused follow-up and 1 patient had died. This left 271 patients in our cohort, having 299 metal-on-metal hip replacements with a M:F ratio of 1.5:1 and a mean age of 61.9 years (29–87). 59 (21.8%) patients complained of a recent deterioration in symptoms. Sixty seven (24.7%) patients had an abnormal xray appearance of their hip replacement (inclination >50 degrees, loosening, or migration of prosthesis). Of the 232 hips which underwent MARS MRI, 118 (50.9%) were group A (normal appearance), 66 (28.4%) C1 (mild MOM disease), 31 (13.4%) C2 (moderate MOM disease), and 17 (7.3%) C3 (severe MOM disease). One hundred and seventeen (38.9%) had a substantial fluid collection around the hip. Serum cobalt/chromium metal ions were raised in 135 patients (49.5%), 46 of which had one (8.8%) or both (8%) above 7 ppb (chromium >134 nmol/L, cobalt > 119 nmol/L). One hundred and forty nine patients (55%) remained under review in the MOM clinic and 122 (45%, 148 hip replacements) were referred to a revision surgeon for specialist opinion. Of these 21 hips (14.2%) have been revised and a further 14 hips (9.5%) are awaiting revision. In total 64 hips (21.3% of all large head metal on metal hips implanted in our unit) have been revised with a further 22 (7.3%) listed for revision. Of these, 13 were histologically proven to be an ALVAL reaction, 19 had the classic clinical findings of ALVAL (but not histologically confirmed), and 1 was a non-specific reaction to metal wear. 53 patients (19.4%, 56 hips) were completely asymptomatic but had evidence of ALVAL soft tissue reaction on MRI and/or rising metal ion levels – 9 of these hips have already been revised for ALVAL and 6 more listed for revision. Conclusions. Our screening programme has identified 53 (19.6%) asymptomatic patients who have evidence of a suspicious reaction to their metal-on-metal hip replacements. 16 (3%) of these have gone on to revision. We would recommend all patients with a metal-on-metal total hip replacement in situ are fully screened for ARMD regardless of symptoms and metal ion levels

Introduction: Approximately 0.5 % of patients with metal on metal hip replacements develop post operative pain which is thought to be due to an immune reaction to metal wear particles, known as Aseptic Lymphocyte Dominated Vasculitis Associated Lesion (ALVAL). Treatment usually requires revision to a non metal on metal hip.. Is the development of ALVAL more likely in those patients with high wear rates?. Methods: Retrieved Metal on Metal (MOM) hip implants; periprosthetic tissue and blood samples were obtained from patients (n = 18) undergoing revision for unexplained pain at a mean of 2 years post operatively. The following variables were measured:. linear wear rate (depth of the femoral head and acetabular socket wear patch/time from operation);. the diagnosis and severity of ALVAL from histological sections of periprosthetic tissue (Wilhert grading system);. pre-revision whole blood cobalt, and chromium levels using Inductively Coupled Plasma Mass Spectrometry. All implants and tissue samples were analysed against control samples from patients undergoing revision of MOM hips for fractured femoral neck or impingement. Results: Linear wear rates of retrieved implants, and blood levels of cobalt and chromium from patients with unexplained plain were greater than from control patients. Histolopathological analysis of tissue showed dense inflammatory infiltrates with healthy looking endothelial cells in all vessels from both patient groups. Discussion and Conclusion: A painful MOM hip was associated with high wear rates and blood metal levels. The local inflammatory response was similar to “ALVAL”, ie lymphocyte dominated, but not exclusive to those patients with unexplained pain. We question whether ALVAL represents a vasculitis, or merely a classical lymphocyte driven inflammatory tissue response to metal debris particles

All patients with a MOM THR implanted at our unit were recalled for clinical examination, Oxford hip score, radiographs, MARS MRI and cobalt/chromium ion levels. Patients were sub-classified, determining further follow up: a regular screening programme or referral to a revision arthroplasty surgeon. We identified 299 MOM THR's. 59 patients reported a recent deterioration in symptoms. 67 had an abnormal x-ray. 232 hips underwent MARS MRI: 66 showed mild MOM disease, 31 moderate MOM disease, 17 severe MOM disease. 117 had a substantial fluid collection around the hip. Serum cobalt/chromium ions were raised in 135 patients. 46 had one or both above 7 ppb. 148 THR's were referred to a revision surgeon. 21 have been revised and 14 are awaiting revision. In total 64 hips have been revised. 13 were histologically proven ALVAL, 19 had clinical findings of ALVAL (not histologically confirmed), and 1 non-specific reaction to metal wear. 53 asymptomatic patients had evidence of soft tissue reaction on MRI and/or rising metal ions. Our screening programme identified asymptomatic patients with evidence of a suspicious reaction to their MOM THR. We recommend all patients with a MOM THR are fully screened for ARMD regardless of symptoms and metal ion levels

Young osteoarthritic male patients have been considered the ideal candidates for Metal-on-Metal (MoM) hip resurfacing arthroplasty (HRA), based on generally good long term results. In contrast, hip resurfacing in young female patients has become controversial. Recently, one implant manufacturer withdrew 46mm and smaller components, citing poorer than expected 10 year outcomes in females with smaller HRAs. Whether this difference is related to gender or to component size is still debated. Possible reasons for higher failure rates reported in females include higher rates of hip dysplasia, poorer bone quality and the risk of higher wear in some smaller sized implants with low cup coverage angles. We reviewed HRA revision specimens with the aim of comparing mode of failure, time to revision, femoral cement characteristics and acetabular bone attachment in specimens larger and smaller than 46mm and from male versus female patients. Methods. The study included all of the MoM HRA devices in our collection. Of the 284 hip resurfacing devices with complete clinical information, 131 were from male and 153 from female patients. Femoral sizes ranged from 36 – 58mm, median and mode 46mm; median size in females was 44 and 50mm in males. Time to failure ranged from 1 to 178 months, median 24 mos. Seven designs were represented but the majority were Conserve Plus (n=105 WMT, USA) and BHR (n=78 Smith & Nephew, USA) which differ in cementing technique. 131 femoral components were sectioned and the width of the cement mantle and the amount of cement in the head were measured. Where available, the amount of bone attached to the cup porous surface (n=91), tissue ALVAL scores (n=75) and bearing wear depth (n=138) were included in the multivariate analysis. Results. As a function of gender, there were no significant differences in time to revision, cement measurements or ALVAL scores. Wear depth was significantly higher in females (femoral 41um vs 21um; cup 50um vs 16um, p=0.05). As a function of size (46 and less = small), the <46mm group had a slightly shorter time to revision, 30 vs 38 months, p=0.04). Bone ingrowth ranged from 0 to 60% (Figure 1) and significantly less bone attachment was noted in both the smaller and larger components (p = 0.001). Other characteristics were similar in both groups. When wear-related failure modes (cup malposition, lysis, high ions) were compared, no differences between male and female or large vs small were found. The amount of cement in the femoral heads covered a wide range but femoral loosening or fracture rates were not different as a function of size or gender. Conclusion. This review of 248 revised HRAs from multiple surgeons, designs and modes of failure found no clear evidence that smaller HRA components were at higher risk of earlier failure or for any particular failure mode. The small components in this cohort were not more likely to have wear-related failures but of note, very few of these HRAs had implants with low coverage angles in the small sizes

The histopathology of periprosthetic tissues has been important to understanding the relationship between wear debris and arthroplasty outcome. In a landmark 1977paper, Willert and Semlitsch (1) used a semiquantitative rating to show that tissue reactions largely reflected the extent of particulate debris. Notably, small amounts of debris, including metal, could be eliminated without “overstraining the tissues” but excess debris led to deleterious changes. Currently, a plethora of terms is used to describe tissues from metal-on-metal (M-M) hips and corroded modular connections. We reviewed the evaluation and reporting of local tissue reactions over time, and asked if a dose response has been found between metal and tissue features, and how the use of more standardized terms and quantitative methodologies could reduce the current confusion in terminology. Methods. The PubMed database was searchedbetween 2000 and 2015 for papers using “metal sensitivity /allergy /hypersensitivity, Adverse Local Tissue Reaction (ALTR): osteolysis, metallosis, lymphocytic infiltration, Aseptic Lymphocytic Vasculitis-Associated Lesions (ALVAL), Adverse Reaction to Metal Debris (ARMD) or pseudotumor/ pseudotumour” as well as metal-on-metal / metal-metal AND hip arthroplasty/replacement. Reports lacking soft tissue histological analysis were excluded. Results. 131 articles describing M-M tissue histology were found. In earlier studies, the terms metal sensitivity / hypersensitivity /allergy implied or stated the potential for a Type IV delayed type hypersensitivity response as a reason for revision. More recently those terms have largely been replaced by broader terms such as ALTR, ALVAL and ARMD. ALVAL and metal hypersensitivity were often used interchangeably, both as failure modes and histological findings. Several histology scoring systems have been published but were only used in a limited number of studies. Correlations of histological features with metal levels or component wear were inconclusive, typically because of a high degree of variability. Interestingly, there were very few descriptions that concluded that the observed reactions were benign / normal or anticipated i.e. regardless of the histological features, extent of debris or failure mode, the histology was interpreted as showing an adverse reaction. Discussion. There is now an expanded set of terms to describe tissues but they lack clear definitions and typically do not use quantitative histological data to describe a wide range of periprosthetic reactions to metal. Lower limits of inflammation, necrosis or re-organization that represent a “normal” reaction to surgery and/or small amounts of wear debris are not clearly defined and are rarely discussed. The widespread adoption of the term “adverse” in the present tissue lexicon implies a cause and effect relationship between metal wear and corrosion products and histological features even though this has yet to be determined. The use of quantitative histological scores rather than subjective histological descriptions is imperative to improve the understanding and reporting of the range of periprosthetic reactions. In particular, a new lexicon that allows for a level of tissue reaction that is not misinterpreted as adverse is required

The October 2013 Hip & Pelvis Roundup. 360 . looks at: Young and impinging; Clothes, weather and femoral heads?; Go long, go cemented; Surgical repair of the abductors?; Aspirin for DVT prophylaxis?; Ceramic-on-polyethylene: a low-wear solution?; ALVAL and ASR™: the story continues….; Salvaging Legg-Calve-Perthes’ disease

Despite the increasing interest and subsequent published literature on hip resurfacing arthroplasty, little is known about the prevalence of its complications and in particular the less common modes of failure. The aim of this study was to identify the prevalence of failure of hip resurfacing arthroplasty and to analyse the reasons for it. From a multi-surgeon series (141 surgeons) of 5000 Birmingham hip resurfacings we have analysed the modes, prevalence, gender differences and times to failure of any hip requiring revision. To date 182 hips have been revised (3.6%). The most common cause for revision was a fracture of the neck of the femur (54 hips, prevalence 1.1%), followed by loosening of the acetabular component (32 hips, 0.6%), collapse of the femoral head/avascular necrosis (30 hips, 0.6%), loosening of the femoral component (19 hips, 0.4%), infection (17 hips, 0.3%), pain with aseptic lymphocytic vascular and associated lesions (ALVAL)/metallosis (15 hips, 0.3%), loosening of both components (five hips, 0.1%), dislocation (five hips, 0.1%) and malposition of the acetabular component (three hips, 0.1%). In two cases the cause of failure was unknown. Comparing men with women, we found the prevalence of revision to be significantly higher in women (women = 5.7%; men = 2.6%, p < 0.001). When analysing the individual modes of failure women had significantly more revisions for loosening of the acetabular component, dislocation, infection and pain/ALVAL/metallosis (p < 0.001, p = 0.004, p = 0.008, p = 0.01 respectively). The mean time to failure was 2.9 years (0.003 to 11.0) for all causes, with revision for fracture of the neck of the femur occurring earlier than other causes (mean 1.5 years, 0.02 to 11.0). There was a significantly shorter time to failure in men (mean 2.1 years, 0.4 to 8.7) compared with women (mean 3.6 years, 0.003 to 11.0) (p < 0.001)

Aims

This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection.

Metal-on-metal (MOM) hip arthroplasty, including resurfacing, has become the subject of recent research and debate. There is the perceived benefit of improved wear rates of bearing surfaces leading to superior durability and performance of these types of implant. An associated feature of MOM bearing surfaces is the generation of metal ions. These can have local and systemic cytotoxic effects. An immunoloigical response has been suggested, however, metal wear debris may cause direct damage to cellular DNA. Studies have shown that release of these ions is related to bearing diameter and component alignment. However, little is known about the relationship between metal ion levels and implant survivorship. The MHRA has published guidelines on the follow-up of patients with MOM implants including measurement of serum ion levels and cross sectional imaging. Between February 2001 and November 2009, 135 patients (164 hips) had MOM resurfacing arthroplasty at our institution. We report a retrospective analysis of the data generated by review of these patients. Of the 135 patients, 91 were identified for clinical review. Each patient had serum metal ion levels measured, plain AP radiographs of the pelvis examined and, in the presence of raised metal ions, a Metal Artefact Reduction Sequence (MARS) MRI performed. 27 patients (35 hips) had raised metal ion levels (Cobalt and Chromium). Patients with raised metal ion levels had a mean acetabular cup inclination of 52.7 degrees compared with a mean inclination of 48.6 degrees in patients with normal ion levels (p<0.05). MARS MRI in the raised ion group revealed 9 patients with appearances suggestive of ALVAL. A number of these patients had hip revision surgery with the remainder awaiting potential revision. These findings reflect current evidence suggesting a relationship between sub-optimal component position and raised metal ion levels and an increased rate of ALVAL

Introduction. Little is known about the relationship between head-neck corrosion and its effect on periprosthetic tissues and distant organs in the majority of patients hosting apparently well-functioning devices. We studied the degree and type of taper damage and the histopathologic response in periprosthetic tissue and distant organs. Methods. A total of 50 contemporary THRs (34 primary, 16 revision) retrieved postmortem from 40 patients after 0.4–26 years were studied. Forty-three femoral stems were CoCrMo and 7 were Ti6Al4V. In every case, a CoCrMo-alloy head articulated against a cementless polyethylene cup (19 XLPE and 31 UHMWPE). H&E and IHC sections of the joint pseudocapsules and liver were graded 1–4 for the intensity of various inflammatory cell infiltrates and tissue necrosis. The nature of the tissue response in the joint capsule, liver, spleen, kidneys and lymph nodes was assessed. Wear and corrosion products in the tissues were identified using SEM and EDS. Taper surfaces were graded for corrosion damage using modified Goldberg scoring and examined by SEM to determine the acting corrosion mode. Correlations between damage scores and the histologic variables were generated using the Spearman test. Results. No correlation was seen between taper damage scores and the macrophage response in the joint pseudocapsule. The distribution of corrosion scores for heads and femoral trunnions is shown in Figure 1. Moderate or severe corrosion of the head and/or trunnion was present in 9 hips (8 CoCr/CoCr and 1 CoCr/TiAlV). One patient with bilateral hips had local ALVAL-like lymphocyte-dominated tissue reactions (Figure 2) and mild focal lymphocytic infiltrates in the liver and kidneys (Figure 3). This was associated with severe intergranular corrosion of the CoCrMo trunnion and column damage on the head taper. Particle-laden macrophages in pseudocapsules were significantly correlated with liver macrophages (r=.382, p=0.012) and liver lymphocytes (r=.367, p=0.013). Pseudocapsule macrophage responses to metallic and/or polyethylene wear particles ranged widely from minimal to marked. Focal tissue necrosis was related to high concentrations of particulate wear debris. A minimal number of metallic particle-laden macrophages were also detected in the liver and spleen; and macrophage granulomas were present in para-aortic lymph nodes, especially in revision cases. DISCUSSION. The generation of metal ions and particulates at corroded CoCrMo heads and CoCrMo or Ti6Al4V trunnions was a significant contributor to the presence of perivascular lymphocytes within the joint pseudocapsule, with 1 patient showing a histologic pattern consistent with ALVAL. Patient factors and the rate of corrosion are among variables influencing whether an ALVAL-type reaction will develop and whether or not it will become symptomatic. Macrophages in the joint pseudocapsules were positively correlated with inflammatory cells in the liver. In this study, the intensity of inflammatory infiltrates in distant organs was mild. However, several cases of organ dysfunction have been reported in association with catastrophic wear of CoCrMo components. It continues to be essential to minimize the generation of metal ions and particulates and to improve strategies for identifying and managing patients exposed to high levels of degradation products. For any figures or tables, please contact the authors directly

Aims

Metal-on-metal hip resurfacing (MoM-HR) has seen decreased usage due to safety and longevity concerns. Joint registries have highlighted the risks in females, smaller hips, and hip dysplasia. This study aimed to identify if reported risk factors are linked to revision in a long-term follow-up of MoM-HR performed by a non-designer surgeon.

Increased modularity of total hip arthroplasty components has occurred, with theoretical advantages and disadvantages. Recent literature indicates the potential for elevated revision rates of modular neck systems and the potential for metallosis and ALVAL (Aseptic Lymphocyte dominated Vasculitis Associated Lesion) formation at the modular neck/stem site. Retrieval analysis of one modular neck implant design including SEM (Scanning Electron Microscopy) assessment was done and correlated to FEA (Finite Element Analysis) as well as clinical features of patient demographics, implant and laboratory analysis. Correlation of the consistent corrosion locations to FEA indicates that the material and design features of this system may result in a biomechanical reason for failure. The stem aspect of the modular neck/stem junction may be at particular risk

The dual mobility (DM) bearing concept was introduced to reduce the risk of dislocation in total hip arthroplasty (THA). Our aim was to evaluate the early outcomes following the utilisation of DM in primary and revision THA in our unit. Prospectively collected data on all patients undergoing a DM bearing at was reviewed between July 2012and December 2015. The primary outcome assessed was dislocation, with a secondary outcome revision for any reasons. All data was gathered from patient clinical records and the digital picture archiving and communication system (PACS). 30 primary THA were undertaken and 54 revision THAin the time period described. 11 of the procedures involved a proximal femoral endoprosthesis. The mean age in the primary setting was 65 and 73 in the revision population. The main indications for using DM bearing in the primary setting were; trauma (40%), residual dysplasia (40%) and malignancy (17%). There were no dislocations in the primary THA category. Indications in the revision THA cohort included 33% for aseptic loosening, 11% for instability, 18% for ALVAL reactions, 20% for infection, 18% for fracture. 1 out of the 54 revision THA had one large bearing dislocation requiring closed reduction. Subsequent analysis confirmed that implant alignment was satisfactory and this was a patient compliance issue due to mental health concerns. To date no patient in either cohort required revision surgery. Overall dislocation rate was 1.2%. Our early experience with DM bearings has been positive with no evidence of early failure or loosening. The dislocation rate overall has been low and matches the current large series in the literature

Aims

Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA).

We retrospectively reviewed the mid term outcome of 88 MoM THA in 84 patients and 21Hip Resurfacing using Recap Magnum bearing surface performed during 2006 – 2009. There were 41 males and 47 females in the THA group and 17 males and 4 females in the Hip Resurfacing group. All procedures were performed through a posterior approach. The average head size for the THR group was 46mm and the cup size was 52mm and the average head size for the resurfacing was 50mm and cup size was 56mm respectively. Median age for the THA group was 60 yrs. (28–73) and for the Resurfacing it was 51.5 yrs. (32–62). Average follow up was 76 months for the THA group and 78 months for the Resurfacing group. Average serum cobalt for the THA and the Resurfacing groups were 53.2nmol/l (119) and 30.85 and the Chromium levels were 82.44nmol/l(134.5) and 67.49 respectively. Eight MRI scans showed abnormal fluid collections suspicious of ARMD in the THA group and 2 showed fluid collection in the Resurfacing group. There were five revisions in the THA group with the tissue diagnosis of ALVAL. In all except one case a well fixed uncemented stem (Taperloc) was retained. In our series Recap Magnum on a Taperloc stem showed 94% survival at five years and therefore we continue to review the cases annually with serum cobalt chromium levels and MRI scans

Aims

A limited number of investigations with conflicting results have described perivascular lymphocytic infiltration (PVLI) in the setting of total knee arthroplasty (TKA). The purpose of this study was to determine if PVLI found in TKAs at the time of aseptic revision surgery was associated with worse clinical outcomes and survivorship.

Aims

The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate.

Purpose of the study. We reviewed one hundred and twenty patients who had primary total hip replacement using Corail/Pinnacle Metal on metal bearing surfaces between 2006 and 2009. We were interested in the metal ion levels of the whole cohort, the incidence of unexplained pain, pseudo tumour lesions (ALVAL) and early loosening and failure. We were particularly interested in the relationship of the acetabular cup position in relation to the pelvis and lumbar spine. Material and methods. We reviewed 120 charts and 104 patients in total. All patients had metal ion assays (cobalt and chromium). All patients had standardised radiographic evaluation using a special technique to assess acetabular cup position and the relationship to the pelvis and lumbar spine. Results. Ten patients had mild hip pain. This was not considered to be pathological pain related to the MOM articulation. None of the patients had any generalised symptoms of metal allergy as reported in the literature. We detected one patient with soft tissue fluid collections suggestive of an ALVAL lesion on ultrasound. The average cup inclination was 48 degrees with a range from 34 to 53 degrees. Conclusion. Our experience at 5 years with the Corail/Pinnacle Metal on Metal articulation has been acceptable. NO DISCLOSURES

Pain following total hip arthroplasty is a relatively rare event. Several series place the incidence of some degree of pain post THA at approximately 5%. A systematic approach to determining etiology will direct treatment. Hip pain can be categorised as:. Extrinsic to the Hip. –. Spine +/− radiculopathy. –. Vascular disease. –. Metabolic (Paget's). –. Malignancy. Intrinsic to the Hip. Intracapsular/Implant. Loosening. Sepsis. Prosthetic failure. Osteolysis. Instability. Thigh pain. Stem tip pain. Hypersensitivity/ALVAL. Extracapsular. Iliopsoas tendonitis. Snapping Hip. Trochanter problems (bursitis). Heterotopic ossification. A full history and appropriate physical exam will direct the clinician. The use of routine radiographs, blood tests, and special tests (i.e., blood metal ions, advanced imaging techniques) will be discussed I detail

Metal Bearings in Hip Arthroplasty – What Have We Learned?. Large metal on metal bearings have come back to hip arthroplasty the past five to ten years with great promise to minimize wear debris, eliminate osteolysis, reduce dislocations and improve range of motion. While some of these claims have proven to be true, new problems have surfaced that threaten the success of these devices. Metalosis, “pseudotumours” and ALVAL (aseptic lymphocytic vasculitis associated lesions) are appearing. These lesions produce pain that is difficult to confirm on routine exam and xray but eventually lead to early revision surgery. This paper will examine the advantages and complications of this hard bearing surface with a special look at complications, their prevention and management

Numerous studies have shown highly cross-linked polyethylene (XLPE) to be an extremely low wear bearing surface for total hip arthroplasty (THA) at intermediate term follow-up. Wear rates and the incidence of osteolysis for CoCr femoral heads on XLPE liners appears to be considerably less than what is observed for conventional polyethylene (PE). This has been demonstrated even in younger, more active patients. Nevertheless, polyethylene wear and associated osteolysis are still a concern, since the indications for THA have been expanded to include younger and more active patients. Both wear simulator and clinical data suggest that ceramic femoral heads can reduce bearing surface wear of conventional PE. There is, however, extremely limited evidence supporting any advantage of ceramic femoral heads over CoCr femoral heads with regards to bearing surface wear of XLPE. This is perhaps due to the relative difficulty in measuring the low wear rates of XLPE bearings in general, regardless of material composition of the femoral head. Although ceramic femoral heads are more scratch resistant and less susceptible to third body wear, their current clinical use to reduce wear of XLPE bearings is, in reality, based on the unproven assumption that use of ceramic femoral heads will have a similar effect on wear reduction as is seen with ceramic on conventional PE bearing couples. Nevertheless, the use of ceramic femoral heads has become common in younger, more active patients. Recently, corrosion at the head neck junction of modular THA (trunnionosis), has been determined to be the possible source of metal debris and metal ions associated with adverse local tissue reactions (ALTR or ARMD) in THA, including ALVAL and pseudotumors. There is general agreement that trunnionosis results from mechanically assisted crevice corrosion (fretting) of the modular junctions common to nearly all contemporary THA designs. Several design, material and patient factors have been implicated as contributors to this problem including larger diameter femoral heads (>36 mm), reduced femoral neck and taper geometry, flexural rigidity of the taper, and patient body weight and activity level. Data from our multicenter implant retrieval program has shown that corrosion at the head-neck junction of contemporary modular THAs may be reduced with use of ceramic femoral heads. The use of ceramic femoral heads also eliminates the potential for release of cobalt and chromium ions from the taper junctions of titanium alloy stems. In younger patients, the long term effects of cobalt ions released from corrosion at the modular neck junction are still unknown. Although the surgeon's selection of a ceramic femoral head in combination with a XLPE acetabular liner is likely based on the desire to minimise PE wear, the impact of femoral head composition on taper neck corrosion and ALTR is perhaps more of a concern in 2015. Until the problem of taper neck corrosion is more thoroughly understood and effectively addressed by implant manufacturers, the use of ceramic femoral heads in THA should be considered in the younger or more active patient. The increased cost of ceramic femoral heads creates a dilemma in defining who is “young” enough and “active” enough to be considered an appropriate candidate for a ceramic femoral head in our current environment of bundled care payments, value based purchasing and concern about providing cost-effective health care to our patients

Hip resurfacing using metal-on-metal bearings has a number of purported advantages over traditional total hip replacement in the young, active patient. Males in particular can benefit from the bone preservation, stability, and higher activity levels seen with this procedure. As more is learned about the factors affecting long-term outcome of hip resurfacing, component position has emerged as one major predictor of success. Given a well-selected patient, and a well-designed device, acetabular positioning is perhaps the most important determinant of long-term survivorship in hip resurfacing. One feature of resurfacing socket design which has not been widely disseminated is the sub-hemispheric arc of the bearing surface. While the outer circumference of the socket represents a complete hemisphere, and radiographic evaluation may assume that the apparent socket angle is satisfactory, the actual bearing is less than a hemisphere, so that the true abduction of the bearing is considerably more vertical. This important fact leads to excessive bearing inclination, edge loading, and all that follows, including runaway wear, metallosis, ALVAL, and pseudotumors. Inadequate socket anteversion can expose the psoas tendon to abrasion and tendonitis. Too much acetabular anteversion, especially when combined with increased femoral neck anteversion, can result in an overall decrease in bearing contact area, and excessive wear. Femoral component positioning is critical in the prevention of femoral neck fractures, which are a chief cause of early failure. Varus placement increases the tensile stresses on the superior femoral neck. Excessive valgus threatens notching. Both increase femoral neck fractures. Sufficient malposition will ultimately result in edge loading. Edge wear is incompatible with fluid film lubrication, the key to longevity of these bearings

As part of a prospective RSA study into a new design of short-stem, trabecular metal, Co-Cr femoral components with modular necks and . metal on polyethylene articulation. , three patients presented with almost identical symptoms of pain and a large avascular mass within the operated hip. All three cases came to exploration and similar findings of a solid pseudotumour within the hip joint were found in all thee cases. Infection was not present. All cases were submitted to histology and reviewed by a pathologist with specific interest in tissue reactions to foreign materials. All three cases showed histological features classical of published descriptions of ALVAL (Aseptic Lymphocyte-dominated Vasculitis Associated Lesion). A consistent finding was fretting corrosion of the neck-stem junction. These cases demonstrate that Co and Cr ions can provoke adverse tissue reactions even in the absence of metal/metal articulations. This has design implications for all modular Co-Cr necks. The stem used in this study has been voluntarily withdrawn from the Australian market but is still being implanted in Europe. We make recommendations that modular trunnion-style Co-Cr necks not be used and alternative materials and design solutions be sought

Introduction. Metal on metal hip arthroplasty continues to be controversial. Emerging evidence suggests that there are multiple modes of failure, and that the results of revision surgery are influenced by host and implant factors. Methods. This study compares a single surgeon series of hip resurfacings (Birmingham Hip Resurfacing {BHR}) and large diameter metal on metal total hip replacements (LDMOMTHR). Primary outcome measures included survival rates, failure secondary to histologically identified Adverse Reaction to Metal Debris (ARMD), and patient reported outcome measures (Oxford Hip Score {OHS}) following revision. Between 1999 and 2005, 458 BHR and 175 LDMOMTHR were performed. At latest review 43 BHR's (9.4%) and 28 LDMOMTHR's (14%) have been revised. Results. Failure secondary to ARMD was significantly greater in LDMOMTHR compared to BHR failures (89% and 16% respectively). Histology demonstrated a higher Aseptic Lymphocytic Vascular and Associated Lesions (ALVAL) score in the LDMOMTHR failures than the BHR failures (8.6 LDMOMTHR, 6.3 BHR). Patient reported outcomes were better following revision for failed BHR compared to LDMOMTHR. There was no difference between the revision cohorts for cup inclination, metal ion levels and gender. Failure of the BHR has predominantly been due to those causes unique to resurfacing such as avascular necrosis and fracture. In our series, aggressive ALVAL was unusual and clinical outcome following revision was superior compared to LDMOMTHR failures. The likely mechanisms that are responsible for the differences in outcome and the clinical implications will be discussed

Aims

Dual mobility implants in total hip arthroplasty are designed to increase the functional head size, thus decreasing the potential for dislocation. Modular dual mobility (MDM) implants incorporate a metal liner (e.g. cobalt-chromium alloy) in a metal shell (e.g. titanium alloy), raising concern for mechanically assisted crevice corrosion at the modular liner-shell connection. We sought to examine fretting and corrosion on MDM liners, to analyze the corrosion products, and to examine histologically the periprosthetic tissues.

The metal-on-metal total hip resurfacing arthroplasty is a good solution for the younger patient with osteoarthritis of the hip. It is effective in pain resolution and provides a good function. Our study of 300 BHR arthroplasties with a follow-up of 2 to 7 year shows good results in a young and active population. With an overall survival of 96.7% we obtained similar results to those of the design centre. The overall postoperative HHS score of 95.78 +/− 12.63 is in line with other studies. We noticed a similar increase in HHS in female patients and male patients. Even in the HOOS scores there was no significant difference between both groups. This is an important finding for the surgeon as well as the patients. Looking at the VAS scores for satisfaction or reoperation we could state that the high expectations of this population have been fulfilled. With have an acceptable revision rate of 2.42% the patients undergoing a revision were of a simular mean age than those in the overall group. Five of them are female, two are male. Since there were twice as many female as male patients there is little difference in revision percentage between both groups. There was 1 patient with a bilateral revision because of ALVAL (aseptic lymphocytic vasculitis associated lesion). Although femoral neck fractures are a known complication, there where none in our series. Patients are able to lead an active life and perform sports. The postoperative benefits are equal in men and women. The satisfaction rate confirms that we are able to meet the expectations in this high demand group

Hip resurfacing arthroplasty is an established and effective intervention for osteoarthritis of the hip in the young active patient, relying on the principle of femoral bone-stock preservation. A recognised mode of failure is neck thinning leading to radiological evidence of neck collapse and clinical failure. We report on a series of these slow-neck-failure patients and highlight the increased incidence of this phenomenon in post-menopausal female patients. This is a single operator, single implant series; 172 cases were identified from databases at our institution. 76 were female, mean (SD) age 52 (7) years. 96 were male, mean (SD) age 51(12) years. 15 (8.7%) patients required revision. 12 (80%) were female, 9 (75%) of these were due to slow neck failure. In the men one patient developed ALVAL requiring removal of his bilateral hip resurfacings, the other failure mode was early femoral neck failure. Mean time to failure was 6 months in men and 37 months in women. This difference in failure rates is also seen in the NJR figures. This review confirms the relatively high incidence of premature failure in post-menopausal females. NICE guidance in 2003, currently under review, stated that resurfacing is indicated in male patients up to 65 and female patients up to 60. As a result of this study we are currently advising post-menopausal patients that this risk of early failure may make total hip replacement a preferable option to resurfacing arthroplasty

Early failure of metal-on-metal (MoM) total hip replacements (THR) is now well established. We review 93 consecutive patients with CPT¯ stems MoM THR. Our series demonstrates a new mechanism of failure, which may be implant combination specific. Between January 2005 and June 2009, 93 consecutive MoM total hip replacements were preformed using CPT stems by 3 surgeons at our unit. 73 CPT¯ stems, Metasul¯ Large Diameter Heads (LDH) with Durom¯ acetabulae and 20 CPT¯ stems, Metasul¯ 28mm diameter heads in Allofit¯ shells (zimmer). Clinical outcomes were collected prospectively before surgery, at 3 months, 1 year, 2 years, 3 years, and at 5 years post surgery. Revision for any cause was taken as the primary endpoint and the roentgenograms and explanted prostheses were analyzed for failure patterns. In the LDH/Durom¯ group a total of 13 (18%) patients required revision (figs. 1) at a median of 35 months (range 6-44). 6 (8%) for periprosthetic fracture. All 6 periprostethic fractures were associated with minimal or no trauma and all had ALVAL identified histologically. To date there have been no failures in the CPT¯/28mm head Allofit¯ group. Several failures demonstrated bone loss in Gruen zones 8 ± 9 ± 10 (fig. 2). We demonstrate an unacceptably high rate of failure in CPT¯ MoM LDH hip replacements, with a high failure secondary to periprosthetic fracture and postulate a mechanism associated with local toxicity to metal ions. We strongly advise against this combination of prosthesis

Introduction. We conducted independent wear analysis of retrieved metal on metal (MoM) hip components from around the world. All patients with resurfaced hips who developed adverse reactions to metal debris (ARMD) were found to have increased wear of the bearing surfaces. This was untrue in patients with large diameter (?36mm) MoM total hip replacements. This led us to search for other factors leading to ARMD. Methods. MoM THR explants retrieved from 78 patients suffering ARMD underwent full volumetric wear analysis of bearing surface and taper-junctions using coordinate measuring machine. Scanning electron microscopy (SEM) used to characterise material composition of specific areas. Results. 34 MoM THRs were found to have relatively low bearing surface wear (< 3mm. 3. /year). In each of these cases, material loss up to 60 microns wear depth was identified on the internal taper-junctions of femoral components. However, volumetric loss was rarely >5mm. 3. Similarly only 65% of metal ion levels of these patients were found to be greater than the MHRA guidance figure (7µg/L). Patterns of material loss at the tapers were consistent with antero-posterior force splaying open the taper-junction. This characteristic pattern was identified in number of commercially available devices (titanium and cobalt chromium stems). Soft tissue lesions were severe in patients found to have taper damage. Histology confirmed severe ALVAL with lymphoid neogenesis in majority cases, suggesting that wear debris from taper junctions may have greater potential to stimulate adverse immune response. Discussion. The results suggest that forces transmitted from large diameter hard-on-hard bearing surfaces are sufficient to cause mechanical damage to modular junctions with secondary localised corrosion. We urge caution in the use of these designs and recommend a re-evaluation of the stem head interface

Background. Previous studies have suggested that the modular junction of metal on metal (MoM) total hip replacements (THR) is an important source of metallic debris. Methods. We carried out a prospective study using custom techniques to analyse one of the largest collections of failed contemporary MoM devices in the world. All explants from patients who had suffered adverse reactions to metal debris (ARMD) were included in this study. These explants included: 82 36mm THRs, and 147 resurfacing head THRs and 140 resurfacing arthroplasties from several manufactures. Volumetric wear analysis of the bearing surfaces and taper junctions was carried out using a coordinate measuring machine. The relationships between total metallic loss and metal ion concentrations and the macroscopic and histological tissue appearance of THR patients were compared to those in resurfacing patients. Mann Whitney test for non-parametric data was used to assess significant differences between groups. Results. Resurfacing explants retrieved from patients who had suffered ARMD were found to have significantly higher median rates of volumetric wear than the THRs (10.16 versus 2.25mm. 3. /yr (p < 0.001)). Total volumetric material loss from taper junctions ranged from 0.01 to 21.55mm. 3. When volumetric taper wear was combined with bearing surface wear in the THR patients this total rate of material loss was still significantly less than in the resurfacing patients 2.52 versus 10.16mm. 3. /yr (p < 0.001)). Despite this, macroscopic tissue destruction and extent of ALVAL infiltration was found to be significantly greater in the THR patients. Conclusion. Taper debris appears to more readily stimulate a destructive immune cascade than debris from primary bearing surfaces. This cascade can culminate in catastrophic tissue necrosis when blood metal ion concentrations appear normal. MHRA guidance should distinguish clearly between MOM THRs and resurfacings

This report documents the clinical and histological findings, the operative management and the explant analyses of patients with early aseptic failure of large metal-on-metal (MonM) bearing joints. Three hundred and fifty patients have been implanted with the ASR bearing surface (resurfacing or a modular THR) by a single surgeon at an independent centre since 2004. Six patients (all female) have been revised secondary to aseptic failure. All complained of severe groin pain exacerbated by straight leg raise and routine investigations were unable to establish a cause. Large amounts of sterile, highly viscous green fluid were aspirated from the hip joints in each case. Gross swelling of the pseudocapsule and a similar green fluid surrounding the implants were found at revision surgery. Histological examination of periprosthetic tissue samples showed changes consistent with ALVAL/metallosis, and analysis of the fluid revealed dense numbers of inflammatory cells. Symptoms in patients revised to ceramic-on-ceramic bearings improved post operatively. This was not the case with those reimplanted with MoM joints. Data from a subset of 76 patients (all unilateral resurfacings) showed that malaligned cups (anteverted > 20° +/− inclination angle > 45°) were associated with significantly higher whole blood metal ion levels than cups positioned within this range. All the patients with early aseptic failure had malaligned cups. Independent explant analysis revealed significant increases in the surface roughness values of the articular surfaces. Our results suggest that some patients develop a significant inflammatory reaction to metal implants. This may be due to high levels of metal debris around the implant as a result of accelerated wear. Poor component alignment was found in all our patients with early aseptic failure