Which factors influence the rate of failure following metal-on-metal hip arthroplasty revision surgery performed for adverse reactions to metal debris? AN ANALYSIS FROM THE NATIONAL JOINT REGISTRY FOR ENGLAND AND WALES

Aims To determine the outcomes following revision surgery of metal-on-metal hip arthroplasties (MoMHA) performed for adverse reactions to metal debris (ARMD), and to identify factors predictive of re-revision. Patients and Methods We performed a retrospective observational study using National Joint Registry (NJR) data on 2535 MoMHAs undergoing revision surgery for ARMD between 2008 and 2014. The outcomes studied following revision were intra-operative complications, mortality and rerevision surgery. Predictors of re-revision were identified using competing-risk regression modelling. Results Intra-operative complications occurred in 40 revisions (1.6%). The cumulative five-year patient survival rate was 95.9% (95% confidence intervals (CI) 92.3 to 97.8). Re-revision surgery was performed in 192 hips (7.6%). The cumulative five-year implant survival rate was 89.5% (95% CI 87.3 to 91.3). Predictors of re-revision were high body mass index at revision (subhazard ratio (SHR) 1.06 per kg/m2 increase, 95% CI 1.02 to 1.09), modular component only revisions (head and liner with or without taper adapter; SHR 2.01, 95% CI 1.19 to 3.38), ceramic-on-ceramic revision bearings (SHR 1.86, 95% CI 1.23 to 2.80), and acetabular bone grafting (SHR 2.10, 95% CI 1.43 to 3.07). These four factors remained predictive of re-revision when the missing data were imputed. Conclusion The short-term risk of re-revision following MoMHA revision surgery performed for ARMD was comparable with that reported in the NJR following all-cause non-MoMHA revision surgery. However, the factors predictive of re-revision included those which could be modified by the surgeon, suggesting that rates of failure following ARMD revision may be reduced further

Outcomes After Metal-on-metal Hip Revision Surgery Depend on the Reason for Failure: A Propensity Score-matched Study

Background Metal-on-metal hip replacement (MoMHR) revision surgery for adverse reactions to metal debris (ARMD) has been associated with an increased risk of early complications and reoperation and inferior patient-reported outcome scores compared with non-ARMD revisions. As a result, early revision specifically for ARMD with adoption of a lower surgical threshold has been widely recommended with the goal of improving the subsequent prognosis after ARMD revisions. However, no large cohorts have compared the risk of complications and reoperation after MoMHR revision surgery for ARMD (an unanticipated revision indication) with those after non-ARMD revisions (which represent conventional modes of arthroplasty revision). Questions/purposes (1) Does the risk of intraoperative complications differ between MoMHRs revised for ARMD compared with non-ARMD indications? (2) Do mortality rates differ after MoMHRs revised for ARMD compared with non-ARMD indications? (3) Do rerevision rates differ after MoMHRs revised for ARMD compared with non-ARMD indications? (4) How do implant survival rates differ after MoMHR revision when performed for specific non-ARMD indications compared with ARMD? Methods This retrospective observational study involved all patients undergoing MoMHR from the National Joint Registry (NJR) for England and Wales subsequently revised for any indication between 2008 and 2014. The NJR achieves high levels of patient consent (93%) and linked procedures (ability to link serial procedures performed on the same patient and hip; 95%). Furthermore, recent validation studies have demonstrated that when revision procedures have been captured within the NJR, the data completion and accuracy were excellent. Revisions for ARMD and non-ARMD indications were matched one to one for multiple potential confounding factors using propensity scores. The propensity score summarizes the many patient and surgical factors that were used in the matching process (including sex, age, type of primary arthroplasty, time to revision surgery, and details about the revision procedure performed such as the approach, specific components revised, femoral head size, bearing surface, and use of bone graft) using one single score for each revised hip. The patient and surgical factors within the ARMD and non-ARMD groups subsequently became much more balanced once the groups had been matched based on the propensity scores. The matched cohort included 2576 MoMHR revisions with each study group including 1288 revisions (mean followup of 3 years for both groups; range, 1-7 years). Intraoperative complications, mortality, and rerevision surgery were compared between matched groups using univariable regression analyses. Implant survival rates in the non-ARMD group were calculated for each specific revision indication with each individual non-ARMD indication subsequently compared with the implant survival rate in the ARMD group using Cox regression analyses. Results There was no difference between the ARMD and non-ARMD MoMHR revisions in terms of intraoperative complications (odds ratio, 0.97; 95% confidence interval [CI], 0.59-1.59; p = 0.900). Mortality rates were lower after ARMD revision compared with non-ARMD revision (hazard ratio [HR], 0.43; CI, 0.21-0.87; p = 0.019); however, there was no difference when revisions performed for infection were excluded from the non-ARMD indication group (HR, 0.69; CI, 0.35-1.37; p = 0.287). Rerevision rates were lower after ARMD revision compared with non-ARMD revision (HR, 0.52; CI, 0.36-0.75; p < 0.001); this difference persisted even after removing revisions performed for infection (HR, 0.59; CI, 0.40-0.89; p = 0.011). Revisions for infection (5-year survivorship = 81%; CI, 55%-93%; p = 0.003) and dislocation/subluxation (5-year survivorship = 82%; CI, 69%-90%; p < 0.001) had the lowest implant survival rates when compared with revisions for ARMD (5-year survivorship = 94%; CI, 92%-96%). Conclusions Contrary to previous observations, MoMHRs revised for ARMD have approximately half the risk of rerevision compared with non-ARMD revisions. We suspect worldwide regulatory authorities have positively influenced rerevision rates after ARMD revision by recommending that surgeons exercise a lower revision threshold and that such revisions are now being performed at an earlier stage. The high risk of rerevision after MoMHR revision for infection and dislocation is concerning. Infected MoMHR revisions were responsible for the increased mortality risk observed after non-ARMD revision, which parallels findings in non-MoMHR revisions for infection. Level of Evidence Level III, therapeutic study

Revision surgery of metal-on-metal hip arthroplasties for adverse reactions to metal debris

Background and purpose The initial outcomes following metal-on-metal hip arthroplasty (MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD) were poor. Furthermore, robust thresholds for performing ARMD revision are lacking. This article is the second of 2. The first article considered the various investigative modalities used during MoMHA patient surveillance (Matharu et al. 2018aMatharu G S, Judge A, Eskelinen A, Murray D W, Pandit H G. What is appropriate surveillance for metal-on-metal hip arthroplasty patients? A clinical update. Acta Orthop 2018a; 89 (1): 29–39.[Taylor & Francis Online], [Web of Science ®], [Google Scholar]). The present article aims to provide a clinical update regarding ARMD revision surgery in MoMHA patients (hip resurfacing and large-diameter MoM total hip arthroplasty), with specific focus on the threshold for performing ARMD revision, the surgical strategy, and the outcomes following revision. Results and interpretation The outcomes following ARMD revision surgery appear to have improved with time for several reasons, among them the introduction of regular patient surveillance and lowering of the threshold for performing revision. Furthermore, registry data suggest that outcomes following ARMD revision are influenced by modifiable factors (type of revision procedure and bearing surface implanted), meaning surgeons could potentially reduce failure rates. However, additional large multi-center studies are needed to develop robust thresholds for performing ARMD revision surgery, which will guide surgeons’ treatment of MoMHA patients. The long-term systemic effects of metal ion exposure in patients with these implants must also be investigated, which will help establish whether there are any systemic reasons to recommend revision of MoMHA

The effect of smoking on outcomes following primary total hip and knee arthroplasty: a population-based cohort study of 117,024 patients

Background and purpose — Smoking is a modifiable risk factor that may adversely affect postoperative outcomes. Healthcare providers are increasingly denying smokers access to total hip and knee arthroplasty (THA and TKA) until they stop smoking. Evidence supporting this is unclear. We assessed the effect of smoking on outcomes following arthroplasty. Patients and methods — We identified THAs and TKAs from the Clinical Practice Research Datalink, which were linked with datasets from Hospital Episode Statistics and the Office for National Statistics to identify outcomes. The effect of smoking on postoperative outcomes (complications, medications, revision, mortality, patient-reported outcome measures [PROMs]) was assessed using adjusted regression models. Results — We studied 60,812 THAs and 56,212 TKAs (11% smokers, 33% ex-smokers, 57% non-smokers). Following THA, smokers had an increased risk of lower respiratory tract infection (LRTI) and myocardial infarction compared with non-smokers and ex-smokers. Following TKA, smokers had an increased risk of LRTI compared with non-smokers. Compared with non-smokers (THA relative risk ratio [RRR] = 0.65; 95% CI = 0.61–0.69; TKA RRR = 0.82; CI = 0.78–0.86) and ex-smokers (THR RRR = 0.90; CI = 0.84–0.95), smokers had increased opioid usage 1-year postoperatively. Similar patterns were observed for weak opioids, paracetamol, and gabapentinoids. 1-year mortality rates were higher in smokers compared with non-smokers (THA hazard ratio [HR] = 0.37, CI = 0.29–0.49; TKA HR = 0.52, CI = 0.34–0.81) and ex-smokers (THA HR = 0.53, CI = 0.40–0.70). Long-term revision rates were not increased in smokers. Smokers had improvement in PROMs compared with preoperatively, with no clinically important difference in postoperative PROMs between smokers, non-smokers, and ex-smokers. Interpretation — Smoking is associated with more medical complications, higher analgesia usage, and increased mortality following arthroplasty. Most adverse outcomes were reduced in ex-smokers, therefore smoking cessation should be encouraged before arthroplasty

No Threshold Exists for Recommending Revision Surgery in Metal-on-Metal Hip Arthroplasty Patients With Adverse Reactions to Metal Debris: A Retrospective Cohort Study of 346 Revisions

Background Surgeons currently have difficulty when managing metal-on-metal hip arthroplasty (MoMHA) patients with adverse reactions to metal debris (ARMD). This stems from a lack of evidence, which is emphasized by the variability in the recommendations proposed by different worldwide regulatory authorities for considering MoMHA revision surgery. We investigated predictors of poor outcomes following MoMHA revision surgery performed for ARMD to help inform the revision threshold and type of reconstruction. Methods We retrospectively studied 346 MoMHA revisions for ARMD performed at 2 European centers. Preoperative (metal ions/imaging) and intraoperative (findings, components removed/implanted) factors were used to predict poor outcomes. Poor outcomes were postoperative complications (including re-revision), 90-day mortality, and poor Oxford Hip Score. Results Poor outcomes occurred in 38.5%. Shorter time (under 4 years) to revision surgery was the only preoperative predictor of poor outcomes (odds ratio [OR] = 2.12, confidence interval [CI] = 1.00-4.46). Prerevision metal ions and imaging did not influence outcomes. Single-component revisions (vs all-component revisions) increased the risk of poor outcomes (OR = 2.99, CI = 1.50-5.97). Intraoperative modifiable factors reducing the risk of poor outcomes included the posterior approach (OR = 0.22, CI = 0.10-0.49), revision head sizes ≥36 mm (vs <36 mm: OR = 0.37, CI = 0.18-0.77), ceramic-on-polyethylene revision bearings (OR vs ceramic-on-ceramic = 0.30, CI = 0.14-0.66), and metal-on-polyethylene revision bearings (OR vs ceramic-on-ceramic = 0.37, CI = 0.17-0.83). Conclusion No threshold exists for recommending revision in MoMHA patients with ARMD. However postrevision outcomes were surgeon modifiable. Optimal outcomes may be achieved if surgeons use the posterior approach, revise all MoMHA components, and use ≥36 mm ceramic-on-polyethylene or metal-on-polyethylene articulations

Adverse reactions to metal debris occur with all types of hip replacement not just metal-on-metal hips: a retrospective observational study of 3340 revisions for adverse reactions to metal debris from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man.

BACKGROUND: Adverse reactions to metal debris (ARMD) have resulted in the high short-term failure rates observed with metal-on-metal hip replacements. ARMD has recently been reported in non-metal-on-metal total hip replacements (non-MoM THRs) in a number of small cohort studies. However the true magnitude of this complication in non-MoM THRs remains unknown. We used a nationwide database to determine the risk of ARMD revision in all non-MoM THRs, and compared patient and surgical factors associated with ARMD revision between non-MoM and MoM hips. METHODS: We performed a retrospective observational study using data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All primary hip replacements undergoing revision surgery for ARMD were included (n = 3,340). ARMD revision risk in non-MoM THRs was compared between different commonly implanted bearing surfaces and femoral head sizes (Chi-squared test). Differences in patient and surgical factors between non-MoM hips and MoM hips revised for ARMD were also analysed (Chi-squared test and unpaired t-test). RESULTS: Of all ARMD revisions, 7.5% (n = 249) had non-MoM bearing surfaces. The relative risk of ARMD revision was 2.35 times (95% CI 1.76-3.11) higher in ceramic-on-ceramic bearings compared with hard-on-soft bearings (0.055 vs. 0.024%; p < 0.001), and 2.80 times (95% CI 1.74-4.36) higher in 36 mm metal-on-polyethylene bearings compared to 28 mm and 32 mm metal-on-polyethylene bearings (0.058 vs. 0.021%; p < 0.001). ARMD revisions were performed earlier in non-MoM hips compared to MoM hips (mean 3.6-years vs. 5.6-years; p < 0.0001). Non-MoM hips had more abnormal findings at revision (63.1 vs. 35.7%; p < 0.001), and more intra-operative adverse events (6.4 vs. 1.6%; p < 0.001) compared to MoM hips. CONCLUSIONS: Although the overall risk of ARMD revision surgery in non-MoM THRs appears low, this risk is increasing, and is significantly higher in ceramic-on-ceramic THRs and 36 mm metal-on-polyethylene THRs. ARMD may therefore represent a significant clinical problem in non-MoM THRs

Quantifying the natural history of post-radical prostatectomy incontinence using objective pad test data

BACKGROUND: Urinary incontinence (UI) following radical prostatectomy is a well-recognized risk of the surgery. In most patients post-operative UI improves over time. To date, there is limited objective, quantitative data on the natural history of the resolution of post-prostatectomy UI. The purpose of this study was to define the natural history of post radical prostatectomy incontinence using an objective quantitative tool, the 1-hour standard pad test. METHODS: 203 consecutive patients underwent radical prostatectomy by a single surgeon between 03/98 & 08/03. A standardized 1-hour pad test was administered at subsequent postoperative clinic visits. The gram weight of urine loss was recorded and subdivided into four groups defined according to the grams of urine loss: minimal (<1 g), mild (>1, <10 g), moderate (10–50 g) and severe (>50 g). Patients were evaluated: at 2 weeks (catheter removal), 6 weeks, 18 weeks, 30 weeks, 42 weeks and 54 weeks. The data set was analyzed for average urine loss as well as grams of urine loss at each time point, the percentage of patients and the distribution of patients in each category. RESULTS: Mean follow up was 118 weeks. The majority of patients experienced incontinence immediately after catheter removal at 2 weeks that gradually improved with time. While continued improvement was noted to 1 year, most patients who achieved continence did so by 18 weeks post-op. CONCLUSION: While the majority of patients experience mild to severe UI immediately following catheter removal, there is a rapid decrease in leaked weight during the first 18 weeks following RRP. Patients continue to improve out to 1 year with greater than 90% having minimal leakage by International Continence Society criteria

Activation of synovial fibroblasts from patients at revision of their metal-on-metal total hip arthroplasty

BACKGROUND: The toxicity of released metallic particles generated in metal-on-metal (MoM) total hip arthroplasty (THA) using cobalt chromium (CoCr) has raised concerns regarding their safety amongst both surgeons and the public. Soft tissue changes such as pseudotumours and metallosis have been widely observed following the use of these implants, which release metallic by-products due to both wear and corrosion. Although activated fibroblasts, the dominant cell type in soft tissues, have been linked to many diseases, the role of synovial fibroblasts in the adverse reactions caused by CoCr implants remains unknown. To investigate the influence of implants manufactured from CoCr, the periprosthetic synovial tissues and synovial fibroblasts from patients with failed MoM THA, undergoing a revision operation, were analysed and compared with samples from patients undergoing a primary hip replacement, in order to elucidate histological and cellular changes. RESULTS: Periprosthetic tissue from patients with MoM implants was characterized by marked fibrotic changes, notably an increase in collagen content from less than 20% to 45-55%, an increase in α-smooth muscle actin positive cells from 4 to 9% as well as immune cells infiltration. Primary cell culture results demonstrated that MoM synovial fibroblasts have a decreased apoptosis rate from 14 to 6% compared to control synovial fibroblasts. In addition, synovial fibroblasts from MoM patients retained higher contractility and increased responsiveness to chemotaxis in matrix contraction. Their mechanical properties at a single cell level increased as observed by a 60% increase in contraction force and higher cell stiffness (3.3 kPa in MoM vs 2.18 kPa in control), as measured by traction force microscopy and atomic force microscopy. Further, fibroblasts from MoM patients promoted immune cell invasion by secreting monocyte chemoattractant protein 1 (MCP-1, CCL2) and induced monocyte differentiation, which could also be associated with excess accumulation of synovial macrophages. CONCLUSION: Synovial fibroblasts exposed in vivo to MoM THA implants that release CoCr wear debris displayed dramatic phenotypic alteration and functional changes. These findings unravelled an unexpected effect of the CoCr alloy and demonstrated an important role of synovial fibroblasts in the undesired tissue reactions caused by MoM THAs

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue

Background The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination. Methods The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles. Results All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis. Conclusions The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies