Predictive Factors for Revision and Survivorship Analysis of a Prevalent 36-mm Metal-on-Metal Total Hip Replacement System: A Large Single-Center Retrospective Cohort Study.

BACKGROUND: To our knowledge, this is the largest single-center cohort of the 36-mm Corail-Pinnacle metal-on-metal total hip replacements system, aiming to determine 10-year survivorship and identify predictors of revision. We further assessed year of implantation given reports of manufacturing variations affecting shells made after 2006 predisposing these components to increasing wear. METHODS: All Corail-Pinnacle 36-mm metal-on-metal hips implanted in a single center (2005-2012). The effect of patient and implant-related variables, and year of implantation on revision risk was assessed using Kaplan-Meier, Cox regression, and interrupted time series analysis. RESULTS: In total, 1212 metal-on-metal total hip replacements were implanted with a 10-year survival rate of 83.4% (95% confidence interval [CI] = 81.3-85.5). Mean follow-up duration was 7.3 years with 61% of patients reaching a minimum of 7 years of follow-up. One hundred nineteen patients required revision surgery (9.8%). Univariate analysis identified female gender (hazard ratio [HR] = 1.608, CI = 1.093-2.364, P = .016), age at implantation (HR = 0.982, CI = 0.968-0.997, P = .019), smaller 50-mm to 54-mm cup diameter (HR = 1.527, CI = 1.026-2.274, P = .037), and high-offset stems (HR = 2.573, CI = 1.619-4.089, P < .001) as predictors of revision. Multivariate modeling confirmed female gender and high-offset stems as significant predictors of revision. For components implanted after 2007, the number of revisions showed no statistically significant step increase compared to pre-2007 implantation. CONCLUSION: We observed a high 10-year failure rate (16.6%) with this implant, mostly due to adverse reaction to metal debris. Female gender and high femoral offset stems were significant predictors for all-cause revision. Year of implantation was not significantly associated with an increasing number of revisions from 2007 onwards, although further studies to validate the impact of manufacturing discrepancies are recommended.

An Analysis of Reported Cases of Fracture of the Universal Exeter Femoral Stem Prosthesis.

BACKGROUND: Between 1991 and 2008, approximately 80 cases of fracture (neck or stem) have been reported. This study aimed at determining factors predisposing to implant fracture. METHODS: Clinical, surgical, radiological, and retrieval data were collated. Risk factors associated with fracture were categorized to patient related (weight and activity levels), surgical related (poor medial support, component size, and placement), and anatomic/implant related (head size/offset). RESULTS: Data was available on 60 patients (32 stem and 28 neck fractures). Mean patient age at fracture was similar for both neck and stem fractures (69 years, 67 years, respectively). Also, 77% neck and 52% stem fractures occurred in men. Mean weight was 107 kg in neck and 96.5 kg in stem fractures with 68% neck and 38% stem fractures either obese or morbidly obese. Mean time to fracture was 78 months (range, 36-144 months) for neck and 76 months (range, 2-155 months) for stem fractures. 44#2 and 44#3 were the most common sizes associated with neck fractures. Stem fractures occurred more commonly (84%) in the smaller sizes (35.5 to 44#1). Elongated femoral heads were used in 69% neck and 14% stem fractures. CONCLUSION: Neck fractures were most commonly associated with patient-related (increased weight and activity) and implant-related (use of an elongated femoral head) factors. Stem fractures were most commonly associated with correctable surgical-related causes, predominantly secondary to stem undersizing or inadequate medial support (84%).

Femoral revision in hip resurfacing compared with large-bearing metal-on-metal hip arthroplasty.

It has been suggested that revision of the femoral component of hip resurfacing after femoral failure would be straightforward and have an outcome comparable to primary total hip arthroplasty (THA). We have compared the outcome of femoral side-only revision resurfacings to the results of primary modular large-bearing metal-on-metal THA. Fourteen consecutive patients underwent revision surgery of the failed femoral component, to a cemented tapered stem (CPT, Zimmer, Warsaw, Indiana) with a large modular metal head (Smith and Nephew Orthopaedics Ltd, Memphis, Tennessee, or Adept, Finsbury Orthopaedics, Surrey, England). The acetabular component was found to be well fixed, well orientated, and was left in situ. The 14 matched patients in the primary THA group received the same components. At a mean follow-up of 49 months (range, 30-60 months), clinical outcome measured using the Oxford and Harris Hip Scores showed no significant difference (P = .11, P = .45, respectively). Operative time and blood loss were comparable for both groups. We conclude that revision of the failed femoral resurfacing component gives excellent results.

Indications for early hip revision surgery in the UK--a re-analysis of NJR data.

This study determined the rate and indication for revision between cemented, uncemented, hybrid and resurfacing groups from NJR (6th edition) data. Data validity was determined by interrogating for episodes of misclassification. We identified 6,034 (2.7%) misclassified episodes, containing 97(4.3%) revisions. Kaplan-Meier revision rates at 3 years were 0.9% cemented, 1.9% for uncemented,1.2% for hybrids and 3.0% for resurfacings (significant difference across all groups, p<0.001, with identical pattern in patients <55 years). Regression analysis indicated both prosthesis group and age significantly influenced failure (p<0.001). Revision for pain, aseptic loosening, and malalignment were highest in uncemented and resurfacing arthroplasty. Revision for dislocation was highest in uncemented hips (significant difference between groups, p<0.001). Feedback to the NJR on data misclassification has been made for future analysis.