Independent predictors of revision following metal-on-metal hip resurfacing: a retrospective cohort study using National Joint Registry data.
ABSTRACT Modern metal-on-metal hip resurfacing has been widely performed in the United Kingdom for over a decade. However, the literature reports conflicting views of the benefits: excellent medium- to long-term results with some brands in specific subgroups, but high failure rates and local soft-tissue reactions in others. The National Joint Registry for England and Wales (NJR) has collected data on all hip resurfacings performed since 2003. This retrospective cohort study recorded survival time to revision from a resurfacing procedure, exploring risk factors independently associated with failure. All patients with a primary diagnosis of osteoarthritis who underwent resurfacing between 2003 and 2010 were included in the analyses. Cox's proportional hazard models were used to analyse the extent to which the risk of revision was related to patient, surgeon and implant covariates. A total of 27 971 hip resurfacings were performed during the study period, of which 1003 (3.59%) underwent revision surgery. In the final adjusted model, we found that women were at greater risk of revision than men (hazard ratio (HR) = 1.30, p = 0.007), but the risk of revision was independent of age. Of the implant-specific predictors, five brands had a significantly greater risk of revision than the Birmingham Hip Resurfacing (BHR) (ASR: HR = 2.82, p < 0.001, Conserve: HR = 2.03, p < 0.001, Cormet: HR = 1.43, p = 0.001, Durom: HR = 1.67, p < 0.001, Recap: HR = 1.58, p = 0.007). Smaller femoral head components were also significantly more likely to require revision (≤ 44 mm: HR = 2.14, p < 0.001, 45 to 47 mm: HR = 1.48, p = 0.001) than medium or large heads, as were operations performed by low-volume surgeons (HR = 1.36, p < 0.001). Once these influences had been removed, in 4873 male patients < 60 years old undergoing resurfacing with a BHR, the five-year estimated risk of revision was 1.59%. In summary, after adjustment for a range of covariates we found that there were significant differences in the rate of failure between brands and component sizes. Younger male patients had good five-year implant survival when the BHR was used.
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ABSTRACT: A prospective, multi-center postmarket approval study has been ongoing since May 2006 to assess safety and efficacy of the first US FDA approved hip resurfacing implant. 265 patients have been enrolled at five study sites. The average age of the patients is 51.3years. There have been 7 revisions (2.4%) in the cohort to date. K-M survival curves for the cohort are 97.6% at 5years. There is a trend toward a gender difference in implant survivorship, with 98.6% of men and 94.7% of women free from revision. Metal ion analysis revealed median cobalt and chromium levels of 1.5ppb and 1.7ppb at 1year. In this prospective US study, the Birmingham Hip Resurfacing implant is demonstrating results comparable to those in the literature.The Journal of arthroplasty 03/2014; · 2.37 Impact Factor
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ABSTRACT: Total hip arthroplasty (THA) is the gold standard in the treatment of degenerative hip disease, especially in the older patient. Concerns regarding the higher levels of failure of traditional implants in younger, more active patients have led to a search for alternative arthroplasty techniques. Hip resurfacing (HR) is one of these alternatives. When compared with THA, HR has some theoretical advantages that stem from preservation of the patient’s normal proximal femoral anatomy and the use of a large diameter metal on metal bearing. This has the potential to more accurately replicate physiological hip function, reduce the risk of dislocation and allow higher levels of activity with minimal wear of the articulating surface. In addition, the preservation of proximal femoral bone stock offers the potential for easier revision options as would inevitably be required in younger patients. In order to be considered a suitable alternative, HR would need to demonstrate improvements or at least equivalence in functional outcomes and survivorship along with evidence of successful preservation of bone stock leading to good outcomes from future revision surgery. Whilst the recent expansion of data both in the orthopaedic literature and the mainstream media concerning the potentially devastating problems from large metal-on-metal (MoM) bearings in some settings carries some salient lessons for both the development, marketing and uptake of new orthopaedic implants, it should be put in the context of the resurfacing literature as a whole. In this review we aim to review the current evidence base for HR compared with THA and examine the current indications for the procedure.Orthopedic and Muscular System. 11/2014; 3(3):173.
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ABSTRACT: Against a backdrop of rising levels of obesity, we describe and estimate associations of body mass index (BMI), age and gender with time to revision for participants undergoing primary total hip (THR) or knee (TKR) replacement in the UK. Population-based cohort study. Routinely collected primary care data from a representative sample of general practices, including linked data on all secondary care events. Population-based cohort study of 63 162 patients with THR and 54 276 with TKR in the UK General Practice Research Database between 1988 and 2011. Risk of THR and TKR revision associated with BMI, age and gender, after adjusting for the competing risk of death. The 5-year cumulative incidence rate for THR was 2.2% for men and 1.8% for women (TKR 2.3% for men, 1.6% for women). The adjusted overall subhazard ratio (SHR) for patients with THR undergoing subsequent hip revision surgery, with a competing risk of death, were estimated at 1.020 (95% CI 1.009 to 1.032) per additional unit (kg/m(2)) of BMI, 1.23 (95% CI 1.10 to 1.38) for men compared with women and 0.970 (95% CI 0.967 to 0.973) per additional year of age. For patients with TKR, the equivalent estimates were 1.015 (95% CI 1.002 to 1.028) for BMI; 1.51 (95% CI 1.32 to 1.73) for gender and 0.957 (95% CI 0.951 to 0.962) for age. Morbidly obese patients with THR had a 65.5% increase (95% CI 15.4% to 137.3%, p=0.006) in the subhazard of revision versus the normal BMI group (18.5-25). The effect for TKR was smaller (a 43.9% increase) and weaker (95% CI 2.6% to 103.9%, p=0.040). BMI is estimated to have a small but statistically significant association with the risk of hip and knee revision, but absolute numbers are small. Further studies are needed in order to distinguish between effects for specific revision surgery indications.BMJ Open 01/2013; 3(11):e003614. · 2.06 Impact Factor