Removal of acetabular bone in resurfacing arthroplasty of the hip

The clinical and radiological outcomes of hip resurfacing versus total hip arthroplasty: a meta-analysis and systematic review

BACKGROUND AND PURPOSE

Hip resurfacing (HRS) procedures have gained increasing popularity for younger, higher-demand patients with degenerative hip pathologies. However, with concerns regarding revision rates and possible adverse metal hypersensitivity reactions with metal-on-metal articulations, some authors have questioned the hypothesized superiority of hip resurfacing over total hip arthroplasty (THA). In this meta-analysis, we compared the clinical and radiological outcomes and complication rates of these 2 procedures.

METHODS

A systematic review was undertaken of all published (Medline, CINAHL, AMED, EMBASE) and unpublished or gray literature research databases up to January 2010. Clinical and radiological outcomes as well as complications of HRS were compared to those of THA using risk ratio, mean difference, and standardized mean difference statistics. Studies were critically appraised using the CASP appraisal tool.

RESULTS

46 studies were identified from 1,124 citations. These included 3,799 HRSs and 3,282 THAs. On meta-analysis, functional outcomes for subjects following HRS were better than or the same as for subjects with a THA, but there were statistically significantly greater incidences of heterotopic ossification, aseptic loosening, and revision surgery with HRS compared to THA. The evidence base showed a number of methodological inadequacies such as the limited use of power calculations and poor or absent blinding of both patients and assessors, possibly giving rise to assessor bias.

INTERPRETATION

On the basis of the current evidence base, HRS may have better functional outcomes than THA, but the increased risks of heterotopic ossification, aseptic loosening, and revision surgery following HRS indicate that THA is superior in terms of implant survival.

Metal-on-metal hip resurfacing: a skeptic's view

Contemporary metal-on-metal hip resurfacing is the third attempt by its proponents to eliminate a diaphyseal femoral component. I have multiple objections with the resurfacing concept and believe even the premises for the use of resurfacing invalid. There is a high rate of success with circumferential bead or mesh-coated uncemented stemmed femoral components at 10 to 20 years and there have been no long-term adverse consequences of femoral stress shielding with a diaphyseal component. More acetabular bone may be removed with resurfacing, negating its "conservative" premise. One computer simulation suggested the range of hip motion might be considerably less with resurfacing compared with conventional hip arthroplasty. There are a very limited number of patients for whom hip resurfacing is truly indicated, and the femoral head may be unsuitable for resurfacing in 40% of selected patients. Resurfacing is technically more difficult than conventional hip arthroplasty. Early complications and revision for femoral neck fractures are more likely with resurfacing. Blood and urine metal ion levels, capsular lymphocytic aggregation, and hypersensitivity are concerns with metal-on-metal articulation. Metal-on-metal hip resurfacing should only be used by a limited number of hip surgeons. The risks and complications of metal-on-metal hip resurfacing outweigh any possible advantages.