Conclusions Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing , except when discontinued devices are removed from the analyses .
Background Metal-on-metal hip resurfacing was developed for younger , active patients as an alternative to THA , but it remains controversial .
Study heterogeneity , inconsistent outcome definitions , and unst and ardized outcome measures challenge our ability to compare arthroplasty outcomes studies .
Questions / purpose sWe asked how early revisions or reoperations ( within 5 years of surgery ) and overall revisions , adverse events , and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA  among patients with hip osteoarthritis .
Secondarily , we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries .
The Birmingham Hip Resurfacing: 5-year clinical and radiographic results from a District General Hospital
We prospect ively examined the functional and radiographic outcomes of a serial cohort of 104 Birmingham Hip Resurfacings in an independent centre . Final follow-up was to a mean of 61 months , and six cases were lost to follow-up . Excellent results were obtained in 91 % , but obese patients had significantly ( p < 0.03 ) poorer post-operative outcomes . Whilst there were no cases of neck fracture neck narrowing of up to 20 mm was noted . Radiolucent lines were present in a single zone in 9.4 % ( 9/96 ) acetabular and 3.1 % ( 3/96 ) femoral components . However , no components were definitely loose and there were no revisions for any reason during the period of the study . This independent series confirms that the Birmingham Hip Resurfacing gives excellent early clinical results and little early evidence of radiographic failure . The high rate of neck narrowing gives us cause for concern and we would recommend regular radiographic follow-up
Conclusions Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing , except when discontinued devices are removed from the analyses .
Background Metal-on-metal hip resurfacing was developed for younger , active patients as an alternative to THA , but it remains controversial .
Study heterogeneity , inconsistent outcome definitions , and unst and ardized outcome measures challenge our ability to compare arthroplasty outcomes studies .
Questions / purpose sWe asked how early revisions or reoperations ( within 5 years of surgery ) and overall revisions , adverse events , and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA  among patients with hip osteoarthritis .
Secondarily , we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries .