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 results of primary Birmingham hip resurfacings at a mean of five years. An independent prospective review of the first 230 hips.
We report an independent prospect i ve review of the first 230 Birmingham hip resurfacings in 212 patients at a mean follow-up of five years ( 4 to 6 ) . Two patients , one with a loose acetabular component and the other with suspected avascular necrosis of the femoral head , underwent revision . There were two deaths from unrelated causes and one patient was lost to follow-up . The survivorship with the worst-case scenario was 97.8 % ( 95 % confidence interval 95.8 to 99.5 ) . The mean Harris hip score improved significantly ( paired t-test , p < 0.05 ) from 62.54 ( 8 to 92 ) pre-operatively to 97.7 ( 61 to 100 ) at a mean of three years ( 2.1 to 4.3 ) , then deteriorated slightly to a mean of 95.2 ( 47 to 100 ) at a mean of five years . The mean flexion improved from 91.5 degrees ( 25 degrees to 140 degrees ) to 110.4 degrees ( 80 degrees to 145 degrees ) at a mean of three years with no further improvement at five years ( 111.2 degrees ; 70 degrees to 160 degrees ) . On radiological review at five years , one patient had a progressive lucent line around the acetabular component and six had progressive lucent lines around the femoral component . A total of 18 femoral components ( 8 % ) had migrated into varus and those with lucent lines present migrated a mean of 3.8 degrees ( 1.02 degrees to 6.54 degrees ) more than the rest . Superolateral notching of the femoral neck and reactive sclerosis at the tip of the peg of the femoral component were associated with the presence of lucent lines ( chi-squared test , p < 0.05 ) , but not with migration of the femoral component , and are of unknown significance . Our results with the Birmingham hip resurfacing continue to be satisfactory at a mean follow-up of five years
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 .