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 .
Dislocation of Primary Total Hip Arthroplasty with 36 and 40-mm Femoral Heads
Some authors suggest the use of larger ( 36 and 40 mm ) femoral heads against highly cross-linked polyethylene acetabular liners will reduce the prevalence of early dislocation after primary total hip arthroplasty ( THA ) . We prospect ively followed 61 consecutive patients at high risk for dislocation to determine the prevalence of early dislocation after primary THA with 36 and 40 mm femoral heads .  We established specific indications for the use of these larger heads in primary arthroplasty . There were 65 hips in 61 patients with a minimum followup of 1 year ( mean 2 years , range 1 - 4 years ) . There were 55 36 mm heads and 10 40 mm heads . All arthroplasties were performed by the posterior approach with capsular repair . The prevalence of early dislocation was 4.6 % ( 3 of 65 ) . There was one patient with an anterior dislocation and two with posterior dislocation . No patient underwent reoperation for dislocation . There was no dislocation in the 10 hips that had a 40 mm head . We identified no complications related to the larger femoral heads . The use of larger femoral heads did not notably reduce the prevalence of early dislocation after primary THA in high risk patients compared to historical controls . Therapeutic study : Level IV , case series . See Guidelines for Authors for a complete description of levels of evidence
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 .