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 .
A comparison of total hip resurfacing and total hip arthroplasty - patients and outcomes.
A comparison of pertinent preoperative and postoperative data relative to total hip resurfacing versus total hip arthroplasty ( THA ) would assist in evaluating current perceptions in outcome . We compared 50 consecutive metal-metal resurfacing replacements in 50 patients with 44 consecutive conventional total hip arthroplasties in 35 patients , who were implanted during the same time period , by the same surgeon , and followed prospect ively for 2 to 4 years . The patients undergoing hip resurfacing were 62 % male , 9 years younger , and 3.2 inches taller , with a lower mean body mass index and American Society of Anesthesiologists ( ASA ) grade than patients undergoing total hip arthroplasty .  Preoperatively , patients undergoing resurfacing had a lower Harris hip score ( 46 vs 52 points ) , more pain , higher UCLA ( University of California at Los Angeles ) activity scores ( 4.2 vs 3.6 ) , and better range of motion . Surgical time for resurfacing was 18 % longer , but there was less total blood loss and fewer transfusions . Postoperatively , there was no difference in Harris hip score ( 97 vs 96 ) . Patients undergoing resurfacing had higher function , Short Form-12 physical activity scores , and UCLA activity scores , but also a higher incidence of slight or mild pain . There were no differences in postoperative range of motion or dislocation ( one each ) . The preoperative characteristics and general health status of the average patient undergoing resurfacing are more favorable than that of the average patient undergoing conventional total hip arthroplasty . Caution should be applied in attributing differences in outcomes directly to the arthroplasty technology
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 .