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 .
Prevalence of heterotopic ossification in cemented versus noncemented total hip joint replacement in patients with osteoarthrosis: a randomized clinical trial.
OBJECTIVE To determine the prevalence of heterotopic bone formation in cemented versus noncemented total hip joint replacement . DESIGN A prospect i ve r and omized controlled trial . Follow-up ranged from 2 to 6 years ( mean 4 years ) . SETTING A university hospital . PATIENTS Two hundred and twenty-six patients who had primary or secondary osteoarthrosis of the hip were stratified according to type of fixation , surgeon and age . Patients were r and omized within strata : 112 received noncemented total hip prostheses and 114 received cemented prostheses . The 2 groups were similar with respect to age and sex . INTERVENTION Primary total hip arthroplasty . A cemented ( methylmethacrylate ) or noncemented prosthesis was inserted by a lateral surgical approach . MAIN OUTCOME MEASURE The Brooker classification was used to grade heterotopic bone formation from postoperative radiographs . RESULTS Overall , 148 ( 66 % ) hips had no heterotopic ossification , 56 ( 25 % ) were Brooker class I , 14 ( 6 % ) were class II , 8 ( 3 % ) were class III and none were class IV . In the noncemented group of patients , 76 ( 68 % ) hips had no heterotopic ossification , 25 ( 22 % ) were Brooker class I , 7 ( 6 % ) were class II , 4 ( 4 % ) were class III and none were class IV . In the cemented group of patients , 72 ( 63 % ) hips had no heterotopic ossification , 31 ( 27 % ) hips were Brooker class I , 7 ( 6 % ) were class II , 4 ( 4 % ) were class III and none were class IV . CONCLUSION There was no significant difference in the prevalence of heterotopic ossification between cemented and noncemented total hip replacements in patients with osteoarthrosis
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 .