Total hip arthroplasty versus resurfacing arthroplasty in the treatment of patients with arthritis of the hip joint: single centre, parallel group, assessor blinded, randomised controlled trial.

objectivesTo compare the clinical and cost effectiveness of total hip arthroplasty with resurfacing arthroplasty in patients with severe arthritis of the hip.

designSingle centre, two arm, parallel group, assessor blinded, randomised controlled trial with 1:1 treatment allocation.

settingOne large teaching hospital in the United Kingdom.

participants126 patients older than 18 years with severe arthritis of the hip joint, suitable for resurfacing arthroplasty of the hip. Patients were excluded if they were considered to be unable to adhere to trial procedures or complete questionnaires.

interventionsTotal hip arthroplasty (replacement of entire femoral head and neck); hip resurfacing arthroplasty (replacement of the articular surface of femoral head only, femoral neck remains intact). Both procedures replaced the articular surface of the acetabulum.

main outcome measuresHip function at 12 months after surgery, assessed using the Oxford hip score and Harris hip score. Secondary outcomes were quality of life, disability rating, physical activity level, complications, and cost effectiveness.

results60 patients were randomly assigned to hip resurfacing arthroplasty and 66 to total hip arthroplasty. Intention to treat analysis showed no evidence for a difference in hip function between treatment groups at 12 months (t test, P=0.242 and P=0.070 for Oxford hip score and Harris hip score, respectively); 95% of follow-up data was available for analysis. Mean Oxford hip score was 40.4 (95% confidence interval 37.9 to 42.9) in the resurfacing group and 38.2 (35.3 to 41.0) in the total arthroplasty group (estimated treatment effect size 2.23 (-1.52 to 5.98)). Mean Harris hip score was 88.4 (84.4 to 92.4) in the resurfacing group and 82.3 (77.2 to 87.5) in the total arthroplasty group (6.04 (-0.51 to 12.58)). Although we saw no evidence of a difference, we cannot definitively exclude clinically meaningful differences in hip function in the short term. Overall complication rates did not differ between treatment groups (P=0.291). However, we saw more wound complications in the total arthroplasty group (P=0.056) and more thromboembolic events in the resurfacing group (P=0.049).

conclusionsNo evidence of a difference in hip function was seen in patients with severe arthritis of the hip, one year after receiving a total hip arthroplasty versus resurfacing arthroplasty. The long term effects of these interventions remain uncertain.

trial registrationCurrent Controlled Trials ISRCTN33354155, UKCRN 4093.