No clear influence of preference bias on satisfaction and early functional outcome in resurfacing hip arthroplasty.

BACKGROUND AND PURPOSE: Hip resurfacing arthroplasty (RHA) is done in patients who often have a high preference for the method. This preference can influence the clinical outcome and satisfaction. We evaluated the potential influence of this preference bias. PATIENTS AND METHODS: From an ongoing randomized trial comparing RHA with total hip arthroplasty, 28 consecutive patients (28 hips) who had been allocated to an RHA were characterized as the "randomized" group. 22 other patients (24 hips) who had refused participation and had especially requested an RHA were characterized as the "preference" group. Harris hip score (HHS), Oxford hip score (OHS), University of California at Los Angeles activity scale (UCLA), Short Form 12 (SF-12), and visual analog scale satisfaction score (VAS) were assessed in both groups. RESULTS: Both groups had a high implant satisfaction score (97/100 for the "preference" group and 93/100 for the "randomized" group) at 12 months. The HHS, OHS, and UCLA were similar at baseline and also revealed a similar improvement up to 12 months (p < 0.001). Regarding the SF-12, the "preference" group scored lower on the mental subscale preoperatively (p = 0.03), and there was a greater increase after 12 months (p = 0.03). INTERPRETATION: We could not show that there was any influence of preference on satisfaction with the implant and early clinical outcome in patients who underwent RHA. The difference in mental subscale scores between groups may still indicate a difference in psychological profile.