A randomized pilot study of a comprehensive postoperative exercise program compared with usual care following primary total hip arthroplasty in subjects less than 65 years of age: feasibility, selection of outcome measures and timing of assessment

Background: Total Hip Arthroplasty (THA) is being used more commonly in younger higher demand patients. The purpose of this randomized pilot study was to explore a) feasibility of comprehensive postoperative rehabilitation compared to usual care following primary THA in subjects <65 years, b) appropriate outcome measures including performance-based measures and c) timing of assessments. Methods: 21 subjects who underwent primary THA were randomized to receive a three-month out-patient rehabilitation program (Intervention) or usual postoperative care (Control). Subjects were assessed preoperatively, six-weeks postoperatively (Pre-intervention) and four and 12 months postoperatively (Post-intervention). Self-report measures were the Western Ontario McMaster Osteoarthritis Index (WOMAC) and Rand 36-Item Health Survey (RAND-36). Performance-based measures included lower extremity strength, walking speed and endurance, and gait laboratory assessment. Results: Ten Control and 11 Intervention subjects with an average age of 53.4 (SD9.3) years were randomized. All Intervention subjects completed the program without adverse effects. Although no statistically significantly results were reported, four months postoperatively, Intervention subjects had clinically important differences (CID) in strength compared with Control subjects. Walking endurance, WOMAC and RAND scores improved significantly with no CID noted between groups. Ten (48%) subjects reported a ceiling effect on the WOMAC (9 (43%) subjects on Pain; 1 (5%) subject on Function). No group CID were noted in gait measures. Conclusions: Our recommendations would be that performance-based strength measures should be considered for the primary outcome in this younger cohort. Because of the ceiling effects with WOMAC Pain, a different pain measure is indicated. Other more challenging functional performance-based tests should be considered such as a more prolonged endurance test. There is merit in one-year follow-up as strength improved after four months in both groups.