The purpose of this study was to explore the relationship between patients' self-reported and performance-based function after total hip arthroplasty (THA).
Twenty-three patients (age, 61.4 ± 8.3 yrs) undergoing primary THA for hip osteoarthritis participated. Self-reported function and recovery was measured using the Hip Disability and Osteoarthritis Outcome Score activities of daily living and pain subscales. Performance-based functional measures included the timed up and go test, the stair climbing test, and the 6-minute walk test. Outcome measures were assessed preoperatively and postoperatively at 1 and 6 mos.
One month after THA, performance-based function declined compared with baseline as follows: timed up and go test, -22.1% ± 25.4%; stair climbing test, -58.5% ± 63.6%; and 6-minute walk test, -22.6% ± 31.7%. In contrast, self-reported function on the Hip Disability and Osteoarthritis Outcome Score Activities of Daily Living significantly improved 1 mo after THA compared with baseline: 40.8% ± 33.3%. One to 6 mos after THA, there were significant improvements in timed up and go test, stair climbing test, and 6-minute walk test, which paralleled improvements on the Hip Disability and Osteoarthritis Outcome Score subscales, although changes were not significantly correlated.
The disparity between changes in Hip Disability and Osteoarthritis Outcome Scores and functional performance postoperatively suggests that patients may overestimate their functional capacity early after THA, likely in response to pain improvements over the same time period. Therefore, outcomes assessment after THA should include both self-report and performance-based functional measures.