Changes of and interrelationships between performance-based function and gait and patient-reported function 1 year after total hip arthroplasty

BACKGROUND: The aim of this prospective study is to evaluate the degree of improvement in, and interrelationships between, performance-based function, gait, and patient-reported function 1 year after total hip arthroplasty (THA) in patients with primary hip osteoarthritis (OA). MATERIALS AND METHODS: Thirty-four patients with hip OA, with a mean age of 67 years (standard deviation, SD 9 years), and 25 age- and gender-matched healthy controls performed three performance-based functional tests, instrumented three-dimensional gait analysis, and completed the Hip disability and Osteoarthritis Outcome Score prior to and 1 year after THA. Effect sizes with 95 % confidence intervals were calculated as measures of the magnitude of improvement in performance after surgery. RESULTS: Performance-based function displayed large improvements 1 year after THA. Overall gait patterns, quantified using a kinematic and a kinetic gait index, respectively, revealed moderate improvements in kinematics of the operated limb and kinetics of the contralateral limb. Patient-reported function displayed the largest improvement after surgery. CONCLUSIONS: The findings of this study suggest that objectively measured improvements in performance-based function and gait are not in line with patient-reported functional improvements, highlighting the importance of using both subjective and objective methods for evaluating function following THA. LEVEL OF EVIDENCE: III.