Recovery in horizontal gait after hip resurfacing vs. total hip arthroplasty at 6-month follow-up - a randomized clinical trial

Abstract

Standard total hip arthroplasty (THA) is the established surgical treatment for patients older than 65 years with progressive osteoarthritis. However, implant survivorship curves decline more rapidly in patients younger than 50 years. Resurfacing hip arthroplasty has therefore been suggested as an alternative for younger more active patients. Walking ability is one of the most common and useful outcome measures used in hip replacement patients, and the ability to safely ambulate is considered a pre-requisite for discharge from most orthopedic facilities. Improvements in walking ability and kinematics have been suggested after hip resurfacing, but no study sofar has objectively assessed this aspect in a randomized trial including standard THA. Purpose: To test the hypothesis that (i) a superior recovery in gait would be observed following resurfacing total hip arthroplasty compared to standard total hip arthroplasty and (ii) to investigate the hypothesized relationship between mechanical hip and knee muscle performance and horizontal gait function in patients with total hip replacement. Methods: Forty-three patients were randomized into either standard or resurfacing THA. Three-dimensional gait data were collected at self-selected normal and maximal walking speed. Primary outcome was gait speed while secondary outcomes comprised selected temporospatial and kinematic parameters obtained during horizontal walking. Explorative outcome was the relationship between isolated mechanical hip and knee muscle performance and horizontal gait function in younger THA patients 56 ± 6 years (range 44-64). Data was collected pre-operatively, 2 and 6 months post-operatively Results: There was no effect of treatment on horizontal self-selected normal speed, however an effect of treatment was observed on maximal walking speed where standard THA subjects walked faster than the hip resurfacing subjects (P = 0.03). No differences in the recovery of spatiotemporal parameters were observed. Also, peak hip flexion and peak hip adduction angles recorded during the stance phase were similar in both groups. Maximal isometric knee and hip muscle strength were positively associated with gait speed, step length and cadence during maximal walking (R2= 0.13-0.37, P < .05). Conclusions: The present data could not provide evidence to support the hypothesis that resurfacing total hip arthroplasty should lead to a superior recovery in gait and hip kinematics compared to standard 28-mm hip arthroplasty in younger hip arthritis patients. Maximal isolated leg muscle strength was a predictor of horizontal gait performance, and thus provides an important and valid functional outcome measure for individuals undergoing total hip arthroplasty.