Three dimensional gait biomechanics following direct anterior total hip arthroplasty : a longitudinal study

Abstract

Background: The purpose of this study was twofold: 1) to prospectively investigate gait biomechanics following direct anterior (DA) total hip arthroplasty (THA) to identify the short term recovery and time sequence of return to normal gait; and 2) to investigate the force distribution across the surgical and nonsurgical legs and identify any possible asymmetries in dynamic load. Methods: Nine THA patients undergoing DA THA and nine control participants of similar mean age, underwent walking gait trials prior to and at three and six weeks after DA THA surgery. Walking biomechanics were collected via a three-dimensional motion capture system, and processed using Nexus software. Selected hip, knee, ankle, thorax, and pelvic kinetic and kinematic data were analyzed. Results: The two-way Repeated Measures Analyses of Variance revealed significant kinematic and kinetic differences in walking gait between the DA THA and the control groups at pre-surgery, and at three and six weeks following surgery. At the six week post-surgery data collection period, DA THA subjects reported decreased hip flexion/extension excursion (p=0.004), hip abduction/adduction excursion (p=0.01), and a decreased contralateral hip excursion (p=0.023) when compared to the control group. Force distribution comparisons between the surgical and non-surgical legs of the DA THA group indicated a significant main effect for hip extension moment, with the lower values across the surgical leg (p=0.023). No other kinetic variables were significantly different between legs. Conclusions: Short term analysis following DA THA revealed impairments in walking gait at six weeks post-surgery. Hip abduction moment however, was not significantly different from the control group during the pre-surgery or three and six week post-surgery. Also, force distribution comparisons between the surgical and nonsurgical legs revealed lower values in the surgical leg for hip extension moment only. No other joints of the lower extremity were significantly affected.