THE EFFECT OF HIP ABDUCTOR STRENGTHENING EXERCISES ON POSTURAL CONTROL AND GAIT FOLLOWING TOTAL KNEE ARTHROPLASTY

Abstract

Postoperative rehabilitation protocols for total knee arthroplasty (TKA) patients mainly focus on quadriceps strengthening exercises; as these exercises have been identified as a primary predictor of physical function following TKA.[1–5] Some studies have demonstrated that hip abductor muscles play an important role in stabilizing the trunk and controlling the lower limb during gait and physical function activities.[6,7] Activities that are common in daily life include ambulation, postural balance, moving quickly from a chair and moving in a figure 8 pattern to navigate obstacles. However, standard postoperative rehabilitation protocols do not typically target hip abductor strength.[8,9] The goal of this dissertation was to determine the effect of additional home strengthening intervention targeting hip abductor muscles to the standard of care on various aspects of functional performance following TKA. It was hypothesized that the additional home strengthening plus standard of care would produce greater improvements in postural balance, gait, functional performance, and self-reported measures compared to standard care alone. Main outcomes included postural control metrics during single leg stance (center of pressure displacement variability, amplitude and velocity of sway), gait parameters (spatiotemporal, kinematic and kinetic variables),functional performance (timed up and go [TUG], figure-8 walk [F8W], five times sit to stand [5-STS]), and self-reported measures (Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), Activities-specific Balance Confidence (ABC) Scale). Outcomes were assessed preoperatively and at three months following TKA. The results of this study indicated that eight-week of additional home strengthening intervention targeting hip abductor had no effect on postural control, gait biomechanics, and self-reported measures following TKA. However, significant improvements were found in isometric hip abductor strength of the non-surgical limb and in functional performance measures including TUG and F8W tests in the intervention group compared to the standard care group at month three. The demonstrated effect of targeting hip abductor strength on functional measures requiring more complex neuromotor control indicate the importance of abductor strengthening after TKA. Moreover, these findings demonstrate the value of these functional performance measures to document physical function progress after TKA.