Article 22 (NIDRR) Effectiveness of Off-Axis Training on Improving Knee Function in Individuals with Patellofemoral Pain

Abstract

Patellofemoral pain (PFP) is thought to be associated with altered patellofemoral mechanics due to impaired neuromuscular control of the lower extremity, particularly on the frontal and transverse planes (i.e., off-axis motions). The purpose of this study was to examine the effectiveness of an off-axis training program on improving knee pain and function in individuals with PFP. Repeated measures design. Controlled, laboratory setting. Five subjects diagnosed with PFP participated in a six-week exercise program that consisted of a series of lower extremity off-axis neuromuscular training using a custom-made elliptical trainer that allows frontal-plane sliding and transverse-plane pivoting of the two footplates. Changes in knee pain and function post training were evaluated using Knee injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) scores. Subjects' lower extremity off-axis neuromuscular control was assessed by calculating the variability (i.e., standard deviation) of the foot rotation angle (FRA) and foot sliding distance (FSD) relative to the initial starting foot positions while performing a stepping task on the elliptical trainer. On average, subjects reported a higher KOOS and IKDC score following the 6-week off-axis training program. Decreased variability of the FRA and FSD were also observed post-training. An off-axis training program using a robotic elliptical trainer was effective in enhancing lower extremity neuromuscular control on the frontal and transverse planes. The enhanced off-axis neuromuscular control post-training was accompanied by a reduction in knee pain and improvement in knee function in persons with PFP.