Foot Pressure Pattern and its Correlation With Knee Range of Motion Limitations for Individuals With Medial Knee Osteoarthritis

Objective: To determine the foot pressure pattern of individuals with medial knee osteoarthritis (OA) and to analyze its relation with knee flexion/extension range of motion. Design: Descriptive. Setting: Rehabilitation center. Participants: Individuals with unilateral, painful medial knee OA (n=50; mean age, 75y; OA group) were enrolled as subjects, and young, healthy persons (n=50; mean age, 28y; young group) and elderly persons (n=44; mean age, 74y; elderly group) without any pain, deformity, or apparent OA changes in either knee were enrolled as controls. Intervention: Walking 10m at a comfortable speed. Main Outcome Measures: Partial foot pressures as percentages of body weight (%PFP), anteroposterior length of the center of pressure (COP) path as a percentage of foot length (%Long), transverse width of the COP path as a percentage of foot width (%Trans), knee flexion/extension range of motion (in the OA group). Results: The %PFP values for the heel and hallux, %Long, and %Trans were all significantly lower in the OA group than in controls (P<.001, all). Within the OA group, a limited range of knee extension was significantly associated with a short %Long (P<.001) but not with %Trans. Conclusions: Individuals with medial knee OA exhibited low pressure on the heel and hallux and short %Long of the COP path, and limitation of knee extension was associated with shortness of %Long. The shortness of %Long in the OA group likely resulted from insufficient knee extension during the heel-contact phase associated with low pressure on the heel. %Long is a useful parameter in gait analysis by using a foot pressure measurement system. Archives of Physical Medicine and Rehabilitation 2013;94:2502-8 (C) 2013 by the American Congress of Rehabilitation Medicine