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.