Ipsilateral and contralateral foot pronation affect lower limb and trunk biomechanics of individuals with knee osteoarthritis during gait

•Lateral wedges increase shank rotation in knee osteoarthritis individuals.•Lateral wedges affect trunk kinematics in individuals with knee osteoarthritis.•Lateral wedges on the healthy side increase knee osteoarthritis adduction moments.•Increased foot pronation should not be overlooked in knee osteoarthritis individuals.•Knee osteoarthritis individuals report less comfort walking with lateral wedges.

BackgroundLateral wedges have been suggested for the treatment of individuals with knee osteoarthritis, but it may have undesirable effects on the biomechanics of gait through increased foot pronation. This study investigated the effects of increased unilateral foot pronation on the biomechanics of individuals with knee osteoarthritis during gait.MethodsBiomechanical data of twenty individuals with knee osteoarthritis were collected while they walked in three conditions: i) flat sandals; ii) wedged sandal on the knee osteoarthritis limb and flat sandal on the healthy limb; and iii) flat sandal on the osteoarthritis and wedged sandal on the healthy limb. Knee pain and comfort were evaluated. Principal Component Analysis followed by ANOVA was implemented to identify differences between conditions.FindingsThe wedged sandal on the osteoarthritis limb increased rearfoot eversion (P < 0.001; ES = 0.79); increased shank rotation range of motion (P < 0.001; ES = 0.70); reduced knee internal rotation moment (P < 0.001; ES = 0.83); reduced hip internal rotation moment (P = 0.001; ES = 0.66); increased ipsilateral trunk lean (P = 0.031; ES = 0.47); and increased trunk rotation range of motion (P = 0.001; ES = 0.69). Walking with the wedged sandal on the healthy limb increased hip (P = 0.003; ES = 0.61) and knee (P = 0.002; ES = 0.63) adduction moments. Individuals reported greater comfort walking with the flat sandals (P = 0.004; ES = 0.55).InterpretationIncreased unilateral foot pronation of the knee osteoarthritis and healthy limbs causes lower limb and trunk mechanical changes that may overload the knee and the lower back, such as increased knee adduction moment, shank rotation and trunk lateral lean. Foot motion of both lower limbs should be evaluated and care must be taken when suggesting lateral wedges for individuals with knee osteoarthritis.