Lateral wedges decrease biomechanical risk factors for knee osteoarthritis in obese women

Obesity is the primary risk factor for the development and progression of medial compartment knee osteoarthritis. Laterally wedged insoles can reduce many of the biomechanical risk factors for disease development in osteoarthritis patients and lean individuals but their efficacy is unknown for at-risk, obese women. The purpose was to determine how an 8° laterally wedged insole influenced kinetic and kinematic gait parameters in obese women. Gait analysis was performed on fourteen obese (average 29.3 years; BMI 37.2kg/m(2)) and 14 lean control women (average 26.1 years; BMI 22.4kg/m(2)) with and without a full-length, wedged insole. Peak joint angles, the external knee adduction moment and its angular impulse were calculated during preferred and standard 1.24m/s walking speeds. Statistical significance was assessed using a 2-way ANOVA (α=0.05). The insole significantly reduced the peak external knee adduction moment (mean decrease of 3.6±3.9Nm for obese and 1.9±1.8Nm for controls) and its angular impulse in both groups. The wedged insoles also produced small changes in ankle dorsiflexion (obese: 1.2±1.4° increase; control: 1.5±1.4° increase) and eversion range of motion (obese: 1.3±1.9° decrease; control: 1.5±1.2° decrease) but did not alter peak angles of superior joints. Although the majority of obese women may develop knee osteoarthritis during their lifetime, a prophylactic insole intervention could allow obese women with no severe knee malalignments to be active while preventing or delaying disease onset. However, the long-term effects of the insole have not yet been examined.