Biomechanical mechanisms of toe-out gait performance in people with and without knee osteoarthritis

BackgroundToe-out gait modification (increased toe-out angle) has been proposed to decrease medial knee joint loading and slow disease progression in patients with knee osteoarthritis. However, the manner in which toe-out gait modification is performed is unknown. The purposes of this study were to assess the biomechanical strategies of achieving a toe-out gait, and to compare these strategies between older individuals with knee osteoarthritis and young, healthy individuals.MethodsLower limb biomechanics were evaluated for ten patients with knee osteoarthritis and for ten young, healthy individuals during treadmill walking. Two trials, consisting of natural gait followed by a ten degree increase in toe-out angle were performed. Transverse plane rotations of the thigh, shank and foot segments were calculated and compared between walking conditions and groups.FindingsExternal rotation changes with toe-out were significantly different between the thigh and shank, and thigh and foot (P < 0.001), but not between the shank and foot (P = 0.48). External rotation at each segment was not significantly different (P > 0.05) between groups, with the exception of thigh rotation during natural gait (P = 0.04).InterpretationCurrent findings suggest that increased toe-out gait is primarily achieved through rotation of the shank and foot, with less contribution from the thigh, and those individuals with knee osteoarthritis perform a toe-out gait biomechanically similar to young, healthy individuals. Gait modification programs should address individuals' limitations, such as joint stiffness, to ensure functional performance of toe-out gait modification.