Purpose: There is scant information at present on the effects of severe osteoarthritis (OA) of the knee joint on gait. In the present study the kinematic and kinetic parameters of gait and the pattern of activation of four lower limb muscles were examined during walking at a self-selected pace on level ground. The spatiotemporal parameters of gait were also computed.

Methods: Measurements were made using a three-dimensional optico-electronic motion analysis system integrated with a force plate and telemetered electromyography.

Results: Fifty-eight patients with severe OA of the knee and 25 age-matched healthy control subjects were examined. Patients demonstrated a significantly reduced walking speed, shorter stride length and a more prolonged stance phase of the gait cycle compared with the control subjects. They also had less range of motion at the hip, knee and ankle, joints and generated less moments and powers at the ankle and more moments at the knee than the control group. The differences were statistically significant for all parameters except the degree of ankle plantar flexion in stance. Activation of the rectus femoris muscle was prolonged in the patients group.

Conclusions: It is concluded that the observed gait abnormalities were due to instability of the knee joint in stance. This may have important clinical implications for the rehabilitation of patients with severe OA of the knee.