Determination of Leg Alignment in Hip Osteoarthritis Patients with the EOS® System and the Effect on External Joint Moments during Gait

The present study considered the entire leg alignment and links static parameters to the external joint moments during gait in patients with hip osteoarthritis. Eighteen patients with unilateral hip osteoarthritis were measured using the EOS® system. Clinical leg alignment and femoral parameters were extracted from the 3D reconstruction of the EOS images. A 3D gait analysis was performed and external knee and hip adduction moments were computed and compared to 18 healthy controls in the same age group. The knee adduction moments of the involved leg were strongly correlated to the femoral offset and the varus/valgus alignment. These parameters alone explained over 50% of the variance in the knee adduction moments. Adding the pelvic drop of the contralateral side increased the model of femoral offset and varus/valgus alignment and explained 78% of the knee adduction moment during the first half of the stance phase. The hip adduction moments were best associated with the hip kinematics and not the leg alignment.