Effect of Knee Osteoarthritis Progression on Knee-Joint Kinematics and Kinetics during Gait

Knee osteoarthritis (knee OA)is caused by abnormal knee joint mechanics.In order to prevent knee OA progression and achieve this recovery, the mechanical factors affected by knee OA during weight bearing activities, such as gait, need to be clarified.The purpose of this study was to analyze knee joint kinematics and kinetics during gait in patients with knee OA of various severities.A total of 69 knees (62 adults)were divided into three groups (26 normal knees, 16 mild OA knees and 27 severe OA knees) .Each subject's gait was measured by a motion capture system, and the relative femorotibial motion was estimated by a bi-planar roentgenography using the three-dimensional reconstruction technique.Knee kinetics was evaluated based on joint reaction force and joint moment.The point of intersection of the loading axis of the knee (LAK)on the tibial proximal surface was also calculated, and this point was defined as the 'LAK point'.During stance phase of gait, the knee flexion range, knee anteroposterior shift and anteroposterior range of LAK-point trajectory were significantly decreased in severe OA knees, whereas the medial-lateral direction range of the knee-joint reaction force was significantly increased.The anteroposterior range of LAK-point trajectory was also small in mild OA knees.Moreover, in severe OA knees, the LAK point tended to shift rapidly medially during the loading response.As knee OA progressed, the upper body weight was more locally loaded on the tibial surface, with an increased medial-lateral force in the knee joint.These findings suggest that mechanical transitions may be affected knee OA progression.