Evaluation of Joint Contact Forces in Subjects with Knee Osteoarthritis.

Background. Abnormal joint loading is a contributor factor to develop and progress of osteoarthritic knee joint degeneration. Various approaches have been used to measure joint contact forces in the patients with knee osteoarthritis (OA). Evaluation of knee adduction moment based on inverse dynamic (ID) approach is a surrogate marker for medical compartment loading in people with knee OA. It is controversial whether joint loading increases in this group of subjects or not. Therefore, the aim of this study was to evaluate knee joint contact force in the subjects with OA based on OpenSIM modelling approach. Methods. 10 knee osteoarthritic patients and 10 normal subjects with comparable age, height an weight were recruited in this study. A motion analysis system with 7 highspeed camera and a Kistler force plate was used to record the motions of the subjects while walking and the force applied on the legs, respectively. OpenSim software was used to evaluate joint contact forces. Results. Although the mean value of the second peak of GRF in OA group decreased significantly compared to normal subjects (P-value = 0.0005), the mean value of the force applied on the leg in midstance phase increased significantly compared to normal subjects (P-value = 0.0005). The range of motion of ankle, hip and knee joints decreased in OA group compared to normal subjects (P-value < 0.05). The peaks of knee joint contact forces decreased significantly in OA subject (P-value > 0.001). Moreover, the peak of joint contact force of ankle in OA group was less than that of normal subjects. Conclusions. The results of this study showed that the loads on knee joint (both based on moments and knee joints contact force omponents) of the subjects participated in this study was significantly less than that of normal subjects. This may be due to use of compensatory mechanisms selected by the subjects. It is highly recommended to repeat the research on more number of the subjects with various severities of knee joint OA. [ABSTRACT FROM AUTHOR]