Analysis of Contact Pressure at Knee Cartilage during Gait with Respect to Foot Progression Angle

One of the main causes that make knee osteoarthritis (OA) worse is load concentration at the medial compartment of knee cartilage. It is alternatively measured by employing knee adduction moment (KAM). Since toe-in gait decreases the 1st peak of KAM, it has been considered as a non-surgical prevention of OA progressing. However, direct measures such as contact pressure at knee cartilage in motion have not been available so far. Obtaining contact pressure at knee cartilage by FE analysis is difficult because exact muscle forces are not available and because FE model should be reconstructed at every stance phase. To obtain contact pressure at knee cartilage during gait, a method employing FE analysis based on motion analysis has been used in this study. Reference FE model of lower extremities was constructed and transformed to specific stance phases of gait. Ground reaction forces and muscle forces from motion analysis were employed as loading conditions. Finally, contact pressure distributions on knee cartilage at 1st peak, mid stance, 2nd peak could be obtained with respect to foot progression angle. The result shows that toe-in gait could be effective for knee OA patients by dispersing contact pressure concentrated in medial knee compartment to lateral part.