2. Methods

We modularized the post-cum alignment by three parameters in three levels respectively (Fig.1). The shape of the post's sagittal section and the total shape of cum were unchanged. The three parameters for modularization were the post location which was shifted anterior and posterior by 5 mm from the neutral position, the post inclination which was inclined forward and backward by 5° from the vertical, and the radius of curvature of the post's horizontal section which was increased and decreased by 2 mm from the original value. It is crucial to decrease contact stress between the post and cum during praying for the Muslim and during gardening or golfing for the Westerner, which would be realized by choosing the optimal location and inclination of post when kneeling for the Muslim and when squatting for the Westerner respectively (Fig.2). As for the Asian, it is desirable for them to perform various kinds of sedentary sittings on a floor without difficulties, which would be facilitated by choosing the optimal radius of curvature value to increase range of rotation when the knee is in high-flexion (Fig.2). First we performed a mathematical model analysis to introduce the kinetic data during sit-to-stand activities. Then by using the above kinetic data we performed the FEM analysis to determine the contact stress between the post and cum during praying, gardening or golfing. Finally we carried out the cadaveric study to determine the range of rotation at high flexion of the knee.