Fig. 6

A Dynamic change process of the maximum principal stress area during flexion; B Dynamic change process of the maximum principal stress area during extension; C Dynamic change pattern of the maximum principal stress area during elbow flexion and extension. In flexion from 0°-130°, the maximum principal stress decreases with the increase of the angle, and in extension, the maximum principal stress increases and then decreases with the increase of the angle, and reaches the peak at about 80°; D-F the relative displacement rule of the humerus in different flexion and extension angles. In flexion from 0°-130°, the relative displacement decreases and then increases with the angle and reaches the peak at about 40°. In extension, the relative displacement increases and then decreases with increasing angle, reaching a peak at about 80°