Multi-axis joints mainly include shoulder and hip joints. Multi-axis joints are joints with more than two axes of motion and can do multi-directional movements, usually including ball and socket joints and planar joints, as follows: 1. Ball and socket joints: Ball and socket joints are joints with a relatively large, spherical head, while the joint socket is relatively shallow and small, with less than 1/3 of the contact area of the joint head, such as the shoulder joint, and ball and socket joints also have a relatively large part of the joint head wrapped around, such as the hip joint. 2. Planar joints: Planar joints mainly refer to two bones with a flat and smooth joint surface, but with a certain bend and curvature, and can do multi-axis sliding and rotation, such as intercarpal joints and attached metatarsal joints. The above joints can usually play the role of a larger range of motion, to assist patients to complete more complex movements, usually should pay attention to protection, otherwise easy to joint dislocation, joint injury.