In clinical practice, all joints in the human body have a certain range of motion, and the range of motion varies from one part of the joint to another. For example, if the knee is in extension, it is in a neutral position. The normal range of motion of the knee is 135 degrees of flexion and 0 degrees of extension, and up to 10 degrees of hyperextension, and if the patient has significant hyperextension, knee valgus can occur. The patient’s knee can be actively flexed up to 135 degrees and passively flexed up to 160 degrees. The human knee joint also undergoes axial rotation, with inward rotation of the toe, which can range from 0-30 degrees, and outward rotation of the toe, which can range from 0-40 degrees. The thumb and metacarpophalangeal joints of the human body can also have a certain degree of mobility. Flexion can reach 45-90 degrees, extension can reach 0-45 degrees, active flexion can reach 100 degrees, and hyperextension can reach 90 degrees.