The common factors of stiffness of the knee joint and inability to bend the leg include long-term bed rest or postoperative joint adhesion, etc. Rehabilitation training can be carried out, such as joint training, muscle training, etc. It may also be caused by various types of joint inflammation, which may require surgical treatment, such as artificial knee replacement, arthroscopic minimally invasive surgery. 1.Rehabilitation training (1) Joint training: including seated leg raising training, seated kicking training, seated knee bending training and knee joint resistance training, etc., step by step, under the guidance of the doctor to exercise the knee joint, so as to increase the flexibility of the joint. (2) Muscle training: including quadriceps and gastrocnemius training. Patients because of long-term bedridden can lead to muscle atrophy, muscle strength is weak, can affect the joint extension and flexion, so the active contraction of muscle training should be carried out in order to enhance muscle strength, so as to get a better rehabilitation effect. 2.Surgical treatment (1) Artificial knee replacement: If the joint stiffness is accompanied by serious joint deformity and damage, artificial knee replacement can be chosen, and the joint function can be restored with rehabilitation training after the operation. (2) Arthroscopic minimally invasive surgery: such as arthroscopic joint release surgery, which can effectively restore the range of motion of the joints, and after the surgery, with timely muscle and joint rehabilitation training, joint function can be gradually restored. If the knee joint is stiff and the leg cannot bend, it is recommended that the patient go to the hospital in time to clarify the cause of the disease and give targeted rehabilitation training and treatment according to the condition.