Habitual patellar dislocation is a condition in which the patella leaves the center of the intercondylar fossa and slides to the front of the femoral epicondyle when the knee is bent, causing the knee joint to lose strength and affecting its normal function, which can lead to osteoarthritis of the knee joint in the long run. Arthroscopy and X-ray examination can show patellar dislocation. Most of them are due to abnormal development of the local structure of the knee joint, caused by minor trauma. Treatment The cause of habitual patellar dislocation should first be diagnosed, and then its treatment countermeasures should be determined. 1. Patients with insufficient muscle strength of the medial femoral oblique muscle can undergo strength training: while training, attention should be paid to the systematic nature of strength training and the overall improvement of muscle strength of both lower limbs to ensure the stability of the patellofemoral joint. Also pay attention to the relaxation of the lateral muscles of the knee joint. 2.Surgical treatment: Surgical treatment can achieve significant results for traumatic factors causing MPFL loss and congenital patellar dislocation. (1) Proximal patellar reconstruction: refers to the balance adjustment of soft tissues including the lateral support band, medial support band or distal medial femoral muscle. (2) Distal patellar reconstruction: refers to the internal, anterior, anteromedial or distal displacement of the tibial tuberosity after cutting it. Release of the lateral support band is usually performed in conjunction with proximal reconstruction or distal reconstruction. Postoperative rehabilitation After proximal/distal reconstruction, active rehabilitation should be performed to prevent and treat various postoperative complications, such as joint effusion, active inflammation and pain. 1. Postoperative rehabilitation after proximal reconstruction: Postoperative stage 1: healing period (week 0-6) Weight-bearing exercises, ROM (joint range of motion) exercises and muscle strength exercises, etc. Weight bearing follows the principle of progressive weight bearing within the tolerable range; ROM exercises include passive knee extension and active knee flexion in sitting position, with the goal of moving from 0 degrees of knee extension to 60 degrees of knee flexion 4 weeks after surgery; plyometric exercises include exercises for quadriceps, gluteus, external hip rotators, hamstrings, and calf muscles. Patellar release exercises should also be started during this period and must be performed medially, using their normal range of motion as a limit. The amount of weight bearing and ROM allowed must be determined by paying attention to the healing of the relevant tissues and the method of fixation used during the exercises. Postoperative phase II: functional recovery – gait, movement and muscle strength exercises (weeks 7-12) Criteria for entering phase II: good contraction of the quadriceps, ability to maintain knee extension when lifting the leg in extension The knee can be flexed to 90 degrees, and intra-articular bleeding and pain are controlled. The focus of rehabilitation is on gait training. At this stage, the knee should be flexed more than 90 degrees and 110 degrees at 8 weeks postoperatively; power bicycle exercises should be started when ROM exercises are allowed; systematic muscle strength training should be performed; balance training should transition from stable plane single-leg support to unstable plane single-leg support. Postoperative Phase III: Intensive plyometric and endurance training (weeks 13-17) Criteria for entering Phase III: regained functional ROM, normal gait, single-leg standing phase pelvis and knee stability. ROM exercises are still performed in this phase: active assistance techniques, supine sliding wall, bicycle exercises. Hip mobility exercises. Strength exercises: centrifugal pedaling, step-down exercises, tolerable range static squat exercises. Gait exercises remain the focus. Backward walking helps to enhance quadriceps control and dynamic balance. A subset of patients can perform hip flexibility exercises: supine 4-way stretch, hip adductor stretch, bilateral hip flexor stretch, etc. Postoperative phase 4: strengthening function and return to sports (week 18-25) This phase should be decided by the patient’s request. If the return to high level activities such as running, jumping and shear stepping are required, this phase must be performed to prepare accordingly. Prior to reciprocal exercise training, ensure that the patient has solid strength, adequate ROM, good centrifugal control of the quadriceps and pelvic control. The training starts with box jumping exercises and transitions to positioning jumps and standing jumps. Then to compound jumps in the tolerable range of both legs and later to single-leg jumps and long jumps. The patient is evaluated before returning to sports and whether he/she is ready to return to sports. 2. Post-operative rehabilitation after distal reconstruction Due to the slow progress of weight-bearing training and the risk of fracture caused by the surgery, the rehabilitation time after distal reconstruction is long. Phase I: (Weeks 0-6): This phase should be performed with a straight leg brace to immobilize the affected limb. ROM exercises: passive knee extension exercises with a towel roll under the heel; active ROM exercises in the sitting position; ROM goals of 0 degrees to 60 degrees at two weeks and 0 degrees to 90 degrees at six weeks postoperatively. Patellar release; muscle strength and flexibility exercises. Phase 2: (Weeks 7 to 14): ROM for knee flexion should be 120 degrees at 8 weeks postoperatively and normal range at 14 weeks. Quadriceps muscle strength exercises; ROM exercises; patellar release; gait exercises; power cycling; balance and proprioceptive training. Phase 3: (Week 15~22): Continue to intensify the exercises in Phase 2 and cross-train (stepper, bicycle, step machine), you should be able to step down 20 cm steps in this phase. Phase 4: (Week 36~44): Continue functional exercises and perform functional reciprocal movement training and start running exercises. A standard of achievement assessment is performed before returning to exercise.