The lateral collateral ligament is located in the posterior 1/3 of the lateral knee joint. The lateral collateral ligament of the knee begins at the lateral epicondyle of the femur and ends at the fibular tuberosity. The lateral collateral ligament is tense during knee extension and relaxed during flexion. During knee extension and flexion activities, the relaxation of the lateral collateral ligament caused by tibial rotation is mainly maintained by the tendon fibers surrounding the biceps femoris to maintain continuous tension and thus the stability of the joint. Closed simple rupture of the lateral collateral ligament of the knee is rare and can only occur when violence is applied to the medial knee or lateral calf, causing sudden inversion of the knee. Clinically, rupture of the lateral collateral ligament of the knee is often combined with injury to the lateral joint capsule, as well as injury to the N tendon, posterior cruciate ligament, meniscus, lateral head of the gastrocnemius, common peroneal nerve, iliotibial bundle, or biceps femoris tendon. Diagnosis: A strong inversion stress acting on the lateral aspect of the calf or, in the extended position, an external force acting on the medial aspect of the knee, causing an inversion injury, resulting in a limited and severe pain on the lateral aspect of the knee. Physical examination may reveal swelling near the fibular tuberosity, subcutaneous ecchymosis, and significant local pressure pain. The degree of swelling is often related to the extent of the combined injury, and those with significant swelling may have posterior joint capsule and intra-articular injuries associated with them. Knee joint dysfunction is limited in addition to movement due to pain. The degree of impairment also depends on the presence or absence of other combined injuries. When combined with common peroneal nerve injury, foot drop, loss of dorsal foot and lateral calf skin sensation or hypoesthesia may occur. A positive knee inversion stress test in extension and a negative knee in 30 degrees of flexion indicates a simple rupture or laxity of the lateral collateral ligament of the knee. X-rays, which show an avulsion fracture of the fibular tuberosity, and double knee radiographs in the inversion stress position of the lower leg, are of greater diagnostic value. MRI is of greater significance in confirming the diagnosis of this disease. Treatment: 1. Non-surgical treatment: for those with light injury and simple lateral collateral ligament injury of the knee. External plaster fixation, quadriceps training, symptomatic treatment. 2, surgical treatment: a, lateral collateral knee ligament repair method. b. Tightening of the lateral collateral ligament of the knee. c. Reconstruction of the lateral collateral ligament of the knee. d. Internal fixation of avulsion fracture by incision and exploration of the common peroneal nerve.