The lateral collateral ligament is a circular cord about 5 cm long, located between the lateral epicondyle of the femur and the small head of the fibula, separated from the joint capsule by the N tendon and sparse tissue, and not connected to the meniscus. The external artery and nerve of the inferior knee cross its deep surface. During knee extension, this ligament is tense and, together with the iliotibial bundle, restricts knee inversion and tibial rotation. It relaxes during knee flexion, allowing a small amount of internal and external rotation of the lower leg. If the knee joint is overly pronated, it can cause an avulsion or tear of the lateral collateral ligament. The lateral collateral ligament is the primary stabilizing structure against inversion stress during knee extension, and a complete rupture of this collateral ligament ligament will cause lateral instability of the knee. Therefore, a complete rupture of the lateral collateral ligament should be treated surgically. (1) The middle part of the ligament can be sutured with Bunnell’s method, and a tendon strip, 6-8 cm long, can be cut from the anterior edge of the end of the biceps femoris tendon and sutured at the proximal end. (2) The laceration of the fibula can be attached to the bone with a thick silk thread fixed according to the Bunnell method; (3) The rupture at the upper stop should be repaired and reconstructed in situ by using the bone drilling method for the severed end. (2) repair of compound ligament injury (1) tear of the lateral collateral ligament and the attachment of the femoral epicondyle of the N muscle, the proximal end of the lateral collateral ligament can be fixed to the original attachment with screws with tooth washers, while the N muscle is fixed there with silk sutures; (2) the posterior lateral arch ligament and the bean-fibular ligament complex is torn from the small head of the fibula and is sutured with silk sutures; the upper end of the tear is sutured to the periosteum on the deep side of the lateral head of the gastrocnemius; if the tear If the tear is in the middle, interrupted sutures are made and the lateral edge is advanced and sutured to the posterior edge of the lateral median joint capsule and the posterior edge of the lateral collateral ligament. The biceps femoris tendon, gastrocnemius tendon and iliotibial bundle can also be used to strengthen the repair.