Anterior separation of the inferior tibiofibular joint is caused by the force of external rotation injury. The anterior portion of the talar body pushes against the external ankle, causing it to twist outward and backward, and commonly the anterior tibiofibular tuberosity is avulsed. However, most cases are tears of the anterior tibiofibular ligament itself. Later on, the synovial blind canal behind the ligament is torn and some fibers of the interosseous ligament are ruptured. When the fibula is externally rotated, the posterior tibiofibular ligament is also stressed and an avulsion fracture of the posterior tibiofibular labrum can occur, which is considered by scholars to be characteristic of external rotation injuries and implies that the anterior tibiofibular union is also separated. The avulsed bone fragment is small and rarely exceeds 1/4 of the articular surface. The following methods are used to examine the depression of the external ankle: 1. Bone densitometry. 2.Bone imaging. 3.CT examination of bone joint and soft tissue. In case of simple tibiofibular joint ligament injury, only closed reduction and calf cast immobilization for 6 weeks is required. In posterior tibial labral avulsion fractures, the fracture fragment does not exceed 1/4 of the articular surface and does not affect the joint, it can also be fixed in plaster. In cases with fibula fracture, for example, if the fracture can be repositioned, plaster fixation is still available. If the fracture is not satisfactorily repositioned, the fibula should be repositioned by incision and internal fixation, and after the fibula is firmly fixed, the calf should be fixed in plaster for 6 weeks.