The posterior cruciate ligament is an important factor in stabilizing the knee joint and is the strongest ligament in the knee joint, guiding and limiting knee motion. PCL injuries are most often seen in traffic accidents, accounting for 33.16% of PCL injuries, and are mostly compound ligament injuries. Posterior cruciate ligament injuries can lead to further laxity of the secondary stabilizing factors of the knee, resulting in local pain, swelling, and instability. Based on the history of trauma, symptoms, signs, X-rays, and MRI, most patients with posterior cruciate ligament injuries can be definitively diagnosed. When the posterior drawer test is negative, additional examinations should be performed under anesthesia, and the aforementioned x-ray examinations, which often yield positive results. Non-operative treatment The common criteria for non-operative treatment are: posterior drawer sign <10 mm (grade II) in neutral tibial rotation and abnormal rotational laxity <5°; no significant abnormal laxity of internal or external rotation. For simple PCL fracture or incomplete fracture, the affected knee can be fixed in flexion at 30° with a long-leg cast first, and care should be taken to push the upper end of the affected tibia forward to match the normal knee pattern for 6 weeks before the cast is hardened. Exercise the quadriceps during immobilization to avoid muscle atrophy. Early surgical repair of ligaments Indications 1. Displaced tibial stop avulsion fracture; 2. Combined with meniscal injury with joint interlocking, which cannot be self-resolved, should be repaired by early surgery; 3. Severe knee dislocation, anterior and posterior cruciate ligament rupture, posterior external angle injury should be operated urgently, especially the posterior external angle injury should be repaired early. Late PCL injury Indications for surgery Patients are young, generally under 45 years of age, with recurrent knee pain, swelling, instability, posterior drawer sign grade III (posterior laxity >10mm), and are generally considered for surgical reconstruction, if accompanied by posterior external or posterior medial rotational instability, is an absolute indication for surgery. The indications for surgery can be slightly relaxed for athletes.