The posterior lateral horn or posterior lateral complex of the knee is an important structure in maintaining the posterior lateral stability of the knee, which is a complex composed of the lateral collateral ligament, N tendon complex, N fibular ligament, arch ligament and posterior lateral joint capsule. The first layer mainly contains the biceps femoris tendon and the iliotibial bundle. The second layer consists mainly of the lateral collateral ligament, N tendon and N peroneal ligament. The third layer is the joint capsule and the lateral head of the gastrocnemius muscle. The biceps femoris tendon, lateral collateral ligament, N tendon complex, and N peroneal ligament are usually considered as the main structures of the posterior lateral knee, which play a stabilizing and protective role for the posterior lateral knee, among which the lateral collateral ligament, N tendon complex, and N peroneal ligament are the most important structures, which form a solid triangle in the posterior lateral knee and have the effect of limiting the internal rotation of the knee and the posterior external rotation of the tibia relative to the femur . The lateral collateral ligament begins at the lateral ramus of the lateral femoral condyle and ends at the lateral aspect of the fibular head and the distal head of the anterior fibular process; it primarily limits internal rotation of the knee and also limits external rotation and posterior displacement of the tibia. The N muscle begins at the posterior medial end of the proximal tibia and gradually extends laterally to form a tendon that ends just below the attachment point of the lateral collateral ligament of the lateral femoral condyle, which is an important dynamic structure in the lateral knee structure; the N tendon primarily limits external rotation of the tibia and also has a secondary role in limiting tibial posterior translation and knee internal rotation. The N-fibular ligament starts near the N muscle-tendon junction, travels distally and laterally, and attaches to the medial aspect of the fibular styloid process; it plays an important role in preventing tibial retroversion and internal rotation of the knee, and also has a secondary role in limiting tibial external rotation. Knee PLC injuries account for 2% of all acute ligament injuries of the knee. Following a knee PLC injury, the knee exhibits significant instability of internal knee rotation and a significant increase in posterior lateral rotation displacement of the upper tibia, with the main symptoms being posterior lateral knee pain, hyperextension instability, and internal knee throw during walking. Neglecting the diagnosis and treatment of PLC injuries can lead to chronic postero-lateral instability of the knee and, in severe cases, to failure of cruciate ligament reconstruction and ultimately to the development of traumatic osteoarthritis. Therefore, it is very important to be familiar with the anatomical features of PLC to help make a correct diagnosis of PLC injuries and avoid missed diagnoses, so that knee injuries can be evaluated more comprehensively and accurately and a reasonable treatment plan can be formulated.