In clinical practice, the phenomenon of a concave knee can lead to a number of conditions, such as a patient with knee dystocia, which is prone to this clinical manifestation due to knee ligament laxity or injury and knee joint loosening, and a patellar fracture if the patient’s patella is subjected to direct external force. After the fracture occurs, the fracture end will be separated and displaced due to muscle pulling, and there will be pain and depression when touching the area. After a patellar fracture, the patient can be treated surgically with an incision and internal fixation with a tension band, and after surgery, the patient can be instructed to perform early functional exercises to prevent knee stiffness.