Patellar ligament laxity will cause the patella to move upward, affecting the balance of forces in the knee joint, and the patient will have persistent and chronic pain in the knee joint, with mild localized swelling, positive tenderness, obvious looseness and instability of the knee joint, friction of the cartilage in the joint, and meniscus and synovial injuries. The patient may also have knee girdle insertion, with increased pain and popping when moving, and the patient’s knee range of motion is reduced, which can be clearly diagnosed by taking an MRI film. Treatment can be used to immobilize the knee joint with a brace, while applying topical plasters for bruises to promote the recovery of the damaged patellar ligament as soon as possible.