Medial knee pain and not dare to bend is commonly seen in the following situations: First, the more common is osteoarthritis of the knee joint, especially when the medial osteoarthritis is more serious, it will lead to more serious lesions on the medial side of the knee joint, which will trigger the narrowing of the medial interstitial compartment, and ultimately lead to more serious osteoarthritis of the knee, which will trigger the medial pain and affect the flexion and extension. Secondly, it may be caused by the injury of medial meniscus of the knee joint, when the medial meniscus is injured, it will cause obvious pain in the medial side of the knee joint, and accompanied by functional limitation. Third, it may also be caused by the injury of the medial collateral ligament of the knee joint.