Knee medial tendon sprain more than forty days still hurts because it may be muscle strain, ligament damage, meniscus injury and other reasons. 1. Muscle strain: strenuous exercise or activities too large, it is easy to lead to muscle strain, mild muscle strain general 1 ~ 2 weeks can be recovered, if the muscle strain is serious, or strain after insufficient rest, improper treatment, will lead to more than forty days of pain is not yet recovered phenomenon. 2. Ligament injury: acute sprain of the knee joint will cause ligament injury, mild injury can be gradually relieved through rest and braking, if more than forty days still hurts, should consider the ligament partially ruptured or completely ruptured, usually need a plaster or brace fixation, or even surgical suture. 3. Meniscus injury: knee sprain more than forty days still hurts, should also be considered may be accompanied by meniscus injury, meniscus injury can be conservative treatment, such as physical therapy or drug treatment, the serious need for surgical treatment. The medial knee tendon sprained more than forty days still hurt should be given enough attention, it is recommended that patients go to the hospital in time to identify the cause and targeted treatment.