The tendon pain at the bend of the leg may be caused by trauma, fasciitis, osteoarthritis, meniscus injury, ligament injury and lumbar disc herniation. 1. Trauma: external trauma is a common cause of pain in the hamstring at the bend of the leg. When external trauma leads to injury of the hamstring at the bend of the leg and pulling of the soft tissues, edema will be caused, which will lead to pain in the hamstring at the bend of the leg. 2. Fasciitis: when the patient is involved in strenuous exercise or prolonged heavy physical labor, it may lead to localized fascial inflammation, posterior meniscus angle injury and lumbar intervertebral disc herniation. It is often manifested as localized soreness and swelling. Since the leg bends are located at the joints, they are more likely to cause inflammation. 3. Osteoarthritis: Osteoarthritis of the knee joint can stimulate the synovial membrane of the leg at the bend of the leg when it is active, which leads to pain in the hamstring at the bend of the leg. 4. Meniscus injury: meniscus injury, especially the posterior horn of the meniscus injury, will stimulate the synovial membrane at the bend of the leg, resulting in hamstring pain at the bend of the leg. 5. Ligament injury: ligaments include lateral collateral ligaments and cruciate ligaments, which can cause pain in the soft tissues and tendons of the knee and tendons due to instability of the knee joint. 6. Lumbar disc herniation: Lumbar disc herniation can compress the sciatic nerve and cause radiating pain in the lower limbs, which can be transmitted to the knee joint and cause pain in the tendons and tendons at the bend of the leg. Therefore, if the patient has symptoms of hamstring pain at the bend of the leg, it is recommended to go to the hospital in a timely manner to identify the cause of the disease and carry out targeted treatment.