Hamstring pain in the hamstring behind the knee can be caused by trauma, knee osteoarthritis, lumbar disc herniation, popliteal cysts, etc. 1. Trauma: Running, jumping and other strenuous activities or external impact can lead to ligament damage inside the knee joint. Symptoms of hamstring pain behind the knee may occur. 2. Knee arthritis: it may be related to age, obesity, inflammation, trauma and genetic factors. There will be different degrees of knee pain, swelling, deformity, activity limitation and other clinical symptoms, advanced muscle atrophy and even ligament atrophy, joint extension will appear behind the knee hamstring pain. 3. Lumbar disc herniation: patients often have lumbar pain and sciatica, of which sciatica is often manifested as pain in the buttocks, posterior thigh and posterior lateral calf, mostly related to accumulation of injuries, pregnancy, genetic factors and congenital developmental abnormalities. 4. Popliteal cyst: patients often show symptoms of meniscus injury or cartilage injury, including pain in the posterior or posterior medial aspect of the knee joint, a feeling of suffocation and joint stiffness. It is mostly associated with increasing age and abnormally high pressure in the joint cavity. If you experience hamstring pain in the hamstring behind the knee, it is recommended that you visit a hospital promptly to clarify the cause.