The tendon pain behind the foot and knee may be caused by physiological reasons such as overwork, or it may be caused by trauma, popliteal disease, arthritis, lumbar spine disease and other diseases. 1. Overexertion: It is common for patients to suffer from muscle and ligament spasms or metabolic disorders in the knees and ankles due to over-exercise or work, which may cause tendon pain behind the knees. 2. Trauma: When the posterior horn of the meniscus at the knee and the ligaments and other tissues at the ankle are torn due to trauma, the patient may have tendon pain behind the foot and knee. 3. Popliteal fossa disease: commonly seen in synovial cysts, tendon sheath cysts and other diseases, patients in the activities of extrusion or pulling the corresponding tissues, patients may appear behind the foot and knee tendon pain. 4. Arthritis: osteoarthritis, rheumatoid arthritis, rheumatoid arthritis and rheumatoid arthritis, in the longer course of the disease can be caused by meniscus, as well as articular cartilage and synovial lesions, the patient may appear behind the foot and knee tendon pain. 5. Lumbar spine disease: commonly seen in lumbar disc herniation, lumbar spine slipped and other degenerative diseases, compression of the nerve roots innervating the lower limbs, the patient may appear behind the knee tendon pain. The tendon pain behind the foot and knee may also have other reasons, it is recommended to consult a doctor in time, with the help of the doctor to clarify the cause of the disease, and targeted treatment or therapy.