The symptoms of tendon pain when the leg is straightened, the common causes are the following: 1, injury and strain to the muscles, tendons and ligaments of the lower limbs, when the leg is straightened, it is easy to cause local injury aggravation, resulting in increased symptoms and painful symptoms. 2, seen in lumbar diseases, such as lumbar disc herniation, when the leg is straightened, it will produce the lower limbs of the back of the thigh, calf lateral appear radioactive The pain, the walk is also a linear walk, patients often mistakenly think it is tendon pain, but in fact it is a kind of nerve radiating pain. This test is mainly performed in the clinic for lumbar disc herniation, called the straight leg raise test, and also includes the straight leg raise test enhancement test, etc. It is recommended that patients with this symptom go to the hospital for a detailed examination to make a definite diagnosis.