Thigh suddenly too painful to bear may be trauma, muscle spasm, and lumbar disc herniation acute stage and other causes. 1. Trauma: due to trauma and other violent factors acting on the thigh, local bone, muscle, nerve and other tissue damage, may appear thigh suddenly too painful to bear the symptoms. 2. Muscle spasm: mostly occurring in the usual lack of exercise in the crowd, in the sudden movement, or hypocalcemia and other conditions, thigh muscle spasm, local ischemia, can appear leg suddenly too painful to bear. 3. Lumbar intervertebral disc herniation in the acute stage: generally due to lumbar intervertebral disc herniation compression of the nerve roots of the lower limbs, in the acute onset, the patient may appear leg suddenly severe pain. Thigh suddenly too much pain can not stand may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.