Numbness in the left thigh, to consider sciatica pain, nerve entrapment, pear-shaped muscle syndrome and other causes, as follows: First, sciatica: the patient may be sciatica, such as a herniated lumbar disc, when the herniated disc tissue compresses the left spinal nerve root, there will be radioactive pain and numbness in the thigh. Second, nerve compression: consider the anterior lateral femoral cutaneous nerve compression, the god is often in the iliac spine area by the compression, which will cause numbness in the anterior lateral thigh. Third, pear-shaped muscle syndrome: pear-shaped muscle syndrome can also lead to compression of the sciatic nerve, which can manifest as radioactive pain in the back of the thigh, accompanied by numbness.