Pain when walking four months after lumbar spine surgery may be caused by infection, nerve compression still exists, nerve injury is still in the recovery period, nerve necrosis and other reasons. 1. Infection: due to bacteria and other pathogens infecting the incision, causing infection of the lumbar spine, muscles and other tissues, patients may experience pain when walking four months after lumbar spine surgery. 2. Nerve compression still exists: due to the surgery to completely lift the nerve compression or the reappearance of compression after surgery, patients may have pain when walking four months after lumbar spine surgery. 3. Nerve damage is still in the recovery period: Due to heavy nerve damage before surgery, the nerve has not fully recovered four months after lumbar spine surgery, and the patient may have pain when walking four months after lumbar spine surgery. 4. Nerve necrosis: If the postoperative nerve damage is heavy, and the nerve has been degenerated and necrotic, the patient may have pain when walking four months after lumbar spine surgery. There may be other reasons for walking pain four months after lumbar spine surgery. It is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.