Possible causes of pain in the lower lumbar region and the upper hip include: ankylosing spondylitis, lumbar disc herniation, and femoral head necrosis. 1. Ankylosing spondylitis: Ankylosing spondylitis is a kind of inflammation of spinal ligaments and attachment points of intervertebral discs, which occurs in young and middle-aged men, and is mostly caused by the sacroiliac joints, and it can gradually affect the spine upward or cause arthritis of the hip and knee downward. Initially, lumbosacral discomfort or hidden pain may appear, and then the symptoms gradually worsen, and when hip arthritis is caused, pain in the buttocks, hips and other parts of the body may appear. 2. Lumbar disc herniation: the most common symptom of lumbar disc herniation is lumbar pain, and it can cause radiating neuralgia when it causes compression of the nerve root at the back, which is manifested as pain in the buttocks, the back and outer thighs, and the outer side of the calves. 3. Necrosis of femoral head: various reasons lead to the reduction or interruption of blood supply to the femoral head can cause ischemic necrosis of the femoral head, which at the initial stage is mainly manifested as vague pain and discomfort around the hip joints, buttocks, thighs, or inguinal area, and with the progress of the disease, the pain symptoms progressively aggravate, accompanied by difficulties in the hip joint activities. It is recommended to go to the hospital as soon as possible to find out the cause of pain in the lower back and upper hip and treat it accordingly.