After several lower spinal nerves join to form the sciatic nerve it runs behind the hip joint on the way down the back of the leg. A disc protrusion sometimes causes only hip pain, but most of the time hip pain is due to arthritis or other abnormalities in the hip joint itself.
The FABER test (stands for Flexion, Abduction and External Rotation) of the hip joint, as illustrated in the app, will cause increased hip pain if the problem is in the hip and not due to HNP. Pain produced by this test is called Patrick’s Sign. If found, a hip evaluation (X-rays, MRI) is indicated.