The lumbosacral joint, also called L5-S1, is a term used to describe a part of the spine. L5-S1 is the exact spot where the lumbar spine ends and the sacral spine begins. The lumbosacral joint ...

Another cause of low back pain is a strain of the SI (sacroiliac) joint. Pain and tenderness are usually located on one side of the sacrum, often radiating into the thigh. Patients with SI strain ...