The L5-S1 spinal motion segment, also called the lumbosacral joint, is the transition region between the lumbar spine and sacral spine in the lower back. In this region, the curvature of the spine changes from lumbar lordosis (forward curve) to sacral kyphosis (backward curve).
The lumbosacral joint may develop wear-and-tear arthritis (osteoarthritis) over time due to its high load-bearing function. Facet joint pain may also occur due to due to inflammatory conditions, such as rheumatoid arthritis or degenerative spondylolisthesis.
