Each segment of the crest is connected by small articular synovial joints posterior to the vertebral body, intervertebral discs between the vertebral bodies, and the soft tissues (ligaments and muscles) surrounding the crest, thus ensuring that each vertebra of the crest is in a correct sequence. This configuration facilitates the movement of the crural column while protecting the crural medulla and nerve heel. If the connections between the vertebrae break (isthmus disconnections), or if the intervertebral structures become degeneratively unstable, this can cause the vertebrae in this area to shift forward, a condition known as vertebral slippage. Since each part of the crest is tasked with supporting the body, the absence of any one part means that the other parts have to work harder. As a result, they can accelerate damage and lead to further progression of the slippage. The two most common types of lumbar spondylolisthesis are the “developmental” and “degenerative” types. Developmental spondylolisthesis tends to involve dysplasia or deformity of the crestal spine and usually occurs at a young age, often in adolescents or young adults. In contrast, degenerative slippage involves the loss of a previously normal crestal spine. These slippages may not become apparent until the 50s and are often associated with spinal stenosis and arthritis. Symptoms and diagnosis: A slipped vertebral lift can cause changes in the line of force in the crestal column, leading to conditions such as back and leg pain, as well as numbness or weakness in the legs. The severity of these symptoms depends on the severity of the slippage and the degree of spinal stenosis. In addition to CT and/or MRI scans, X-rays may be diagnostic. While some slipped crestal vertebrae themselves remain unchanged, others will progressively deteriorate. Treatment: Initial treatment of low back pain due to a slipped crest usually includes rest, medication, physical therapy, and/or bracing. When symptoms do not respond to non-surgical treatment or the slippage worsens, reconstructive surgery may be done to stabilize (fuse) the crestal vertebrae and decompress the crestal nerve.