Facet disease is caused by the cartilage in the joints being worn down as a result of wear, aging, injury, or misuse. This type of injury to the spine can be attributed to arthritis of the spine, work, over-use, or an accident. Facet disease occurs when a facet joint degenerates. While this can take place at any level of the spine, it most commonly affects the lumbar (lower spine) region. Another possible result of facet disease is spondylolisthesis, which occurs when a vertebra slips forward in relation to an adjacent vertebra, usually in the lumbar spine.