Ankylosing spondylitis is a degenerative form of spinal arthritis that causes chronic pain and stiffness in the lower back, hips and buttocks, explains WebMD. The condition frequently triggers excessive bone growth throughout the spine, causing sections of bone to fuse together and restrict bodily movements.
As of 2015, ankylosing spondylitis is incurable, and its systemic nature means the arthritic inflammation can spread to other body areas, such as the eyes, heart and lungs, according to WebMD. The condition often originates at the sacroiliac joints, the lower spinal bones that connect to the ilium joint, which is the uppermost pelvic bone.
Spinal muscular atrophy, or SMA, is a hereditary degenerative condition that causes spinal cord nerve cells to deteriorate, leading to impaired motor functions, states the National Institute of Neurological Disorders and Stroke. The lower motor neurons in the brain are unable to send normal signals to the muscular system, resulting in weakened muscle tissue and involuntary reflex movements. Depending on the type of SMA, individuals lose control of essential muscle movements, such as speaking, eating, breathing and walking.
Degenerative disc disease occurs normally during the aging process and involves the deterioration of the soft discs that cushion the vertebrae in the spine, notes WebMD. Spinal discs naturally break down over time and lose fluid, reducing their shock absorption and causing vertebrae to press closer together. Increased spinal pressure may cause the bones to growth tiny projections, known as spurs, which can endanger the spinal cord and surrounding nerves.