A healthy spine provides the main support for the body, allowing a person to stand and sit upright, walk, bend, and twist. Muscles, ligaments, tendons, and bone all contribute to a strong spine and protect the spinal cord. A side view of the normal spine shows it has some curves to it to help it withstand impact and force and to maintain balance. In particular, the neck (cervical spine) has a slight C-shaped inward curve to it, as does the low back (lumbar spine). This C-shape is known as lordosis. The mid-back (thoracic spine) and sacral areas have a reverse (outward) C-shape, which is called kyphosis. Both lordosis and kyphosis are normal. (It is important to note that the exaggerated, problematic curve that is officially known as hyperkyphosis is sometimes referred to simply as kyphosis. Hyperkyphosis is not the same as normal kyphosis.) From the front or back, a healthy spine appears straight.
Spinal deformity occurs when the curves of the spine differ from the normal, gentle S-shape seen from the side, or the straight line down the back of a normal spine. Spinal deformities may lead to symptoms that include pain, weakness, numbness, tingling, loss of function, and pulmonary and cardiac problems.
A few types of spinal deformities that can be successfully treated with spinal surgery are scoliosis, kyphosis, and spondylolisthesis.
Reviewed by: Kai-Ming Fu, MD, PhD
Last Reviewed/Last Updated: August 2021
Illustrations by Thom Graves, CMI