• Paget's disease of bone. Paget’s disease is a chronic disorder in which excessive breakdown and formation of bone causes the bones to become enlarged, misshapen and weakened. The disease usually does not affect the entire skeleton, but just one or a few bones. The vertebrae are among the bones most commonly affected by Paget's disease.

Learn more about Paget's Disease of the Bone from the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

• Sciatica. This is inflammation of the sciatic nerve. The largest nerve in the human body, the sciatic nerve runs from the lower part of the spinal cord, through the buttock and down the back of the leg to the foot. The most common causes of sciatica include compression of the nerve where it exists the spine by a herniated disc, or a rupture of one of the structures that cushions the vertebrae in the spine. Sciatica may be felt as a sharp or burning pain that radiates from the hip. It may also be accompanied by low back pain.

Learn more about sciatica from the American Academy of Orthopaedic Surgeons.

• Scoliosis. Instead of running straight up the center of the back, a spine with scoliosis twists to one side. Scoliosis can be classified as true (meaning it has to do with abnormal development of the spine) or functional (meaning its cause is not directly related to the spine). Functional scoliosis may occur when a discrepancy in leg length causes the pelvis to tilt to one side to compensate. The cause of true scoliosis is largely unknown, although doctors suspect that it may be the result of imbalanced growth in childhood.

Learn more about scoliosis from the American Academy of Orthopaedic Surgeons.