The vertebral column (spine) is made up of bones called vertebrae, which have cartilage discs between them. These intervertebral discs protect the vertebrae and make the spinal column flexible. A disc is made of connective tissue and has a stronger outer fibrous outer part and a softer jelly-like center called the nucleus pulposus. The spinal cord (continuation of the brain below the skull), lies in the centre of the vertebral column. Nerves from the spinal cord come out from between the vertebrae to take and receive messages to various parts of the body.
A slipped disc is when the soft part of the disc bulges through the circle of connective tissue and this may then press on the spinal cord or the nerve roots. A prolapsed disc usually occurs when excess pressure is suddenly put on the disc (sudden heavy lifting). Factors that may increase the risk of developing a slipped disc include: jobs involving lots of lifting or sitting, weight bearing sports and increasing age (a disc is more likely to prolapse if it has become weaker, which occurs with increasing age). The most common site for a disc prolapse is the lower back (lumbo-sacral region). One-fifth people with slipped disc are asymptomatic.
Treatment is generally conservative (bed rest, analgesics, physiotherapy etc.) with surgery being reserved for patients with symptoms of spinal cord or nerve compression. The earlier practice of prolonged rest until the pain eased is no longer tenable as several studies have shown that patients are more likely to develop chronic (persistent) back pain with continued rest as compared to those who are active. Prolonged use of a belt is not advocated for similar reason.