Spondylolisthesis

The spine is made up of bones called vertebrae stacked on top of one another. In spondylolisthesis, one vertebra slips forward out of line over the vertebra below it. This most often happens low down in the spine, in the lumbar (lower back) region.

The amount of slip varies from slight to more pronounced, and doctors grade it to guide treatment. Many people with a mild slip have few or no symptoms, while a larger slip can cause back pain and, if it narrows the space around the nerves, leg symptoms.

The most common symptom is lower back pain, which may be worse with activity, standing, or bending backward, and eased by rest. There may be stiffness and tight hamstring muscles at the back of the thighs.

If the slip narrows the space where the nerves run, it can cause pain, numbness, tingling, or weakness that spreads into the buttock or leg (sciatica). Some people have no symptoms at all, and the slip is found by chance on an X-ray taken for another reason.

In children and younger, active people — particularly those doing sports that repeatedly arch the back, such as gymnastics or cricket — spondylolisthesis often follows a small stress fracture in part of the vertebra (called spondylolysis), which allows it to slip.

In older adults, the most common cause is degenerative: age-related wear of the discs and small spinal joints loosens the connection between vertebrae, letting one slip forward. Less commonly, it is present from birth, follows an injury, or is due to another bone condition.

A doctor asks about your symptoms and examines your back and legs, checking movement, nerve function, and hamstring tightness. Spondylolisthesis is confirmed with X-rays, which show the slip and allow it to be graded by how far the vertebra has moved.

If you have leg symptoms or surgery is being considered, an MRI scan shows the discs and nerves in detail and helps explain any nerve compression. A CT scan is sometimes used to look closely at the bone.

Most people are treated without surgery. This usually includes a period of activity modification, pain relief, and — importantly — physiotherapy to strengthen the core and back muscles, improve flexibility, and support the spine. Many people settle well with this approach, and steroid injections are sometimes used for troublesome nerve pain.

Surgery is considered when symptoms are severe and do not improve, when there is significant or worsening slip, or when nerves are compressed and causing leg weakness or persistent pain. The operation typically decompresses the trapped nerves and fuses the affected vertebrae to stabilize the spine.

The outlook is generally good. Many people manage well with physiotherapy and activity changes and avoid surgery altogether, and when surgery is needed for severe or nerve-related cases, it is usually effective at relieving symptoms and stabilizing the spine.

It cannot always be prevented, but keeping the core and back muscles strong, using good technique in sport, and building up back-arching activities gradually may reduce the risk in younger people. Staying active and maintaining a healthy weight supports the spine in later life.