Lumbar Spondylolisthesis

Spondylolisthesis is when one vertebra in your lower back slips forward on the one below it. There are two main types. Degenerative spondylolisthesis is the more common version — the disc and small joints between vertebrae wear out enough that the upper vertebra drifts forward, typically at the L4–L5 level in older women. Isthmic spondylolisthesis comes from a stress fracture through a small bony bridge in the back of the vertebra (the pars interarticularis) that lets the vertebra slip forward — typically at L5–S1 in young athletes. Severity is graded 1 through 4 based on how far the slip has progressed.

Symptoms range from nothing at all (often found by accident on an X-ray for some other reason) to severe low back pain with leg pain or heaviness that comes on with walking — when the slip has narrowed the canal enough to compress the nerves.

Many people with a low-grade slip have no symptoms at all — the slip is found by accident on an X-ray taken for something else. When symptoms do develop, the most common is a deep, aching low back pain that worsens with standing and walking and eases when you sit down or lean forward. Tight hamstrings are a frequent companion finding that your surgeon may pick up on exam.

If the slip has narrowed the spinal canal enough to compress nerves, you may notice aching, heaviness, or numbness in one or both legs that comes on with walking and fades when you sit — a pattern called neurogenic claudication. Higher-grade slips can produce a visible step-off in the lower back and a shortened, waddling gait. Pain that travels down a specific nerve path in the leg suggests the slip is pinching a nerve root at that level.

Standing side-view X-rays measure how far the vertebra has slipped. Bending-forward and bending-backward X-rays show whether the slip moves with motion (a sign of instability). MRI shows whether nerves are being compressed by the slip; CT defines the bony anatomy for any surgical planning.

Surgery helps only a small minority of spine patients — usually those with a specific structural problem plus a nerve issue that isn’t getting better with a structured non-operative trial. When that step is genuinely warranted, OSI coordinates it the same way we coordinate every other part of your care: imaging, records, and the handoff are handled for you, so no part of the process falls on your shoulders.

Emergency. Bilateral leg weakness, saddle numbness, or loss of bladder or bowel control is a surgical emergency — go to the nearest emergency department rather than waiting for a clinic appointment.

External patient-education references and related OSI pages for additional background:

• Britannica — Vertebral column
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language