What it is
Spondylolisthesis is forward slippage of one vertebra on the one beneath it. The two common forms behave differently: degenerative slips occur in older adults as the facet joints and disc wear, usually at L4–L5; isthmic slips follow a stress fracture in part of the bony arch, often from adolescence, usually at L5–S1.
The degree is graded by how far the vertebra has moved. Most are low grade and remain so.
Symptoms
- Back pain, often worse with standing and extension
- Leg pain or heaviness from narrowing of the nerve exits
- Hamstring tightness and a change in posture or gait in higher-grade slips
- Many slips cause no symptoms at all and are found incidentally
How it is diagnosed
Standing X-rays show the slip; flexion and extension views show whether it moves, which is the question that matters most. MRI shows the nerve compression and the state of the disc. A CT can define a bony defect where an isthmic slip is suspected.
Non-surgical treatment
Physical therapy focused on core and hip strength, activity modification, anti-inflammatory medication and injections. Most low-grade degenerative slips are managed this way successfully and indefinitely.
When surgery is considered
Persistent leg symptoms from nerve compression, demonstrable instability on flexion and extension films, or progression of the slip. The operation decompresses the nerves and, where the level is unstable, stabilizes it. Whether that needs a fusion, and by which approach, is a decision Dr. Long makes from your films and your symptoms rather than from the diagnosis alone.