Isthmic spondylolisthesis

Isthmic spondylolisthesis is a condition of the spine that occurs when a vertebra (one of the interlocking bones that forms the spinal column) slips forward (anterolisthesis) or backward (retrolisthesis) on the vertebra below. This type of spinal instability occurs because of a fracture in a part of the vertebra called the pars interarticularis that connects each of the facet joints on the posterior (towards the back) of the spinal segment. This spinal defect can occur in up to four percent of the population. Isthmic spondylolisthesis most commonly affects the lumbar (lower back) section of the spinal column.


The primary causes of isthmic spondylolisthesis include:

  • Genetic bone malformation – abnormal formation of bones in the vertebrae.
  • Accumulated physical stress – for people with weak or malformed bones, physical stress can cause the vertebral structures to break and slip.
  • Repetitive postures or movements – continuous heavy lifting, twisting and back bending can cause small fractures and lead to the slipping of the pars interarticularis bone.
  • Sports – weightlifters, football players and gymnasts are especially susceptible to isthmic spondylolisthesis due to the amount of stress their activities place on their bodies on a daily basis.


Though isthmic spondylolisthesis can cause spinal instability, not all patients experience pain from this condition. Symptoms of isthmic spondylolisthesis can include:

  • Low back pain – the most common symptom of isthmic spondylolisthesis. Pain often worsens after exercise or during activity that stresses the lower back.
  • Sciatica – pain, weakness, numbness or tingling in the leg caused by injury or pressure on the sciatic nerve.
  • Muscle spasms – sudden, involuntary contractions of a muscle as a result of nerve irritation.
  • Leg weakness – It is common for any condition resulting in spinal instability to cause weakness in the legs.
  • Decreased range of motion in the lower back – stiffness from isthmic spondylolisthesis will significantly decrease range of motion in your lower back.
  • Loss of bowel and bladder control – can result from a severe compression of the nerves.
  • Tight hamstring muscles – These large muscles in the back of the thigh are susceptible to stress from any spinal deformity.
  • Irregular gait – It is not uncommon to limp or walk abnormally due to sciatica, leg weakness, tight hamstring muscles and any other symptoms of isthmic spondylolisthesis which directly affect the legs.


Initial treatment for isthmic spondylolisthesis is conservative and can include rest, anti-inflammatory medications, therapy, cortisone injections and bracing. For more severe cases of isthmic spondylolisthesis, surgery to stabilize the spine may be necessary and will include spinal fusion with spinal instrumentation.

The multidisciplinary team of spine experts at Northwell Health Orthopaedic Institute treats isthmic spondylolisthesis as well as a broad range of spine conditions that can occur at any stage of life.

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