Three stages of injury to the pars interarticularis—the portion of the lower spine that joins together the upper and lower joints—exist:

  • Stress reaction
  • Fracture (spondylolysis)
  • Slippage (spondylolisthesis)—when the bone defect left by the fracture leads to one vertebra slipping onto another.

Spondylolysis and Spondylolisthesis

  • Where: Most commonly in the lumbar spine at the lowest vertebra, L5.
  • When: Most often in adolescence and young adulthood. Adults with spondylolisthesis rarely have progression of the slipping of the vertebrae.
  • Symptoms: Many people with spondylolysis and spondylolisthesis never become symptomatic and live their lives normally. But when symptoms arise, they may include the following:
    • Lower back pain
    • Stiffness
    • Hamstring muscle tightness
    • Leg pain

Imaging Evaluation

  • X-rays: Used most often to reveal the presence of spondylolysis
  • CT scans: Used to evaluate pondylolysis if x-rays are not clear
  • Bone scans: Used more often in children and young adults, and may show increased bone activity at the site of the spondylolysis.
  • Magnetic resonance imaging (MRI) scans: Used to evaluate leg pain and identify possible areas of stenosis or narrowing of space around the spinal nerves. Most common when a slip (spondylolisthesis) occurs.

Treatment Options

The goals of treatment are relieving the pain, decreasing spasms and restoring spinal flexibility. Treatment is customized based on the severity of symptoms.

Nonoperative Treatment

Nonoperative treatment includes:

  • Anti-inflammatory drugs
  • Physical therapy
  • Brace wear
  • Truncal core muscle strengthening (pilates or yoga)

Operative Treatment

Operative treatment—explored if pain, spasm, or slippage increases despite conservative management—includes:

Spinal Fusion

Fusing the fifth lumbar (lower back) vertebra to the sacrum (tailbone) is typically the first choice.

  • Vertebrae “glued together” by removing loose bony fragments and placing bone graft.
  • A plastic or metal cage packed with bone matter may be placed in the disc space to increase the likelihood of fusion.
  • Depending on the degree of the slippage, the bones may be realigned to various degrees—restoring stability and ensuring no pressure is placed on the nerves.

Pars Repair

Bones are not fused together. The rigid or problematic bone is removed; 2 sides of the fracture are stabilized to restore normal anatomy.

  • Rarely successful in adults 20 years and older
  • Not recommended if there is slippage (spondylolisthesis) or moderate or severe disc degeneration at that vertebra level.


Adapted from