Isthmic Spondylolisthesis

Facet joints are critical for overall spine alignment. Their primary function is to provide stability to the spine while allowing for controlled motion. This controlled motion is essential for bending, twisting, and turning. However, they are also a common site for degenerative changes and injury leading to pain and dysfunction. In isthmic spondylolisthesis, the fracture of the pars interarticular causes instability in the facet joints, which accelerates facet joint deterioration.

The primary cause is instability in the pars interarticularis due to a defect or stress fractures that often result from stress or trauma. Stress fractures can heal and fracture repeatedly due to repetitive motions. This is commonly observed in athletes involved in sports that place significant stress on the lower back, such as golf, baseball, gymnastics, weightlifting, and football. However, isthmic spondylolisthesis can occur due to congenital and degenerative causes.

Most cases do not cause symptoms. However, if there are symptoms, the primary symptom of chronic spondylolisthesis is back pain, with and without leg pain. In most cases, symptoms are chronic. When spondylolisthesis occurs due to trauma or metastatic tumors, patients can present with neurological deficits, including loss of bowel and bladder function. If the displacement compresses nerve roots, it can also cause radiating pain, numbness, tingling, or weakness in the lower extremities. Isthmic spondylolisthesis can also cause spinal stenosis and accelerate disc degeneration.

Diagnosis of isthmic spondylolisthesis generally involves a combination of patient history, physical examination, and imaging studies. Radiographs (X-rays) of the spine are typically the first-line imaging used, as they clearly show the degree of slippage. The severity of the slip in isthmic spondylolisthesis is graded on a scale from I to V based on the percentage of slippage. A CT scan of the lumbar spine is the definitive study to assess the pars defect. An MRI is the choice to evaluate the soft tissue structures. It is typically needed for patients who fail conservative treatments and for planning surgery.

Typically, isthmic spondylolisthesis with low back pain is managed conservatively and includes:

• Activity modification
• NSAIDS for pain
• Muscle relaxers
• Physical therapy
• Steroid injections

In cases where conservative management fails or there are significant neurological symptoms, surgical intervention may be required. Surgical options may include decompression of the nerve roots and stabilization of the affected vertebrae through spinal fusion.