Spondylolysis (Pars fracture)

Spondylolysis is a defect or stress fracture in the pars interarticularis of the vertebral arch, commonly affecting the lower lumbar vertebrae. This condition is prevalent among young athletes involved in sports that exert repetitive stress on the lower back, such as gymnastics, football, and weightlifting where there is back extension. Although often asymptomatic, spondylolysis can lead to significant discomfort and complications like a pinched nerve (radiculopathy) or unstable spine (spondylolisthesis) if left untreated.

Key Takeaways

• Spondylolysis primarily affects the lower lumbar vertebrae (lumbar 4 or lumbar 5) and is common in young athletes engaged in sports that involve repetitive back extension stress on the lower back (e.g weight lifting, gymnastics, tennis, diving).
• Diagnosis often requires x-rays (including flexion extension views), CT scan and MRI scans of the lumbar spine. Radionuclide technetium scans can also be done to assess if the pars fracture is recent.
• Treatment can range from non-surgical interventions (bracing) to surgical procedures depending on the severity of the condition.

Etiology and Pathophysiology of Spondylolysis

Spondylolysis is a unilateral or bilateral bony defect in the pars interarticularis or isthmus of the vertebra. It most commonly affects the lumbar vertebrae, but has also been reported in the cervical and thoracic regions. The term derives from the Greek words spondylos (vertebra) and lysis (defect). It can cause a slipping of the vertebra, in which case the term spondylolytic spondylolisthesis is used.

Clinical Presentation and Diagnosis

Common Symptoms

Spondylolysis is commonly asymptomatic. However, when symptoms do occur, they often include low back pain, which may be exacerbated by activities involving lumbar spine extension or rotation. Patients may also experience paraspinal spasm and tight hamstrings. In some cases, pain may radiate to the buttocks or legs if the exiting lumbar nerve roots are pinched. This can occur if there is forward slippage of the lumbar vertebrae or if there is scar tissue forming under the pars fracture.

Diagnostic Imaging Techniques

The diagnosis of spondylolysis can be challenging as clinical tests have limited value. Diagnostic imaging is crucial for accurate identification. Plain x-rays, including lateral, anteroposterior, and oblique views, are typically the first step. Computed tomography (CT) scans provide detailed images of the bony structures and are highly sensitive for detecting pars defects. Magnetic resonance imaging (MRI) can be useful for assessing soft tissue and nerve involvement. In some cases we will do a technetium bone scan to assess if the pars fracture is recent. If it’s recent, there is still a chance for bony healing with the appropriate treatment.

Differential Diagnosis

The differential diagnosis for spondylolysis includes other causes of low back pain such as lumbar disc herniation, spinal stenosis, and muscle strain. It is essential to rule out these conditions to ensure an accurate diagnosis. A thorough clinical evaluation and appropriate imaging studies are necessary to differentiate spondylolysis from other spinal disorders.

Management and Treatment Options

Non-Surgical Interventions

Conservative treatment is often sufficient for symptomatic cases and includes the use of NSAIDs for pain relief, cessation of aggravating activities, and physiotherapy to strengthen the lumbar core muscles. The application of a spinal brace may also be recommended to prevent motion at the injured pars and facilitate bony repair. In some cases, targetted pars injections may be utilized to manage pain or confirm the source of pain is from the pars fracture.

Surgical Techniques

Surgical intervention is considered when non-surgical methods fail to provide relief or when there is progression of slippage, significant subluxation, or neurological symptoms. The primary goals of surgical treatment are to stabilise the pars fracture and bone grafting of the pars defect. Several techniques have been described:

• Pedicle screw with hooks
• Pedicle screw with rod (Smiley technique)
• Cannulated screws (Buck’s technique)
• Wiring technique

Success rates vary from 80% to 90% at 6 months review.

With minimally invasive techniques and image guidance, the most promising technique is the Buck’s technique using a navigated cannulated screw and an endoscopic or tubular approach to bone grafting the pars fracture site.

Post-Treatment Outcomes

Post-treatment outcomes for spondylolysis vary based on the intervention used. Patients who undergo successful fusion with normal sagittal alignment generally experience favorable clinical outcomes. However, complications such as pseudarthrosis and loss of fixation, can occur. Long-term follow-up is essential to monitor for potential issues and ensure optimal recovery.