Pars interarticularis

Pars interarticularis is a small segment of bone that connects the superior and inferior articular processes of the vertebra. It is a critical structure in the vertebral column and plays a significant role in the stability and movement of the spine.

Anatomy

The pars interarticularis is located in the posterior part of the vertebra, specifically in the lumbar vertebrae and cervical vertebrae. It is part of the vertebral arch and is situated between the lamina and the pedicle of the vertebra. The pars interarticularis can be visualized on an oblique radiograph of the spine, where it appears as the "neck" of the "Scotty dog" silhouette.

Function

The primary function of the pars interarticularis is to provide structural support and stability to the vertebrae. It helps to resist the shear forces that act on the spine during movement and weight-bearing activities. The integrity of the pars interarticularis is essential for maintaining the alignment and function of the vertebral column.

Clinical Significance

A defect or fracture in the pars interarticularis is known as spondylolysis. This condition is commonly seen in athletes and individuals who engage in activities that involve repetitive hyperextension of the spine, such as gymnastics, weightlifting, and football. Spondylolysis can lead to spondylolisthesis, a condition where one vertebra slips forward over the one below it, causing pain and potential nerve compression.

Diagnosis

The diagnosis of a pars interarticularis defect is typically made through imaging studies. X-rays, particularly oblique views, are commonly used to identify the defect. Computed tomography (CT) scans and magnetic resonance imaging (MRI) can provide more detailed images and help assess the extent of the injury and any associated soft tissue damage.

Treatment

Treatment for a pars interarticularis defect depends on the severity of the condition and the symptoms experienced by the patient. Conservative treatments include rest, physical therapy, and nonsteroidal anti-inflammatory drugs (NSAIDs) to manage pain and inflammation. In cases where conservative treatment is not effective, surgical intervention may be necessary to stabilize the spine and relieve symptoms.

See Also

• Vertebral column
• Spondylolysis
• Spondylolisthesis
• Lumbar vertebrae
• Cervical vertebrae