Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

What spinal condition involves a separation of the pars interarticularis of the vertebral arch?

1. Spondylolisthesis

2. Spondylolysis

3. Disc herniation

4. Spinal stenosis

The correct answer is: Spondylolysis

The condition that involves a separation of the pars interarticularis of the vertebral arch is known as spondylolysis. This specific defect occurs often due to a stress fracture or defect in this particular area of the vertebra, which can be a result of repetitive stress or trauma, commonly seen in athletes who engage in activities that require hyperextension of the spine. In spondylolysis, the separation can lead to instability of the vertebral segment, which may subsequently progress to spondylolisthesis, where one vertebra slips over the one below it. Understanding this distinction is crucial, as spondylolysis itself is the precursor to other conditions but is distinct from spondylolisthesis, which specifically refers to vertebral slippage. Other conditions mentioned, such as disc herniation, involve the intervertebral discs and are not related to the pars interarticularis. Similarly, spinal stenosis refers to a narrowing of the spinal canal and does not involve the separation of the pars interarticularis. Hence, spondylolysis is the correct answer regarding the condition defined by this separation.