The lumbar vertebra consist of a body, pedicle, lamina, pars interarticularis, transverse process, spinous process and superior and inferior articular facets, which form joints that link the vertebrae together. When examining the vertebra, the pars interarticularis is the bony segment between the superior and inferior articular facet joints located anterior to the lamina and posterior to the pedicle. Separation of the pars interarticularis occurs when spondylolysis is present in the spinal column.Spondylolysis is typically caused by a stress fracture of the bone, and is especially common in adolescents who over-train in activities. The pars interarticularis is vulnerable to fracture during spinal hyperextension, especially when combined with rotation, or when experiencing a force during a landing. This stress fracture most commonly occurs where the concave lumbar spine transitions to the convex sacrum (L5-S1). A significant number of individuals with spondylolysis will develop spondylolisthesis, which is true for 50-81% of this population. Diagnosis
There are several imaging techniques used to diagnose spondylolysis. Common imaging techniques include X-ray, MRI, Bone Scintigraphy (Bone Scan), and Computed Tomography (CT Scan). X-Ray
X-rays (electromagnetic radiation) are projected through the body to produce an image of its internal structures. The radiation is more attenuated (absorbed) by the denser tissues of the body (i.e. bone) than the softer tissues (i.e. muscles, organs, etc) creating a picture composed of shades of grey ranging from white to black. A vertebra with a fracture or defect of the pars interarticularis will have a dark mark through this region of bone.
To compensate, the large torque producing global muscles are used to stabilize the spine.In one study, patients are taught to train the co-contraction of deep abdominal muscles and lumbar multifidus in static postures, functional tasks and aerobic activities. This technique was shown to reduce pain and functional disability when compared to other conservative treatments. These results also had a long- term effect in reducing levels of pain and functional disability. This is because motor programming eventually became automatic, and conscious control was no longer needed to contract the deep abdominal muscles during activities. Activity restriction
Activity restriction of spondylolysis is advised for a short period of time once the patient becomes symptomatic, followed by a guided physical therapy program. Once spondylolysis has been diagnosed, treatment often consists of a short rest period of two to three days, followed by a physical therapy program. There should be restriction of heavy lifting, excessive bending, twisting and avoidance of any work, recreational activities or participation in sport that causes stress to the lumbar spine. Activity restriction can help eliminate and control a patients symptoms so they are able to resume their normal activities. Activity restriction is most commonly used in conjunction with other rehabilitation techniques including bracing. Bracing
Acute spondylolysis is most commonly treated through the use of an antilordotic brace (Boston brace) to control and limit spinal movement, and reduce stress on the injured spinal segment. Bracing immobilizes the spine in a flexed position for a short period to allow healing of the bony defect in the pars interarticularis.