Spondylolysis is characterized by a defective (separated) pars interarticularis, the bony bridge joining the superior and inferior articular processes of the vertebrae. The pars defect usually results from congenital dysplasia (patients aged <20 years), degenerative disease (patients aged >40 years), and/or trauma (e.g., high-impact repetitive sports such as gymnastics or weight lifting).
Spondylolysis describes a fracture of the pars interarticularis, which is located along the posterior arch of the bony spine. These fractures can be unilateral or bilateral; a bilateral presentation makes 80% of the cases. These fractures are caused by activity fatigue or acute overload. More than 90% of these fractures occur at the L5 vertebrae. Spondylolysis is the common cause of back pain in young athletes. Gymnasts, football players, wrestlers, dancers, and any young athletes who perform repetitive twisting and extension motions are at risk for back injury. Fatigue fractures in athletes commonly occur during growth spurts. Stress along the pars interarticularis will cause underlying spondylolysis (also known as “pars defect”). Spondylolysis is commonly asymptomatic, with diagnosis commonly found incidentally. Pain is often intermittent and can refer to the buttock or posterior thigh. Extension and rotation of the lumbar spine will commonly reproduce the pain. Tight hamstrings can usually be found on examination.
AP and lateral x-rays are the initial visual modality to rule out fracture. If the x-rays are clear but there is still clinical suspicion of a fracture, an MRI or single-photon emission computed tomography (SPECT) bone scan can be performed. A CT scan can be performed but it encompasses exposure to high doses of radiation. Those with bilateral spondylolysis may also develop spondylolisthesis, or shifting of the one lumbar vertebra over the other. With uncomplicated cases (without radiculopathy, factures, etc.) it is advised to limit inciting activity for 2 to 4 weeks. This simple plan is very effective for most cases. For athletes unwilling to rest, bracing during activity can be utilized. NSAIDs are recommended for pain management. Those with nerve injury must receive a consultation with a spine specialist. On physical exam, testing for hypermobility should be strongly considered. Patients with a grade 2 or higher (spondylolisthesis is scored at grade 1 to 5) should be evaluated by a surgeon. After treatment, once the patient is pain free, slow reintegration back into sports should be undertaken.