Review Question - QID 218728

This patient has clinical findings suggestive of spondylolysis/spondylolisthesis. The best initial radiographic studies are anteroposterior and lateral radiographs alone (Answer 5).

Spondylolysis and spondylolisthesis are common causes of back pain in adolescent athletes. This constellation of pathology affects up to 6-7% of the overall population (prevalence) by the age of 6. While it may be an incidental finding, it can be implicated in up to 47% of low back pain complaints in this population. The most commonly affected anatomic location is the pars intraarticularis of L5. In an acute spondylolysis, initial radiographs may be negative and additional imaging may be needed. Risk factors for the development of these pathologies include contact sports and sports which require repetitive lumbar hyperextension. If the pars fracture becomes complete bilaterally, it can occasionally lead to anterolisthesis of L5 relative to S1. In addition, a higher sacral table index, pelvic incidence, sacral slope, and lower sacral table angle are patient-specific risk factors.

The best initial radiographic studies are anteroposterior (AP) and lateral radiographs of the lumbar spine. A defect in the pars is visible on up to 80% of lateral radiographs. Recent data has demonstrated that oblique radiographs do not provide additional diagnostic information, in addition to exposing the patient to additional radiation. It is important to recognize that radiographic evidence of spondylolysis may be incidental, and does not always correlate with the presence of pain. Furthermore, not all patients with acute spondylolysis will have evidence of spondylolisthesis.

Tofte et al. provide a systematic review of imaging pediatric spondylolysis. Their study ultimately pooled data from 10 papers. Based on efficiency, cost-effectiveness, and low radiation exposure, the authors recommend two-view plain films to be the best initial radiographic study. The authors state that patients with unusual presentations or refractory courses may benefit from MRI or CT, but there is a lack of rigorous studies from which to draw definitive recommendations.

Miller et al. provide a retrospective review of imaging modalities for low back pain in children. Their study included 2,846 patients with an average age of 14.3 years. The authors state that for spondylolysis, two-view plain films are often diagnostic and that oblique views do not add significant value. The authors caution that while advanced imaging may increase diagnostic accuracy, it comes at the expense of additional cost and radiation exposure.

Incorrect Answers:
Answer 1: The most common location for pediatric spondylolysis is the pars intraarticularis of L5.
Answer 2: Spondylolysis/spondylolisthesis is a common cause of low back pain in adolescents
Answer 3: MRI is as sensitive and specific as single photon emission computer tomography (SPECT), and avoids additional radiation exposure
Answer 4: The addition of oblique radiographs to anteroposterior and lateral radiographs confers no additional diagnostic information