University of Virginia School of Medicine, Charlottesville

A 15-year-old high school football player presented with low back pain on the right side. The pain started about 1 month earlier after he was tackled while jumping, with his arms and back fully extended to catch the football. The pain remained localized to the right lower back, worsened with lateral flexion, and was relieved only slightly with ibuprofen. He also had discomfort while sleeping. He denied weakness, numbness, tingling, weight loss, and fevers.

The teen was well-appearing, in no distress, and afebrile. He had tenderness and tightness on palpation of the right lower lumbar spine and paraspinal muscles. He had right lower back pain when he stood on his right leg with his left hip flexed and his back hyperextended (the stork test) but full strength and range of motion of his back and right hip.

Plain films of the lower spine showed an image of a Scotty dog (A and B, marked). The collar of the dog indicates a fracture of the pars interarticularis, consistent with spondylolysis.

Spondylolysis is a common cause of back pain in the adolescent athlete and is almost exclusively found in the pediatric population. It occurs most often at the L5 vertebral level and occasionally at L4. The condition is thought to be caused by mechanical stress of the trunk with repetitive flexion, hyperextension, and trunk rotation. Athletes participating in football, gymnastics, and weight lifting and children carrying heavy backpacks are at risk.1

Patients with spondylolysis have pain that worsens with activity and hyperextension.2 Neurological and systemic symptoms are rare and if present should prompt evaluation for an alternative diagnosis.3

The choice of diagnostic imaging is controversial. Although plain radiography has low sensitivity in diagnosing spondylolysis, it can be useful, as it was in this case. If plain radiographs are negative, single-photon emission CT has the highest sensitivity for spondylo-lysis. MRI may show bone marrow edema associated with spondylolysis and is more useful for evaluating other causes of back pain, such as disk disease and spinal tumors.

The recommended treatment of spondylolysis is rest for at least 3 to 6 months.4 Physical therapy is useful after the pain has resolved. If conservative management for up to a year fails, then surgical intervention can be considered.1,3 About 70% to 100% of patients who undergo surgery have resolution of symptoms.4

This patient refrained from sports participation during the spring and summer and initiated physical therapy but did not continue it. He returned to clinic with recurrence of back pain after the start of football season. Follow-up films at 1 year showed persistence of the pars interarticularis fracture. Physical therapy was again prescribed.