Low back pain in pediatric athletes with unilateral tracer uptake at the pars interarticularis on single photon emission computed tomography

Study Design. Retrospective clinical study with radiographic and medical chart review. Objective. To study the clinical characteristics and outcome of pediatric athletes with low back pain and unilateral tracer uptake on single photon emission computed tomography (SPECT) at the pars interarticularis but no defect on radiographs. Summary of Background Data. Some pediatric athletes with low back pain have no findings on plain radiographs but a unilateral SPECT uptake at the pars interarticularis. However, little is known about these patients. Methods. Twenty-two pediatric athletes who had low back pain with increased tracer uptake on SPECT unilaterally at the pars interarticularis but no defect on plain radiograph were evaluated. The following criteria were used for evaluation: age, male-to-female ratio, duration of symptoms, vertebral level, and presence of spina bifida occulta or scoliosis. Results. The average age was 12.3 +/- 2.5 years. The male-to-female ratio was 1.2:1. The average duration of symptoms was 21 +/- 23 weeks. Nineteen (86%) had increased uptake at L5. Six (27%) had spina bifida occulta and 8 (36%) had scoliosis. Eighteen (82%) patients showed an excellent outcome. The patients who presented with a longer history of symptoms or a concomitant spina bifida occulta had an increased risk of having occasional aching with vigorous activity when compared with the patients who did not (P < 0.05). Conclusions. Athletes who have low back pain and increased tracer uptake unilaterally at the pars interarticularis on SPECT are younger than those previously reported patients with spondylolysis proven by a defect on radiographs. Some of these lesions do progress to "frank" spondylolysis seen on radiographs, but favorable clinical outcomes from nonoperative treatment can be expected. Patients with a longer pain history or concomitant spina bifida occulta may need careful follow-up because they are at increased risk of having occasional low back pain.