Quantitative assessment with SPECT imaging of stress injuries of the pars interarticularis and response to bracing

The evaluation and management of acute spondylolysis remains unclear in par t because of outcome data that are primarily subjective. The aim of this st udy was to evaluate and monitor these patients objectively using quantitati ve single-photon emission computed tomography (SPECT). Thirty-four patients were so observed clinically between 1987 and 1996 and were studied with an initial and at least one follow-up SPECT scintigram. initial radiographs a nd planar bone scans failed to demonstrate the pars lesion in 53 and 19% of the patients, respectively. The average SPECT ratio before brace treatment was 1.45. After treatment, this ratio significantly decreased to 1.27 (p = 0.03). A subset of patients remained symptomatic at follow-up. Their reduc tion in SPECT ratio averaged only 2.8% as compared with 13% for the remaind er of the patients (p = 0.01). Patients diagnosed and braced in the early, more active stage of the condition (with greater intensity on SPECT) had mo re predictable symptom relief. An initial SPECT ratio of >1.5 was associate d with complete symptom resolution after brace treatment. Patients treated with activity restriction only (>3 months) before bracing were more likely to have persistent symptoms and more modest improvement on SPECT (p = 0.01) . These data, which use SPECT scintigraphy, support prompt treatment with b race immobilization for acute spondylolysis in children and adolescents.