Background: Spondylolysis defects detected by nuclear scintigraphy but not by plain radiographs represent early lesions. Functional outcome and eventual bony union of these defects are unknown.
Hypothesis: Defects with greater degree of healing shortly after treatment will proceed to full bony union and better long-term functional outcome.
Study design: Longitudinal cohort study.
Methods: Forty young athletes with early detected spondylolysis (radiograph negative, nuclear scintigraphy positive) were divided into 3 stages of healing by computed tomography scan. Functional outcome was assessed 7 to 11 years later using the low back outcome score and other factors. Degree of bony healing was assessed in volunteers.
Results: Thirty-two of 40 subjects (80%) completed the survey. Twenty-nine of 32 (91%) had good or excellent low back outcome scores. None required spinal fusion, but 1 required partial diskectomy. Functional outcome did not differ based on initial computed tomography results. Radiographic follow-up was obtained in 11 volunteers. None of the 7 bilateral defects healed, and 3 of these progressed to grade 1 spondylolisthesis. All 4 unilateral defects healed fully with bone.
Conclusions: Most young athletes conservatively treated for early spondylolysis maintain good functional outcome up to 11 years later. Unilateral defects can undergo full bony healing but may take longer than 12 weeks. Bilateral defects may undergo further degeneration and slip with time.