Large L5–S1 Lordosis is an Independent Risk Factor for recurrENCE AFTER BOne Union of Pediatric Lumbar Spondylolysis at L5

Study Design: Retrospective case-control study. Objective. To determine risk factors for recurrence of pediatric lumbar spondylolysis at L5 after return to sport in patients who achieved bone union with conservative treatment. Summary of Background Data. Pediatric lumbar spondylolysis is a stress fracture commonly observed in adolescent athletes, particularly at the L5 vertebra. Because some patients experience a recurrence of spondylolysis after bone fusion with conservative treatment, identifying risk factors for recurrence may help athletes continue sports activities, maintain performance levels, and preserve mental health. Methods. Of the 375 pediatric patients (<18 years of age) who received conservative treatment for lumbar spondylolysis at L5 between 2015 and 2021, 296 patients who achieved bone fusion and returned to their original sports activities were analyzed. Recurrence rate, sports, pathological stage of spondylolysis at initial examination, presence of spina bifida occulta (SBO), duration of conservative treatment for initial spondylolysis, and radiological parameters including lumber lordosis, L5–S1 lordosis, and sacral slope were examined. Recurrence and non-recurrence groups were compared using univariate and multivariate analyses to investigate risk factors for recurrence. A receiver operating characteristic (ROC) curve was drawn to determine cut-off values of the parameters to predict spondylolysis recurrence. Results. Recurrence was observed in 52 out of 296 patients (17.6%). Multivariate logistic regression analysis revealed that a large L5–S1 lordosis was a significant independent risk factor for recurrence. ROC analysis demonstrated a cut-off value of 24.5° for L5–S1 lordosis. Age, sex, SBO, and duration of conservative treatment for initial spondylolysis were not significant predictors of recurrence. Conclusion. We identified large L5–S1 lordosis as an independent risk factor for recurrence of pediatric lumbar spondylolysis at L5 following conservative treatment. Intensive athletic rehabilitation to prevent recurrence and follow-up measures to monitor and detect recurrence are recommended for patients with large L5–S1 lordosis.