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Benchmarking surgical indications for adolescent idiopathic scoliosis across time, region, and patient population: a study of 4229 cases



There is no identified consensus for the curve magnitude at which an adolescent idiopathic scoliosis (AIS) patient is indicated for posterior spinal fusion (PSF). We aimed to identify a benchmark for curve magnitude at which fusion is indicated; we also aimed to evaluate which patients were being fused under 50°.


A prospective multicenter AIS database was queried to identify patients who underwent PSF for AIS. Clinical outcome and demographic information was collected along with anatomic area of the primary curve. Benchmarking was assessed by median and IQR. Patients were stratified by fusion prior to 50° or at 50° or more, and statistical analysis was performed to assess risk factors for fusion < 50°.


4229 patients were included in the analysis. The median indication for PSF in the thoracic curve cohort was 55°, and in the lumbar curve cohort was 51°. Site-specific evaluation showed that two sites were more likely to fuse < 50° compared to all other sites (p < 0.05). Over time, the percentage of patients being fused < 50° has declined (p < 0.05). On univariate and multivariate analysis, lumbar curve location, increasing Risser score and female sex were all risk factors for fusion < 50° (p < 0.05). Low SRS-24 scores did not correlate to fusion below 50°.


There exist location-specific indications for posterior spinal fusion that vary throughout the country. Additionally, increasing maturity, female sex, and lumbar curve location are independent risk factors for fusion under 50°.

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Availability of data and materials

This study was performed utilizing the Harms Study Group database.


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This study was performed utilizing the Harms Study Group database, and the main institution receives funding from the Setting Scoliosis Straight Foundation in support of Harms Study Group research.

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Correspondence to John M. Flynn.

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The authors have no conflicts of interest to declare that are relevant to the content of this article.

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The institutional review boards (IRBs) of each participating site approved the participation in the study prior to collection of patient data.

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Informed consent was obtained from all patients (or their legal guardians) at each participating institution at the onset of the study.

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Patients (or their legal guardians) were individually consented at each participating institution for inclusion of their data in published studies; all data are deidentified by the Harms Study Group database. There are no identifiable data or imaging included in this study.

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Heyer, J.H., Baldwin, K.D., Shah, A.S. et al. Benchmarking surgical indications for adolescent idiopathic scoliosis across time, region, and patient population: a study of 4229 cases. Spine Deform 10, 833–840 (2022).

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  • Posterior spinal fusion
  • Adolescent idiopathic scoliosis
  • Surgical indications