Risk of Scoliosis Progression in Nonoperatively Treated Adolescent Idiopathic Scoliosis Based on Skeletal Maturity

Background: Hand radiographs for skeletal maturity staging are now frequently used to evaluate remaining growth potential for patients with adolescent idiopathic scoliosis (AIS). Our objective was to create a model predicting a patient's risk of curve progression based on modern treatment standards.

Methods: We retrospectively reviewed all AIS patients presenting with a major curve <50 degrees, available hand radiographs, and complete follow up through skeletal maturity at our institution over a 3-year period. Patients with growth remaining underwent rigid bracing of curves >25 degrees, whereas patients between 10 and 25 degrees were observed. Treatment success was defined as reaching skeletal maturity with a major curve <50 degrees. Four risk categories were identified based on likelihood of curve progression.

Results: Of 609 AIS patients (75.4% female) presenting with curves over 10 degrees and reaching skeletal maturity at most recent follow up, 503 (82.6%) had major thoracic curves. 16.3% (82/503) of thoracic curves progressed into surgical treatment range. The highest risk group (Sanders 1 to 6 and curve 40 to 49 degrees, Sanders 1 to 2 and curve 30 to 39) demonstrate a 30% success rate with nonoperative treatment. This constitutes an 111.1 times (95% confidence interval: 47.6 to 250.0, P<0.001) higher risk of progression to surgical range than patients in the lowest risk categories (Sanders 1 to 8 and curve 10 to 19 degrees, Sanders 3 to 8 and curve 20 to 29 degrees, Sanders 5 to 8 and curve 30 to 39 degrees).

Conclusions: Skeletal maturity and curve magnitude have strong predictive value for future curve progression. The results presented here represent a valuable resource for orthopaedic providers regarding a patient's risk of progression and ultimate surgical risk.

Level of evidence: Level III-retrospective cohort study.