Post-Maturity Progression in Adolescent Idiopathic Scoliosis Curves of 40° to 50°

Background:Adolescent idiopathic scoliosis (AIS) curves of 50 degrees to 75 degrees are inclined to progress and are thus indicated for surgery. Nevertheless, the natural history of curves of 40 degrees to 50 degrees following skeletal maturity remains uncertain and presents a clinical dilemma. The aim of this study was to determine the prevalence, rate, and prognostic indicators of curve progression within this patient group.Methods:This was a retrospective study of 73 skeletally mature patients with AIS. Following yearly or more frequent follow-up, patients were stratified as having no progression (<5 degrees increase) or progression (>= 5 degrees increase). Those with progression were further differentiated as having standard progression (<2 degrees increase/year) or fast progression (>= 2 degrees increase/year). Radiographic parameters (coronal balance, sagittal balance, truncal shift, apical translation, T1 tilt, apical vertebral wedging) and height were determined on skeletal maturity. Parameters that were significantly associated with progression were subject to receiver operating characteristic (ROC) curve analysis.Results:The average period of post-maturity follow-up was 11.8 years. The prevalence of progression was 61.6%. Among those with progression, the curve increased by a mean of 1.47 degrees +/- 1.22 degrees per year, and among those with fast progression, by 3.0 degrees +/- 1.2 degrees per year. Thoracic apical vertebral wedging (concave/convex vertebral height x 100) was more apparent in those with progression than in those without progression (84.1 +/- 7.5 versus 88.6 +/- 3.1; p = 0.003). Increased coronal imbalance (C7 plumb line to central sacral vertebral line) differentiated those with fast progression from others (16.0 +/- 11.0 versus 8.7 +/- 7.7 mm; p = 0.007). An ROC curve of height-corrected coronal balance demonstrated an area under the curve (AUC) of 0.722, sensitivity of 75.0%, and specificity of 72.5% in identifying fast progression. An ROC curve of height-corrected coronal balance together with apical vertebral wedging to identify those with progression demonstrated an AUC of 0.746, with specificity of 93.7% and sensitivity of 64.5%.Conclusions:While the majority of curves progressed, the average rate of progression was slow, and thus, yearly observation was a reasonable management approach. Upon validation in larger cohorts, apical wedging and coronal imbalance may identity patients suited for closer monitoring and early spinal fusion.

Automated summary

The aim of this study was to determine the progression of curves of 40 degrees to 50 degrees following skeletal maturity. The study found that although most of the patients showed progression, the rate of progression was slow, suggesting that yearly observation was a reasonable management approach. Apical wedging and coronal imbalance could potentially serve as indicators for closer monitoring and early spinal fusion in these patients.