Background: 

Adolescent idiopathic scoliosis (AIS) curves of 50° to 75° are inclined to progress and are thus indicated for surgery. Nevertheless, the natural history of curves of 40° to 50° 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° increase) or progression (≥5° increase). Those with progression were further differentiated as having standard progression (<2° increase/year) or fast progression (≥2° 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° ± 1.22° per year, and among those with fast progression, by 3.0° ± 1.2° per year. Thoracic apical vertebral wedging (concave/convex vertebral height × 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.

Level of Evidence: 

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

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40° 至 50° 青少年特发性脊柱侧凸曲线的成熟后进展

背景： 

50° 至 75° 的青少年特发性脊柱侧凸 (AIS) 曲线倾向于进展，因此适合手术治疗。然而，骨骼成熟后 40° 至 50° 曲线的自然历史仍然不确定，并呈现出临床困境。本研究的目的是确定该患者组中曲线进展的患病率、发生率和预后指标。

方法： 

这是一项针对 73 名骨骼成熟的 AIS 患者的回顾性研究。每年或更频繁的随访后，患者被分层为无进展（<5°增加）或进展（≥5°增加）。那些进展的患者进一步分为标准进展（每年增加<2°）或快速进展（每年增加≥2°）。根据骨骼成熟度确定射线照相参数（冠状平衡、矢状平衡、躯干移位、顶端平移、T1 倾斜、顶端椎体楔入）和高度。与进展显着相关的参数接受受试者工作特征（ROC）曲线分析。

结果： 

平均随访期为11.8年。进展率为 61.6%。在进展的患者中，曲线每年平均增加 1.47° ± 1.22°，而在快速进展的患者中，曲线每年平均增加 3.0° ± 1.2°。胸椎尖椎楔入（凹/凸椎体高度 × 100）在进展患者中比未进展患者更明显（84.1 ± 7.5 对比 88.6 ± 3.1；p = 0.003）。冠状不平衡的增加（C7 铅垂线到中央骶椎线）将快速进展的患者与其他患者区分开来（16.0 ± 11.0 与 8.7 ± 7.7 mm；p = 0.007）。高度校正冠状平衡的 ROC 曲线显示，在识别快速进展方面，曲线下面积 (AUC) 为 0.722，敏感性为 75.0%，特异性为 72.5%。

结论： 

虽然大多数曲线都在进展，但平均进展速度很慢，因此，每年观察是一种合理的管理方法。经过更大队列的验证，心尖楔入和冠状不平衡可能会识别出适合密切监测和早期脊柱融合的患者。

证据级别： 

预后III 级。有关证据级别的完整描述，请参阅作者须知。