Spontaneous lumbar curve correction after selective thoracic fusion in surgery for adolescent idiopathic scoliosis (AIS) is well described. However, only a few articles have described the course of the uninstrumented upper thoracic (UT) curve after fusion, and the majority involve a hybrid construct. In this study, the authors sought to determine the outcomes and associated factors of uninstrumented UT curves in patients with AIS.

The authors retrospectively reviewed a prospectively collected multicenter AIS registry for all consecutive patients with Lenke type 1–4 curves with a 2-year minimum follow-up. UT curves were considered uninstrumented if the upper instrumented vertebra (UIV) did not extend above 1 level from the lower end vertebra of the UT curve. The authors defined progression as > 5°, and divided patients into two cohorts: those with improvement in the UT curve (IMP) and those without improvement in the UT curve (NO IMP). Radiographic, demographic, and Scoliosis Research Society (SRS)–22 survey outcome measures were compared using univariate analysis, and significant factors were compared using a multivariate regression model.

The study included 450 patients (370 females and 80 males). The UT curve self-corrected in 86% of patients (n = 385), there was no change in 14% (n = 65), and no patients worsened. Preoperatively, patients were similar with respect to Lenke classification (p = 0.44), age (p = 0.31), sex (p = 0.85), and Risser score (p = 0.14). The UT curves in the IMP group self-corrected from 24.7° ± 6.5° to 12.6° ± 5.9°, whereas in the NO IMP group UT curves remained the same, from 20.3° ± 5.8° to 18.5° ± 5.7°. In a multivariate analysis, preoperative main thoracic (MT) curve size (p = 0.004) and MT curve correction (p = 0.001) remained significant predictors of UT curve improvement. Greater correction of the MT curve and larger initial MT curve size were associated with greater likelihood of UT curve improvement.

Spontaneous UT curve correction occurred in the majority (86%) of unfused UT curves after MT curve correction in Lenke 1–4 curve types. The magnitude of preoperative MT curve size and postoperative MT curve correction were independent predictors of spontaneous UT curve correction.

青少年特发性脊柱侧弯 (AIS) 手术中选择性胸椎融合术后自发性腰椎曲线矫正已得到很好的描述。然而，只有少数文章描述了融合后未经器械测量的上胸椎 (UT) 曲线的过程，并且大多数涉及混合结构。在这项研究中，作者试图确定 AIS 患者未检测 UT 曲线的结果和相关因素。

作者回顾性地审查了一项前瞻性收集的多中心 AIS 登记表，该登记表适用于所有具有 Lenke 1-4 型曲线且最少随访 2 年的连续患者。如果上器械椎骨 (UIV) 没有从 UT 曲线的下端椎骨延伸到 1 级以上，则认为 UT 曲线没有器械。作者将进展定义为 > 5°，并将患者分为两组：UT 曲线改善 (IMP) 和 UT 曲线未改善 (NO IMP)。使用单变量分析比较放射学、人口统计学和脊柱侧弯研究协会 (SRS)–22 调查结果测量，并使用多变量回归模型比较重要因素。

该研究包括 450 名患者（370 名女性和 80 名男性）。86% 的患者 (n = 385) 的 UT 曲线自我矫正，14% (n = 65) 没有变化，并且没有患者恶化。术前，患者在 Lenke 分类（p = 0.44）、年龄（p = 0.31）、性别（p = 0.85）和 Risser 评分（p = 0.14）方面相似。IMP组的UT曲线自校正从24.7°±6.5°到12.6°±5.9°，而NO IMP组的UT曲线保持不变，从20.3°±5.8°到18.5°±5.7°。在多变量分析中，术前主胸椎 (MT) 曲线大小 (p = 0.004) 和 MT 曲线矫正 (p = 0.001) 仍然是 UT 曲线改善的重要预测因素。MT 曲线的更大修正和更大的初始 MT 曲线尺寸与 UT 曲线改善的更大可能性相关。

在 Lenke 1-4 曲线类型的 MT 曲线校正后，大多数 (86%) 未融合的 UT 曲线发生了自发的 UT 曲线校正。术前 MT 曲线大小和术后 MT 曲线矫正的大小是自发性 UT 曲线矫正的独立预测因素。