OBJECTIVES Low bone mineral status has been reported in patients first presented with adolescent idiopathic scoliosis (AIS). We aimed to study whether low-normal bone mineral density (BMD) is persistent among AIS girls during puberty and at peak bone mass, and whether if such persistence is associated with curve severity and differed from healthy controls. METHOD This prospective longitudinal study comprised 550 AIS girls and 194 healthy control subjects followed from 1997 till 2016. Low-normal BMD was defined as z-standardized bone mineral density (z-BMD) of bilateral femoral neck ≤ -1. Markov Chain 2-stages analysis was conducted to investigate the low-normal BMD transition rate. Linear mixed-effects model and Bland-Altman plot were used to investigate whether low-normal BMD is persistent among a subgroup of AIS patients that reached peak bone mass. RESULTS The average z-BMD were comparable between AIS cohort and controls at 11 years old (-0.532 vs -0.602), but at 19 years old z-BMD worsened among AIS subjects (-0.860) while controls z-BMD improved (-0.455). During growth period until skeletal maturity, persistence of low-normal BMD was high in both cohorts (>80%) and the AIS group with severe curve presented 100% persistence. Subgroup analysis revealed that z-BMD of AIS patients at skeletal maturity and peak bone mass were highly correlated (r2 = 0.905) and with good agreement. CONCLUSION AIS patients had poorer BMD that is associated with curve severity and more likely to persist beyond peripubertal period and at peak bone mass when compared to controls.

中文翻译：

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不同侧弯严重度的青少年特发性脊柱侧凸的持续低正常骨矿物质密度：从出现到超过骨骼成熟度和峰值骨量的纵向研究

目的 据报道，首次出现青少年特发性脊柱侧凸 (AIS) 的患者存在低骨矿物质状态。我们旨在研究 AIS 女孩在青春期和骨量峰值时是否持续存在正常低骨密度 (BMD)，以及这种持续性是否与弯曲严重程度相关并与健康对照组不同。方法 这项前瞻性纵向研究包括 550 名 AIS 女孩和 194 名健康对照受试者，从 1997 年到 2016 年。低正常 BMD 定义为双侧股骨颈的 z 标准化骨矿物质密度 (z-BMD) ≤ -1。进行马尔可夫链 2 阶段分析以研究低正常 BMD 转换率。使用线性混合效应模型和 Bland-Altman 图来研究低正常 BMD 在达到峰值骨量的 AIS 患者亚组中是否持续存在。结果 11 岁时，AIS 队列和对照组之间的平均 z-BMD 具有可比性（-0.532 vs -0.602），但在 19 岁时，AIS 受试者的 z-BMD 恶化（-0.860），而对照组的 z-BMD 改善（-0.455 ）。在直到骨骼成熟的生长期，两个队列中低正常 BMD 的持续性都很高（> 80％），并且具有严重曲线的 AIS 组呈现出 100％的持续性。亚组分析显示，AIS 患者骨骼成熟时的 z-BMD 与峰值骨量高度相关（r2 = 0.905），并且具有良好的一致性。