Department of Surgery at the Uniformed Services University of the Health Sciences and Walter Reed National Military Medical Center, Bethesda, Maryland.
Department of Orthopaedic Surgery, Captain James A. Lovell Federal Health Care Center, North Chicago, Illinois.
J Bone Joint Surg Am. 2023 Nov 15;105(22):1786-1792. doi: 10.2106/JBJS.22.01258. Epub 2023 Aug 15.
After combat-related lower extremity amputations, patients rapidly lose bone mineral density (BMD). As serial dual x-ray absorptiometry (DXA) scans are rarely performed in this setting, it is difficult to determine the timeline for bone loss and recovery or the role of interventions. However, a strong correlation has been demonstrated between DXA BMD and computed tomography (CT) signal attenuation. We sought to leverage multiple CT scans obtained after trauma to develop a predictive model for BMD after combat-related lower extremity amputations.
We reviewed amputations performed within the United States military between 2003 and 2016 in patients with multiple CT scans. We collected pertinent clinical information, including amputation level(s), complications, and time to weight-bearing. The primary outcome measure was the development of low BMD, estimated in Hounsfield units (HU) from CT scans with use of a previously validated method. One hundred and twenty-eight patients with 613 femoral neck CT scans were available for analysis. A least absolute shrinkage and selection operator (LASSO) multiple logistic regression analysis was applied to determine the effects of modifiable and non-modifiable variables on BMD. A random-effects model was applied to determine which factors were most predictive of low BMD and to quantify their effects.
Both amputated and non-amputated extremities demonstrated substantial BMD loss, which stabilized approximately 3 years after the injury. Loss of BMD followed a logarithmic pattern, stabilizing after 1,000 days. On average, amputated limbs lost approximately 100 HU of BMD after 1,000 days. Other factors identified by the mixed-effects model included nonambulatory status (-33.5 HU), age at injury (-3.4 HU per year), surgical complications delaying weight-bearing (-21.3 HU), transtibial amputation (20.9 HU), and active vitamin-D treatment (-19.7 HU).
Patients with combat-related lower extremity amputations experience an initially rapid decline in BMD in both intact and amputated limbs as a result of both modifiable and non-modifiable influences, including time to walking, amputation level, surgical complications, and age. The paradoxical association of vitamin-D supplementation with lower HU likely reflects this treatment being assigned to patients with low BMD. This model may assist with clinical decision-making prior to performing lower extremity amputation and also may assist providers with postoperative decision-making to optimize management for prophylaxis against osteoporosis.
Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.
在与战斗相关的下肢截肢后，患者的骨矿物质密度（BMD）迅速下降。由于在此情况下很少进行连续的双能 X 线吸收法（DXA）扫描，因此难以确定骨丢失和恢复的时间线，以及干预的作用。但是，已经证明 DXA BMD 与计算机断层扫描（CT）信号衰减之间存在很强的相关性。我们试图利用创伤后获得的多个 CT 扫描来建立与战斗相关的下肢截肢后 BMD 的预测模型。
我们回顾了 2003 年至 2016 年期间在美国军队中进行的截肢手术，这些患者均接受了多次 CT 扫描。我们收集了相关的临床信息，包括截肢部位、并发症和承重时间。主要观察指标是使用先前验证的方法从 CT 扫描中估算出的骨密度低（HU）。有 128 例患者有 613 个股骨颈 CT 扫描可供分析。应用最小绝对收缩和选择算子（LASSO）多变量逻辑回归分析来确定可改变和不可改变变量对 BMD 的影响。应用随机效应模型确定哪些因素对低 BMD 最具预测性，并量化其影响。
截肢和非截肢肢体均显示出大量的 BMD 丢失，这种丢失在受伤后约 3 年趋于稳定。BMD 的丢失呈对数模式，在 1000 天后稳定。平均而言，截肢肢体在 1000 天后丢失了约 100 HU 的 BMD。混合效应模型确定的其他因素包括非步行状态（-33.5 HU）、受伤时的年龄（每年减少 3.4 HU）、延迟承重的手术并发症（-21.3 HU）、经胫骨截肢（20.9 HU）和活性维生素 D 治疗（-19.7 HU）。
与战斗相关的下肢截肢患者，无论是完整的还是截肢的肢体，都会因多种可改变和不可改变的因素（包括行走时间、截肢水平、手术并发症和年龄）而导致 BMD 迅速下降。维生素 D 补充与较低的 HU 值之间的矛盾关联可能反映了这种治疗方法用于低 BMD 患者。该模型可能有助于在进行下肢截肢术之前进行临床决策，也可能有助于提供者做出术后决策，以优化骨质疏松症预防管理。
治疗性 3 级。有关证据水平的完整描述，请参阅作者说明。
