Background 

Femoral neck stress fractures are a common condition affecting military service members, most noticeably during basic combat training. Previous studies have investigated the risk factors for femoral neck stress fracture development in basic trainees and outcomes associated with treatment; however, few studies have focused on operatively treated femoral neck stress fracture in the military trainee. Doing so would be important not only for the military, but also providers caring for athletes, such as distance runners, who have a heightened risk for femoral neck stress fracture development.

Questions/purposes 

(1) What proportion of US Army trainees completing basic combat training at Fort Jackson, SC, USA, who undergo surgery for femoral neck stress fracture during basic training subsequently leave military service because of the injury? (2) What factors are related to the patient or the fracture are associated with a higher likelihood of military separation? (3) What factors on the initial MRI are associated with progression of the stress fracture extent?

Methods 

A retrospective study of a longitudinally maintained database of stress injuries involving basic combat trainees from a single military post was reviewed over a 3-year period. Inclusion criteria included basic trainees undergoing surgery for a femoral neck stress fracture between January 2018 and June 2020 with a minimum of 1-year follow-up. Surgery was indicated for service members with complete and tension-sided femoral neck stress fractures and those with high risk compression-sided stress fractures, generally representing fractures involving more than 50% of the femoral neck width. Over the study period, 57 service members (51% [29 of 57] women with a mean age of 24 years) underwent surgery for a femoral neck stress fracture, and all 57 had a minimum of 1-year follow-up. Identified service members underwent independent data collection including injury and radiographic parameters based on chart and imaging review. Documented fracture line progression on repeat imaging was present in 39% of service members, with a mean fracture line progression of 55% of the femoral neck width. Service members were subdivided based upon the ability to return to military service at 1 year. Univariate analysis was performed using patient and injury variables to identify factors associated with the ability to return to military service.

Results 

Overall, 58% (33 of 57) of service members who had a femoral neck stress fracture treated surgically underwent military separation. A higher proportion of service members who demonstrated fracture line progression leading to surgical treatment remained in the military (58% [14 of 24] versus 30% [10 of 33]; odds ratio 0.3 [95% confidence interval (CI) 0.1 to 0.9]; p = 0.03). With the numbers available, we found no other patient- or fracture-related variables associated with military separation, although we suspect we may have been underpowered on some of these comparisons, in particular gender (61% [20 of 33] of individuals separated after surgery for this injury were women compared with 38% [9 of 24] who were retained; OR 2.6 [95% CI 0.9 to 7.56]; p = 0.09). The extent of osseous edema on T1-weighted imaging in association with a hip effusion demonstrated a significant positive correlation with final fracture percentage (r = 0.62; p = 0.003).

Conclusion 

Military service members with a femoral neck stress fracture initially managed nonoperatively but with progression of the fracture line requiring surgical intervention were more likely to return to military duties and complete basic combat training, suggesting that early diagnosis of femoral neck stress fractures may be associated with better functional recovery after surgical treatment. Additionally, the extent of the osseous edema on initial MRI T1-weighted imaging sequences may help predict the final extent of femoral neck stress fractures on repeat imaging. Further investigations should incorporate patient-reported outcomes and further explore factors associated with fracture progression and the inability to return to active duty or sport.

Level of Evidence 

Level III, therapeutic study.

中文翻译：

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手术治疗的股骨颈应力性骨折可能会导致基本战斗训练期间的军事分离

背景 

股骨颈应力性骨折是影响军人的常见病症，尤其是在基础战斗训练期间。先前的研究调查了基础学员发生股骨颈应力性骨折的危险因素以及与治疗相关的结果；然而，很少有研究关注军事学员股骨颈应力性骨折的手术治疗。这样做不仅对军队很重要，而且对照顾长跑运动员等运动员的医疗服务提供者也很重要，因为他们发生股骨颈应力性骨折的风险较高。

问题/目的 

(1) 在美国南卡罗来纳州杰克逊堡完成基础战斗训练的美国陆军学员中，在基础训练期间接受股骨颈应力性骨折手术的美国陆军学员中，有多少比例因受伤而退伍？(2) 哪些因素与患者或骨折相关，与军事分离的可能性较高有关？(3) 初始 MRI 上的哪些因素与应力性骨折程度的进展相关？

方法 

对一个纵向维护的压力损伤数据库进行了回顾性研究，该数据库涉及来自单个军事岗位的基本战斗学员，历时三年。纳入标准包括 2018 年 1 月至 2020 年 6 月期间接受股骨颈应力性骨折手术且至少随访 1 年的基础学员。对于完全性和张力侧股骨颈应力性骨折以及高风险压缩侧应力性骨折（通常代表股骨颈宽度超过 50% 的骨折）的军人来说，需要进行手术。在研究期间，57 名军人（51% [57 人中的 29 人] 为女性，平均年龄为 24 岁）接受了股骨颈应力性骨折手术，所有 57 人都接受了至少 1 年的随访。确定的服役人员接受了独立的数据收集，包括基于图表和成像审查的损伤和放射学参数。重复成像记录显示，39% 的军人出现骨折线进展，平均骨折线进展为股骨颈宽度的 55%。服役人员根据一年后重返兵役的能力进行细分。使用患者和受伤变量进行单变量分析，以确定与重返兵役能力相关的因素。

结果 

总体而言，58%（57 名中的 33 名）接受手术治疗股骨颈应力性骨折的军人接受了军事分离。表现出骨折线进展导致手术治疗的军人比例较高（58% [24 人中的 14 人] vs 30% [33 人中的 10 人]；优势比 0.3 [95% 置信区间 (CI) 0.1 至 0.9） ]；p = 0.03）。根据可用的数据，我们没有发现与军事分离相关的其他与患者或骨折相关的变量，尽管我们怀疑我们在其中一些比较中可能动力不足，特别是性别（61％[33人中的20人]在军事分离后分离）接受该损伤手术的患者为女性，而保留手术的患者为 38%（24 人中的 9 人）；OR 2.6 [95% CI 0.9 至 7.56]；p = 0.09）。T1 加权成像上与髋部积液相关的骨水肿程度与最终骨折百分比呈显着正相关（r = 0.62；p = 0.003）。

结论 

患有股骨颈应力性骨折的军人最初接受非手术治疗，但随着骨折线的进展需要手术干预，他们更有可能重返军队并完成基本的战斗训练，这表明股骨颈应力性骨折的早期诊断可能与更好的治疗效果相关。手术治疗后功能恢复。此外，初始 MRI T1 加权成像序列上的骨水肿程度可能有助于预测重复成像时股骨颈应力性骨折的最终程度。进一步的调查应纳入患者报告的结果，并进一步探讨与骨折进展和无法重返现役或运动相关的因素。

证据水平 

III级，治疗研究。