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Author ORCID Identifier

https://orcid.org/0009-0005-2486-7121

Date Available

5-1-2027

Year of Publication

2026

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Health Sciences

Department/School/Program

Rehabilitation Sciences

Faculty

Nicholas R. Heebner

Faculty

Brian W. Noehren

Faculty

Esther Dupont-Versteegden

Abstract

Bone stress injuries (BSIs) are a leading cause of medical attrition in U.S. Army Basic Combat Training (BCT), posing significant operational and financial burdens. There is a critical need to better understand how specific injury characteristics, anatomical burden, and physiological antecedents influence both immediate training success and long-term military career trajectories. This dissertation aimed to accomplish the following through four specific aims: 1) determine the association between MRI-defined injury characteristics and BCT graduation in femoral neck BSIs, 2) evaluate the impact of anatomical injury patterns and total injury count on attrition, 3) determine the long-term career and healthcare impacts of hip and pelvic BSIs, and 4) characterize longitudinal bone density adaptation in ROTC cadets.

In the first aim, a matched case-control study of trainees with femoral neck bone stress injuries (FNBSI) revealed that specific MRI characteristics are potent predictors of training outcomes. Trainees with high-grade injuries (Fredericson Grade 4) demonstrated significantly lower graduation rates compared to those with lower-grade injuries. Furthermore, bilateral involvement was independently associated with increased risk of discharge from BCT. These findings suggest that precise radiological grading beyond simple diagnostic presence is essential for risk stratification and clinical decision-making.

For the second aim, an analysis of 123,555 trainees identified a clear inverse dose-response relationship between the number of BSI-affected anatomical regions and BCT graduation success. Trainees with injuries to three or more anatomical sites demonstrated significantly higher attrition rates compared to those with isolated injuries. Additionally, injury location proved critical; trainees with femoral head or neck involvement faced significantly worse outcomes compared to those with injuries restricted to the pubic rami or sacrum, highlighting the prognostic importance of total bone stress burden.

In the third aim, the long-term career trajectory of trainees who sustained hip and pelvic BSIs was notably compromised compared to matched controls. Soldiers with a history of BSI exhibited lower graduation rates from subsequent Advanced Individual Training (AIT) and were significantly more likely to be separated from service within the first term of enlistment. Moreover, these individuals demonstrated persistently higher musculoskeletal healthcare utilization in the years following their initial injury, indicating that the consequences of BCT-sustained BSIs extend well beyond the initial training period.

In the fourth aim, longitudinal imaging of First-Year ROTC Cadets using high-resolution peripheral quantitative computed tomography (HR-pQCT) revealed distinct sex-specific bone phenotypes. Cadets with superior performance on the Army Combat Fitness Test (ACFT), particularly in power-based events, was positively associated with greater trabecular bone density and microarchitecture. Collectively, these findings provide military clinicians with data-driven guidelines to improve prognosis and optimize long-term force readiness

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2026.239

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