Attempted Development of a Clinical Decision-making Model to Assist in Femoral Neck Stress Fracture Screening in Military Trainees

Abstract

Background: Femoral neck stress fractures (FNSF) are serious injuries prevalent throughout the military, particularly within the initial entry training (IET) population. Delay in diagnosis and management can lead to complications secondary to fracture progression and displacement. Effective screening and identification of FNSF can reduce patient risk, mitigate costs associated with treatment, and prevent the potential medical discharge of IET personnel. There is currently no validated testing to assist in decisions for ordering advanced imaging to rule out FNSF. Military healthcare providers, therefore, must rely on advanced imaging of patients with hip region complaints to rule out suspected FNSF resulting in potential MRI over utilization. The purpose of this project was to determine if a clinical decision model can be developed from clinical findings to assist clinicians in deciding when magnetic resonance imaging (MRI) is warranted for FNSF screening in IET personnel with hip or groin pain. Methods: This was a prospective observational cross-sectional cohort process improvement project. We screened all IET Soldiers presenting to a medical clinic with hip or groin pain and evaluated 18 clinical variables. The reference standard was a FNSF diagnosed using fast-sequence MRI. Statistical analyses included correlation, receiver operating characteristic (ROC) curve assessments, and regression.Results: Final statistical analysis included 184 IET Soldiers, of which 49 had a FNSF. Frequency analysis observed the highest occurrence of FNSF in non-Hispanic white females. Ten subjective and physical examination variables had a weak correlation to positive MRI findings for FNSF. Regression analysis revealed six variables with positive MRI outcome predictive abilities; however, small to medium effect sizes, low ability to account for MRI outcome variance, and poor estimated sensitivity on ROC curve analysis limit this regression model’s clinical usefulness utilizing the identified variables. Conclusions: The regression models evaluating the clinical variables within this project failed to demonstrate adequate predictability and clinical usefulness when screening for the high-risk injury FNSF in an IET population. Clinicians should maintain a low threshold for ordering an MRI to screen for FNSF in this population. Clinicians also cannot rely on subject-reported pain locations or objective testing as definitive assessment signs to distinguish between IET Soldiers with and without a FNSF.Trial Registration: This study was deemed as a process improvement project by the Brooke Army Medical Center Institutional Review Board on 7 August 2017. A trial registration was not needed.