ABSTRACT: Nguyen, Brown, Formby, Edgeworth, White-Phillip, and Harris TITLE: Orthopedic Healthcare Disparity Effects on US Military Readiness and Retention INTRODUCTION: Access to trauma centers and orthopedic surgery clinics plays a crucial role in ensuring timely and effective medical care, especially for active-duty service members (ADSM) who face unique challenges related to readiness and longevity in service. Noncombat related musculoskeletal injuries (MSKI) are the leading cause of disability in the US military, affecting more than 800,000 service members annually and resulting in millions of limited duty days (3). These injuries cost the US Department of Defense (DoD) upwards of 3.7 billion dollars in direct and indirect costs (3). Some MSK injuries require specialty care to maximize return to duty. However, a recent Investigator General’s report revealed that shortages of specialty care may be a common challenge faced by ADSM and their families. About half of all US military bases are in federally designated healthcare deserts (8). Healthcare deserts, (HCD) are areas across the U.S. where a lack adequate access to six key healthcare services exist: (1) pharmacies, (2) primary care providers, (3) hospitals, (4) hospital beds, (5) trauma centers, and (6) low-cost health centers (6). Annually, thousands of patients are seen in military orthopaedic clinics, but there are currently only nine orthopedic surgery training programs between the tri-service medical branches, and only one of these programs is located in a military treatment facility (MTF) that qualifies as a level one trauma center (10). In addition to scarce orthopedic resources, stress fractures plague the military community. Presence of a stress fracture during basic training is a powerful predictor of military discharge and remains a source of ADSM disability (12). These injuries are difficult to diagnose and treat and furthermore, will worsen over time without appropriate treatment. It is critical to identify these injuries soon after occurrence. Diagnostic delay increases the risk of nonunion, malunion, or progression to a complete or displaced fracture requiring surgery. Because stress fractures identified in a timely fashion can be successfully treated nonoperatively, we employed the diagnosis, progression, treatment, and rehabilitation of these injuries to capture the effects of healthcare deserts on ADSM readiness and retention. METHODS: Our design involves an observational, retrospective study using de-identified data sourced from the Medical Assessment and Readiness System (MARS) at Womack Army Medical Center to identify ADSMs with fractures across all body regions (except for the head) from 2011 to 2021. In addition, we utilized the DoD catalog mapping Military Installations, Ranges, and Training Areas to identify which installations were located within a previously defined healthcare (trauma center) desert (6). We compared ADSM data between installations with and without facilities fully equipped with trauma centers and access to orthopedic surgery care. We conducted survival analysis to assess the effect of social and community factors associated with HCDs on the risk of fitness outcomes (9). We followed specific readiness variables outcomes (including but not limited to): time on profile (mean days on profile), injuries (mean number of orthopedic procedures and diagnosis), ACFT/APFT (mean physical fitness scores). Factors associated with HCDs included proximity to the MTF, clinic and patient income level, and social deprivation index (SDI) as a composite measure of area-level deprivation.(9) Collectively, these HCD related metrics were used to determine changes in the risk of poor fitness outcomes among ADSMs recovering from a fracture. Other important measurements captured in this study include mean days from initial referral to orthopedic surgery appointment, mean days from initial injury to surgery. We also included analysis of retention measures such as mean days in active service and percent of ADSM whose injuries progress to medical separation. Extracted data were further categorized by sex, race, age, rank, and branch of service. RESULTS: Our preliminary investigation focused on analyzing the relationship between post-fracture rehabilitation and tangible physical readiness measurements as captured by the APFT. Of the 1,289,953 ADSMs that served in the Army between 2011 and 2021, there were 138,649 incident fractures (10.8%). Among those with a fracture, three-quarters received physical therapy within six months of fracture diagnosis. There were 12,828 post-fracture APFT failures (9.3%) and those without a failure had a significantly shorter wait time to first physical therapy (PT) session (APFT Failure: 9.8 months to PT; 95%CI: 7.8-11.7; APFT Pass: 4.8 months to PT; 95%CI: 4.0-5.6; P<0.001). Post-fracture APFT failure risk increased by about 15% when time to first PT session exceeded 3 months (4-6 months: AHR = 1.18; 95%CI: 1.09-1.27; P<0.001). Increased clinic SDI was associated with a slight increase in risk (Clinic SDI 26-50: AHR = 1.04; 95%CI: 1.00-1.09; P=0.047). However, we found that a high clinic SDI was unexpectedly correlated with a decrease in APFT failure (Clinic SDI 76-100: AHR = 0.87; 95%CI: 0.77-0.98; P=0.024), while increasing patient SDI was not strongly associated with any increasing risk of APFT failure. Risk increase varied by body region of fracture with the highest increase of 30% after wrist or hand fracture (AHR = 1.30; 95%CI: 1.22-1.38; P<0.001), which we noted because orthopaedic hand injuries are a significant detriment to readiness in both deployed and garrison operations. Risk also increased with female sex, younger age and lower rank, non-white race, and increased BMI. CONCLUSION: The risk increase of APFT failure after fracture was highest among those with longer physical therapy wait times. Interestingly, high SDI may be protective against post-fracture APFT failure. Within this population, we are currently continuing our investigation including the scope and timeline of fracture progression to compare the course of diagnosis from stress fracture through progressive fracture type and severity, as well as the timeline of orthopedic surgery referrals and surgical interventions within the population of ADSM who passed and failed APFT to capture these metrics in our analysis. Furthermore, understanding risk differences across body regions and increased risk of APFT failure after extremity fractures may provide an opportunity to suggest data-driven allocation of physical therapy and specialty surgical training resources. These additional results could provide data to inform targeted policy interventions and strategic healthcare planning wherein healthcare resources are allocated to maximize readiness efforts.