The most common reason for ambulatory visits within the military has consistently been the “musculoskeletal system,” and the rate per person year has steadily increased over the 2012 to 2017 time period.  Additionally, injury and poisonings are the 5th most common cause of ambulatory healthcare visits in the US Armed Forces, which also increased over the time period between 2012 and 2017. While the absolute number of visits is impacted by the annual end strength of the Armed Forces, the rate of ambulatory visits has not changed considerably between 2012 and 2017 despite fluctuations in total number of personnel. Overall, more than half the active component of the Armed Forces personnel had an ambulatory visit for an injury event each year resulting in an annual per person rate of 0.6-0.7, or roughly two in three personnel.

The direct care system (DCS) includes military treatment facilities (MTF) comprised of medical centers, hospitals, and clinics found at military bases and posts in the US and around the world dedicated to providing healthcare to DoD-eligible beneficiaries and staffed and run by DoD personnel. In addition, the military health system (MHS) provides purchased care contracted outside of an MTF that provides or supplements care to beneficiaries that is either unavailable in the DCS or falls outside the MTF market area.

For personnel treated at a MTF, disposition (ie, full, light or limited duty) of patients are tracked closely. In 2017, the illness-and injury-related diagnostic categories with the highest proportions of “limited-duty” dispositions were injuries and poisonings (17.5%) and musculoskeletal disorders (13%).1 However, treatment visits in purchased care facilities are not always identified. (Reference Table 5F.1.3.1 PDF CSV and Table 5F.1.3.3 PDF CSV)

bmus_e4_g5f.3.1.png

Unlike hospitalizations for injury/poisoning events, where females are slightly less likely to be hospitalized, they are slightly more likely to have an ambulatory visit. (Reference Table 5F.1.3.2 PDF CSV)

Cause of Ambulatory Visits

The diagnostic cause of ambulatory visits for injury/poisoning events is also provided in the MSMR Annual Summary Edition. While the proportion of visits varies somewhat by year and by sex, injury causes are consistent overall with the top two injuries being ankle sprains and sprains of the cruciate ligament of the knee. Between 8% and 10% of all ambulatory injuries are a sprain of the ankle, with foot injuries sometimes included in this diagnosis category depending on coding. Sprains of the cruciate ligament (knee) is the second most common, accounting for 3% to 4% of injuries. Sprains and strains of the shoulder and upper arm are more common among males, while females are more often diagnosed with sprain of the hip. (Reference Table 5F.1.3.4 PDF CSV)

Chronic and Overuse Injuries

Routine, repetitive physical training and job requirements place service members at risk for common overuse conditions throughout the body. Prolonged overhead activities combined with routine physical training involving push-ups and pull-ups place this population at risk of developing common chronic conditions of the upper extremity. Some of the most common conditions include shoulder impingement, rotator cuff tendinopathy, medial and lateral epicondylitis, and degenerative wrist conditions like scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC). Patellofemoral syndrome, patellar tendinitis, and iliotibial band syndrome are among the common overuse injuries affecting the knee in activity duty military populations. Ankle sprains leading to chronic ankle instability are also a common cause of disability in this cohort and occur at a rate 5-6 times higher than in the general population.2 Finally, chronic back and neck issues are a significant cause of morbidity and can ultimately result in the inability of the patient to perform the duties required of them to remain on Active Duty.

Stress fractures have long been a subject of interest in the military population given the treatment cost and significant time lost to injury this condition has. A recent epidemiological study found 31,758 lower extremity stress fractures occurred over a three-year time period, with 40% occurring in the tibia/fibula, 16% in the metatarsals, 9% in the femoral neck, 6% in the femoral shaft, and 30% in other unspecified bones.3 Females had a significantly increased risk of suffering from a stress fracture in any bone compared to their male counterparts; nearly 3-fold in this study. This gender difference has been repeatedly demonstrated and is attributed to anatomic, physiologic, and endocrinologic differences between males and females.4^,5^,6 Given the significant burden this condition has on troop readiness, identifying those at risk for stress fractures and improving prevention strategies should be a primary research focus going forward.

Acute Injuries

Acute injuries in the Active Duty population occur most commonly as a result of training accidents or sporting injuries. Causes of injury hospitalizations are coded according to the coding scheme outlined in the North Atlantic Treaty Organization (NATO) Standardization Agreement (STANAG) No. 2050, ed. 5.7

Falls and land transport consistently rank as the top unintentional causes for injury hospitalizations. Among all medical encounters for injuries and poisoning events (both hospitalization and ambulatory), musculoskeletal injuries to the knee, arm and shoulder, and foot and ankle all consistently rank in the top 10 out of 142 disease conditions.  This is true both in total number of encounters and individuals affected, comprising at least two-thirds of medical encounters and more than one-half of individuals affected attributable to injuries and poisoning. (Reference Table 5F.1.4.1 PDF CSV and Table 5F.1.4.2 PDF CSV)

bmus_e4_g5f.4.1.png

Among the most common acute injuries managed in the military population are fractures, ligamentous or meniscal knee injuries, and shoulder dislocations. Fractures can occur anywhere in the body but most often are seen in the hand and wrist (metacarpals, scaphoid, distal radius), ankle, and clavicle in the active duty population, and occur at a higher incidence than their civilian counterparts.8^,9^,10 These fractures often require operative fixation resulting in significant lost duty time and an increased likelihood that the patient is unable to return to full duty.   

Multiple studies have shown an almost 10-fold higher incidence of anterior cruciate ligament and meniscal injuries in active duty service members compared to the general population.11^,12^,13 In contrast to injury patterns seen in civilians, men were at increased risks of sustaining these injuries compared to females; this may be attributable to differences in occupational tasks and activities between men and women in the military.

Shoulder dislocations and resultant shoulder instability are ubiquitous in the Active Duty population; a 7 to 21 times higher incidence of shoulder dislocation injury has been reported compared to the general population.14^,15 These injuries often require surgical repair in this population with approximately 9% of those who require surgery being discharged for disability due to their injury.16

Identifying those at risk of sustaining these debilitating injuries and implementing preventive strategies should be of utmost importance in attempting to curb the resultant costly disability to our military members.

• 1. Armed Forces Health Surveillance Branch. Ambulatory visits, active component, US Armed Forces, 2017. U.S. Armed Forces. MSMR Annual Summary Edition 2018:25(5);17-23.
• 2. Waterman BR, Owens BD, Davey S, et al. The epidemiology of ankle sprains in the United States. J Bone Joint Surg Am 2010; 92(13):2279-2284. doi: 10.2106/JBJS.I.01537.
• 3. Waterman BR, Gun B, Bader JO, et al. Epidemiology of lower extremity stress fractures in the United States military. Mil Med 2016; 181(10):1308-1313.
• 4. Jacobs JM, Cameron KL, Bojescul JA. Lower extremity stress fractures in the military. Clin Sports Med 2014; 33(4):591-613. doi: 10.1016/j.csm.2014.06.002.
• 5. Mattila VM, Niva M, Kiruru M, Pihlajamaki H. Risk factors for bone stress injuries: a follow-up study of 102,515 person-years. Med Sci Sports Exerc 2007; 39(7):1061-1066.
• 6. Wentz L, Liu PY, Haymes E, Ilich JZ. Females have a greater incidence of stress fractures than males in both military and athletic populations: a systematic review. Mil Med 2011; 176(4):420-430.
• 7. Ministry of Defence. Annual medical discharges in the UK regular armed forces: 1 April 2013 to 31 March 2018. July 12, 2018. https://www.gov.uk/government/collections/medical-discharges-among-uk-service-personnel-statistics-index. Accessed November 29, 2018.
• 8. Dichiera R, Dunn J, Bader J, Bulken-Hoover J, Pallis M. Characterization of metacarpal fractures in a military population. Mil Med 2016; 181(8): 931-934.
• 9. Wolf JM, Dawson L, Mountcastle SB, Owens BD.  The incidence of scaphoid fracture in a military population. Injury 2009; 40(2):1316-1319.
• 10. Hsiao MS, Cameron KL, Huh J, Hsu JR, Benigni M, Whitener JC, Owens BD. Clavicle fractures in the United States military: incidence and characteristics. Mil Med 2012; 177(8):970-974.
• 11. Owens BD, Mountcastle SB, Dunn WR, et al. Incidence of anterior cruciate ligament injury among active duty U.S. military servicemen and servicewomen. Mil Med 2007;172(1):90-91.
• 12. Jones JC, Burks R, Owens BD, Sturdivant RX, Svoboda SJ, Cameron KL. Incidence and risk factors associated with meniscal injuries among active-duty US military service members.  J Athl Train 2012; 47(1):67-73.
• 13. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. NCAA data and review of literature. Am J Sports Med 1995; 23(6):694-701.
• 14. Zacchilli MA, Owens BD. Epidemiology of shoulder dislocations presenting to emergency departments in the United States. JBJS AM. 2010 Mar;92(3):542-9. doi: 10.2106/JBJS.I.00450.
• 15. Owens BD, Duffey ML, Nelson BJ, et al. The incidence and characteristics of shoulder instability at the United States Military Academy. Am J Sports Med 2007;35(7):1168-1173.
• 16. Waterman BR, Burns TC, McCriskin B, et al. Outcomes after bankart repair in a military population: predictors for surgical revision and long-term disability. Arthroscopy 2014; 30(2):172-177. doi: 10.1016/j.arthro.2013.11.004.