Shoulder impingement in the United States military.

BACKGROUND: Little is known about the incidence and characteristics of primary, or external, shoulder impingement in an occupationally and physically active population. A longitudinal, prospective epidemiologic database was used to determine the incidence and risk factors for shoulder subacromial impingement in the United States (U.S.) military. Our hypothesis was that shoulder impingement is influenced by age, sex, race, military rank, and branch of service. METHODS: The Defense Medical Epidemiology Database was queried for all shoulder impingement injuries using International Classification of Disease, Ninth Addition, Clinical Modification code 726.10 within a 10-year period from 1999 through 2008. An overall injury incidence was calculated, and a multivariate analysis performed among demographic groups. RESULTS: In an at-risk population of 13,768,534 person-years, we identified 106,940 cases of shoulder impingement resulting in an incidence of 7.77/1000 person-years in the U.S. military. The incidence of shoulder impingement increased with age and was highest in the group aged ≥40 years (incidence rate ratio [IRR], 4.90; 95% confidence interval [CI], 4.61-5.21), was 9.5% higher among men (IRR, 1.10, 95% CI, 1.06-1.13), and compared with service members in the Navy, those in the Air Force, Army, and Marine Corps were associated with higher rates of shoulder impingement (IRR, 1.46 [95% CI, 1.42-1.50], 1.42 [95% CI, 1.39-1.46], and 1.31 [95% CI, 1.26-1.36], respectively). CONCLUSIONS: The incidence of shoulder impingement among U.S. military personnel is 7.77/1000 person-years. An age of ≥40 years was a significant independent risk factor for injury.

Clavicle fractures in the United States military: incidence and characteristics.

BACKGROUND: Although it is generally known that clavicle fractures represent a common injury of the shoulder girdle in the general population, the true incidence in the active duty military population is unknown. Given the implications for such injuries on the ability to perform occupation-specific tasks, determining the incidence in the U.S. military population is worthwhile. The purpose of this study was to determine the incidence of clavicle fractures in the U.S. military and to identify any demographic risk factors for injury. METHODS: We performed a query of the Defense Medical Epidemiology Database with the code from the International Classification of Diseases, Ninth Revision, for clavicle fractures for the years 1999 through 2008. An overall injury incidence was calculated, in addition to multivariate analysis, to determine independent risk factors among the following demographic considerations: sex, race, branch of military service, rank, and age. RESULTS: During the study period, a total of 12,514 clavicle fractures were documented among an at-risk population of 13,770,767 person-years for an incidence rate (IR) of 0.91 per 1,000 person-years in the U.S. Military. Males, when compared with females, were more than twice as likely to sustain a clavicle fracture (IR ratios [IRR], 2.30; 95% confidence intervals [CI], 2.12-2.49). The peak incidence of clavicle fractures occurred in the age groups of <20 and 20 to 24. Compared to black service members, the white service members were associated with significantly higher rate of clavicle fractures (IRR, 2.45; 95% CI, 2.28-2.63). The service members serving in the Marine Corps were associated with a higher IR of clavicle fractures when compared to those in the Navy (IRR, 1.44; 95% CI, 1.35-1.53). Junior enlisted service members were 34% as likely to sustain a clavicle fracture when compared to senior officers (IRR, 1.46; 95% CI, 1.34-1.60 and IRR, 1.12; 95% CI, 0.99-1.28, respectively). CONCLUSIONS: The incidence of clavicle fractures among U.S. military personnel (0.908 per 1,000 person-years) is higher than previous epidemiological reports.

Online extremism and the communities that sustain it: Detecting the ISIS supporting community on Twitter.

The Islamic State of Iraq and ash-Sham (ISIS) continues to use social media as an essential element of its campaign to motivate support. On Twitter, ISIS' unique ability to leverage unaffiliated sympathizers that simply retweet propaganda has been identified as a primary mechanism in their success in motivating both recruitment and "lone wolf" attacks. The present work explores a large community of Twitter users whose activity supports ISIS propaganda diffusion in varying degrees. Within this ISIS supporting community, we observe a diverse range of actor types, including fighters, propagandists, recruiters, religious scholars, and unaffiliated sympathizers. The interaction between these users offers unique insight into the people and narratives critical to ISIS' sustainment. In their entirety, we refer to this diverse set of users as an online extremist community or OEC. We present Iterative Vertex Clustering and Classification (IVCC), a scalable analytic approach for OEC detection in annotated heterogeneous networks, and provide an illustrative case study of an online community of over 22,000 Twitter users whose online behavior directly advocates support for ISIS or contibutes to the group's propaganda dissemination through retweets.