title: Incidence and Characteristics of Traumatic Shoulder Instability in Japanese Military Cadets.
abstract: Little is known regarding the incidence of the shoulder instability in Japan. The aim of this study was to evaluate the incidence of traumatic shoulder instability among Japanese military cadets. A prospective cohort study was performed to capture all traumatic shoulder instability events between 2009 and 2012 among cadets in a military educational academy of the Japan Self Defense Forces. The total number of cadets in the cohort was 5,402 (average age 20.6 years). The incidence of instability events, including dislocation or subluxation, was calculated. Chronicity, demographics of participants, mechanism of injury, and athletic events were also evaluated. The incidence of traumatic dislocation was 4.1/1,000 person-years and that of subluxation was 6.1/1,000 person-years. The incidence of primary dislocation or subluxation was 5.4/1,000 person-years and that of recurrent dislocation or subluxation was 4.7/1,000 person-years. Of first dislocations or subluxations, 92% occurred during sports activities, including after-school sports activities, military training, and gym classes. In conclusion, the overall incidence of shoulder instability events among Japanese military cadets was 10.3/1,000 person-years, and was extremely high. Most shoulder instability events occurred during sports activities, and a program to prevent such injuries during sports activities is necessary for young participants.
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Amako
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasao
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Matsuhashi
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Yato
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshihara
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Arino
authors.affiliation: Department of Preventive Medicine and Public Health, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sakurai
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Nemoto
mesh_terms: D000293:Adolescent; D001265:Athletic Injuries / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D004204:Joint Dislocations / Q000150:complications; D007593:Joint Instability / Q000453:epidemiology*; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012307:Risk Factors; D000070599:Shoulder Injuries; D055815:Young Adult