title: Prevalence and risk factors of a rotator cuff tear in the general population.
abstract: BACKGROUND
  Little information is available about the epidemiology of rotator cuff tears in a population-based study. The purpose of this study was to elucidate the true prevalence of rotator cuff tears regardless of the presence or absence of symptoms in the general population and to assess the relationship between tears and their backgrounds.
  
  
  METHODS
  A medical check-up was conducted for residents of a mountain village in Japan. The subjects consisted of 683 people (total of 1,366 shoulders), including 229 males and 454 females with a mean age of 57.9 years (range, 22-87). We examined their background factors, physical examinations and ultrasonographic examinations on both shoulders.
  
  
  RESULTS
  Rotator cuff tears were present in 20.7% and the prevalence increased with age. Thirty-six percent of the subjects with current symptoms had rotator cuff tears, while 16.9% of the subjects without symptoms also had rotator cuff tears. Rotator cuff tears in the general population were most commonly associated with elderly patients, males, affected the dominant arm, engaged in heavy labor, having a history of trauma, positive for impingement sign, showed lesser active forward elevation and weaker muscle strength in abduction and external rotation. A logistic regression analysis revealed the risk factors for a rotator cuff tear to be a history of trauma, dominant arm and age.
  
  
  CONCLUSIONS
  20.7% of 1,366 shoulders had full-thickness rotator cuff tears in the general population. The risk factors for rotator cuff tear included a history of trauma, dominant arm and age.
  
  
  METHODS
  Level 3.
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunman, Japan. a.yamamoto@gunma-u.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Takagishi
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Osawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Yanagawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nakajima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shitara
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kobayashi
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D006306:Health Surveys; D006801:Humans; D015601:Injury Severity Score; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010147:Pain Measurement; D010808:Physical Examination / Q000379:methods; D015995:Prevalence; D011336:Probability; D011379:Prognosis; D016059:Range of Motion, Articular / Q000502:physiology*; D018570:Risk Assessment; D000070636:Rotator Cuff Injuries; D017678:Sex Distribution; D013708:Tendon Injuries / Q000000981:diagnostic imaging / Q000453:epidemiology*; D014463:Ultrasonography; D055815:Young Adult