title: Re-examining the association of os acromiale with supraspinatus and infraspinatus tears.
abstract: OBJECTIVE
  To re-evaluate the relationship between os acromiale and rotator cuff tears.
  
  
  METHODS
  We retrospectively analyzed 84 magnetic resonance imaging studies of the shoulder. Forty-two subjects with os acromiale (n = 42; 32 men and ten women, age 25-81 years, mean 47.6 years) were compared with age- and gender-matched subjects with no evidence of os acromiale (controls). Arthroscopy data were available in 19 os acromiale and 12 control subjects. Statistical analyses were performed to determine differences between groups regarding rotator cuff tears affecting the supraspinatus and infraspinatus tendons detected by magnetic resonance imaging and arthroscopy. Analysis of os acromiale type, ossicle synchondrosis edema, acromioclavicular joint degenerative changes and step-off deformity at the synchondrosis were tabulated.
  
  
  RESULTS
  No statistically significant difference between the os acromiale and control groups was noted, either on magnetic resonance imaging or arthroscopy, with regard to tears of the supraspinatus (P = 1.000 and 0.981, respectively) and infraspinatus (P = 1.000 and 0.667, respectively) tendons. There was a statistically significant increased number of supraspinatus (P = 0.007) and infraspinatus (P = 0.03) tears in a comparison of subjects with os acromiale and step-off deformity (10/42) vs os acromiale without step-off deformity (32/42).
  
  
  CONCLUSIONS
  The presence of os acromiale may not significantly predispose to supraspinatus and infraspinatus tendon tears. However, subjects with step-off deformity of an os acromiale are at greater risk of rotator cuff tears than are similar subjects without such deformity.
authors.affiliation: Musculoskeletal Radiology, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, YAW-6046, Boston, MA 02114, USA. haouellette@partners.org
authors.forename: H
authors.initials: H
authors.lastname: Ouellette
authors.forename: B J
authors.initials: BJ
authors.lastname: Thomas
authors.forename: A
authors.initials: A
authors.lastname: Kassarjian
authors.forename: B
authors.initials: B
authors.lastname: Fritz
authors.forename: P
authors.initials: P
authors.lastname: Tétreault
authors.forename: W E
authors.initials: WE
authors.lastname: Palmer
authors.forename: M
authors.initials: M
authors.lastname: Torriani
mesh_terms: D000174:Acromion / Q000002:abnormalities* / Q000000981:diagnostic imaging* / Q000293:injuries; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001182:Arthroscopy; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000473:pathology; D000070636:Rotator Cuff Injuries; D012737:Sex Factors