title: Differences in acromial morphology of shoulders in patients with degenerative and traumatic supraspinatus tendon tears.
abstract: OBJECTIVE
  Distinct characteristics of acromial morphology seem to be one factor for the development of degenerative supraspinatus tendon tears. Thus, it is questionable whether patients with traumatic tendon tears also present these parameters. The hypothesis of the present study was that the acromial morphology of patients with degenerative supraspinatus tendon tears differs from patients with traumatic tears.
  
  
  METHODS
  One hundred and thirty-six patients that were treated by arthroscopic rotator cuff repair from 2010 to 2013 were included in this study. Seventy-two patients had degenerative (group 1), and 64 had traumatic (group 2) supraspinatus tendon tears. On preoperative radiographs the Bigliani type, acromial slope, acromiohumeral (AH) distance, lateral acromial angle (LAA), acromion index (AI), and critical shoulder angle (CSA) were measured. Medians of these parameters as well as of age of both groups were compared using the t test.
  
  
  RESULTS
  The percentaged distribution of the Bigliani type differed (group 1 vs. 2: type 1: 18/38, type 2: 56/55, type 3: 26/8). All parameters showed significant differences between degenerative and traumatic tears. Slope: 21.2° (SD 7.6°) versus 19.2° (SD 7.9°, p = 0.026), AH distance: 8.4 mm (SD 2.3 mm) versus 9.9 mm (SD 1.9 mm, p = 0.0006), LAA: 77.0° (SD 4.0°) versus 82.5° (SD 4.7°, p < 0.0001), AI: 0.77 (SD 0.07) versus 0.73 (0.06, p = 0.0239), and CSA: 36.8° (SD 3.6°) versus 35.3° (SD 2.9°, p = 0.007). An LAA <70° or an AH distance of <5 mm only occurred in degenerative tears. Patients with degenerative tears were significantly older (60 vs. 54 years).
  
  
  CONCLUSIONS
  The hypothesis that the acromial morphology of patients with degenerative supraspinatus tendon tears differs from patients with traumatic tears was confirmed. Shoulders with degenerative tears show a narrower subacromial space and a larger lateral extension as well as a steeper angulation of the acromion than with traumatic tears. Thus, the results of this study support the theory of external impingement as a cause for degenerative rotator cuff tears.
  
  
  METHODS
  IV.
authors.affiliation: Sportsclinic Cologne, Cologne-Merheim Medical Center, University of Witten-Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany. maurice.balke@gmail.com.|Department of Trauma and Orthopaedic Surgery, Cologne-Merheim Medical Center, University of Witten-Herdecke, Cologne, Germany. maurice.balke@gmail.com.
authors.forename: Maurice
authors.initials: M
authors.lastname: Balke
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Muenster, Münster, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Liem
authors.affiliation: Sportsclinic Cologne, Cologne-Merheim Medical Center, University of Witten-Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Greshake
authors.affiliation: Sportsclinic Cologne, Cologne-Merheim Medical Center, University of Witten-Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Hoeher
authors.affiliation: Department of Trauma and Orthopaedic Surgery, Cologne-Merheim Medical Center, University of Witten-Herdecke, Cologne, Germany.
authors.forename: Bertil
authors.initials: B
authors.lastname: Bouillon
authors.affiliation: Department of Trauma and Orthopaedic Surgery, Cologne-Merheim Medical Center, University of Witten-Herdecke, Cologne, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Banerjee
mesh_terms: D000174:Acromion / Q000000981:diagnostic imaging*; D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017006:Rotator Cuff / Q000000981:diagnostic imaging*; D000070636:Rotator Cuff Injuries / Q000000981:diagnostic imaging*; D000070599:Shoulder Injuries / Q000000981:diagnostic imaging*
keywords: Acromial morphology; Bigliani; Rotator cuff tear; Shoulder trauma; Subacromial decompression