title: Arthroscopic lateral acromion resection (ALAR) optimizes rotator cuff tear relevant scapula parameters.
abstract: BACKGROUND
  The acromion index (AI), critical shoulder angle (CSA) and lateral acromion angle (LAA) are predictive for degenerative rotatory cuff tears. Their unfavorable values are associated with a suboptimal deltoid force vector. The aim of this study was to evaluate whether an optimization of the radiological parameters could be achieved through a specific arthroscopic lateral acromion resection (ALAR).
  
  
  METHODS
  The procedure was performed in eight fresh frozen cadaver shoulders. True a.p. and axial radiographs were taken before and after the intervention for radiological evaluation. The anterior and posterior acromion edges were marked with a spinal needle. Then 1 cm of the lateral acromion was resected with a 5.0 acromionizer (Arthrex Inc., Naples, FL, USA) beginning from the anterior aspect. The resection was completed over the total width of 1 cm from anterior to posterior. Finally the deltoid insertion was dissected via an open approach to ensure its integrity. The fluoroscopy images were evaluated regarding the pre- and postinterventional parameters AI, CSA and LAA.
  
  
  RESULTS
  After the intervention, the mean AI could be significantly reduced from 0.62 ± 0.11 to 0.40 ± 0.15 (p = 0.012). Also the mean CSA was significantly reduced from 35.0° ± 7.65° to 25.12° ± 8.29° (p = 0.018). The LAA could not be significantly changed (76.5° ± 14.02° vs. 82.13 ± 8.93; p = 0.107). There was no injury to the deltoid insertion.
  
  
  CONCLUSIONS
  The radiographic parameters AI und CSA can be optimized significantly by ALAR without macroscopic discontinuity of the deltoid insertion.
  
  
  METHODS
  Level IV, case series without comparison group.
authors.affiliation: Sporthopaedicum Regensburg, Hildegard-von-Bingen-Str. 1, 93053, Regensburg, Germany.
authors.forename: Burak
authors.initials: B
authors.lastname: Altintas
authors.affiliation: Sporthopaedicum Regensburg, Hildegard-von-Bingen-Str. 1, 93053, Regensburg, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Kääb
authors.affiliation: Sporthopaedicum Regensburg, Hildegard-von-Bingen-Str. 1, 93053, Regensburg, Germany. greiner@sporthopaedicum.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Greiner
mesh_terms: D000174:Acromion / Q000000981:diagnostic imaging / Q000601:surgery*; D001182:Arthroscopy / Q000379:methods*; D002102:Cadaver; D057645:Deltoid Muscle; D005471:Fluoroscopy; D006801:Humans; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries / Q000601:surgery*; D012540:Scapula / Q000000981:diagnostic imaging; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*
keywords: Acromial morphology; Acromion index; Arthroscopic acromion resection; Critical shoulder angle; Lateral acromion angle; Rotator cuff disease; Scapular anatomy