title: Glenoid Rim Anatomy: Risk for Glenoid Vault Perforation During Labral Repair.
abstract: BACKGROUND
  Injuries to the glenoid labrum frequently require repair with anchors. Placing anchor devices arthroscopically can be challenging, and anchor malpositioning can complicate surgical outcomes.
  
  
  OBJECTIVE
  To determine the safe insertion range and optimal insertion angle of glenoid labral anchors at various positions on the glenoid rim and to establish surgical guidelines that minimize risk of anchor perforation.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Three-dimensional computed tomography scans of 30 normal cadaveric specimens were obtained. A virtual model of a generic labral anchor was inserted into the rim of the glenoid at the clockface positions represented by 12:00, 1:30, 3:00, 4:30, 6:00, 7:30, 9:00, and 10:30. At each position, the safe insertion range was the maximal range measured, and the optimal insertion angle was identified as the angle between the bisector of the safe insertion range and the glenoid face.
  
  
  RESULTS
  Progressing in the clockwise direction, beginning at the 12:00 position, the safe insertion ranges (mean ± SD ) were 55.9° ± 10.6°, 63.6° ± 17.6°, 47.7° ± 9.1°, 46.1° ± 8°, 73.9° ± 9.7°, 40.9° ± 6.5°, 40.4° ± 7.4°, and 39.9° ± 7.1°, respectively. The optimal insertion angles were 47.9° ± 7.6°, 53.1° ± 10.9°, 35.0° ± 4.4°, 42.4° ± 4.9°, 60.9° ± 8.4°, 36.6° ± 5.9°, 31.2° ± 4.9°, 34.8° ± 4.6°, respectively.
  
  
  CONCLUSIONS
  Optimal insertion angles and safe insertion ranges varied significantly with respect to the position on the glenoid face. The safe insertion range and optimal insertion angle were found to be wider at the anterior glenoid as compared with the posterior glenoid. A posterolateral insertion angle was safer than an anterior insertion angle at the 10:30 position.
  
  
  CONCLUSIONS
  Proper arthroscopic technique resulting in anchor insertion at the correct angle, depth, and location will prevent anchor-related glenohumeral complications such as glenoid perforation, cartilage damage, persistent pain, decreased range of motion, and failure of the reconstruction.
authors.affiliation: Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, California, USA.
authors.forename: Yadin D
authors.initials: YD
authors.lastname: Levy
authors.affiliation: St Luke's Northland Hospital, Kansas City, Missouri, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Williamson
authors.affiliation: Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, California, USA.
authors.forename: Cesar
authors.initials: C
authors.lastname: Flores-Hernandez
authors.affiliation: Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, California, USA.
authors.forename: Darryl D
authors.initials: DD
authors.lastname: D'Lima
authors.affiliation: Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, California, USA.
authors.forename: Heinz R
authors.initials: HR
authors.lastname: Hoenecke
keywords: anchor; computer model; glenoid labrum; labral repair; labral tear; shoulder arthroscopy; virtual surgery