title: Comparison of two different measurement methods to determine glenoid bone defects: area or width?
abstract: BACKGROUND
  This study compared two different techniques that have been used to measure the glenoids of patients with recurrent anterior shoulder dislocation.
  
  
  METHODS
  We analyzed 36 patients who had received arthroscopic Bankart repair for anterior shoulder instability. Retrospectively, 3-dimensional computed tomography images of both shoulders were available for these patients. Two measurement methods were compared to determine the glenoid defects. One of these techniques is based on linear measurement, previously defined as the glenoid index. The other method is based on surface area measurement. Subsequently, 3 more diameters and the average values obtained from these diameters were compared with the surface measurement method. Pearson correlation coefficient (r) was assessed to determine the relationship.
  
  
  RESULTS
  There was an almost perfect relationship between measurement methods when the defect area was less than 6% of the inferior glenoid circle (r, 0.915; P < .001). This relation decreased and the difference became more pronounced (r, 0.343; P = .657) when the bone loss exceeded 14% of the inferior glenoid circle. The highest correlations with the actual defects were the average values obtained from 4 different diameters (r, 0.964; P < .001) and the 4-o'clock position of the single diameter measurements (r, 0.860; P = .001). In addition, 11 patients had crescent-like defects, demonstrating a relatively low correlation between the measurement methods (r, 0.679; P = .021).
  
  
  CONCLUSIONS
  Although the best correlation was achieved from average values obtained from different diameter positions, in practical use, we advise a linear measurement to estimate the glenoid bone loss at the 4-o'clock position to achieve a high correlation between the measurement techniques.
authors.affiliation: Orthopaedics and Traumatology Department, Selcuk University Medical Faculty, Konya, Turkey. Electronic address: egemenaltan@hotmail.com.
authors.forename: Egemen
authors.initials: E
authors.lastname: Altan
authors.affiliation: Orthopaedics and Traumatology Department, Acibadem University, Istanbul, Turkey.
authors.forename: Mehmet Ugur
authors.initials: MU
authors.lastname: Ozbaydar
authors.affiliation: Orthopaedics and Traumatology Department, Namik Kemal University, Tekirdag, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Tonbul
authors.affiliation: Manus Hand Surgery Center, Istanbul, Turkey.
authors.forename: Levent
authors.initials: L
authors.lastname: Yalcin
mesh_terms: D000328:Adult; D000368:Aged; D001862:Bone Resorption / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D012008:Recurrence; D012189:Retrospective Studies; D012540:Scapula / Q000000981:diagnostic imaging* / Q000473:pathology; D012783:Shoulder Dislocation / Q000000981:diagnostic imaging* / Q000601:surgery; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed
keywords: Glenoid bone loss; Pico method; arthroscopy; glenoid index; instability; shoulder