title: Accuracy of measurement of Hill-Sachs lesions with computed tomography.
abstract: BACKGROUND
  Bone defects play a role in recurrent instability. There is no universal method to quantify humeral head defects. The purpose of this study is to assess the accuracy of 2-dimensional computed tomography (CT) scan measurements of Hill-Sachs lesions.
  
  
  METHODS
  Six Hill-Sachs defects were created in anatomically shaped bone substitutes. The samples were scanned with a 3-dimensional laser scanner. Maximum width and depth were measured and used as the true measurement. The samples underwent routine CT scanning, and 5 physicians measured maximum width and depth on each plane independently. The intraclass correlation coefficient (ICC) was used to assess agreement. Percent error and paired t test were used for statistical analysis (P < .05 denoted significance).
  
  
  RESULTS
  The ICC between observers was 0.879 (95% confidence interval, 0.780-0.946) and 0.721 (95% confidence interval, 0.543-0.865) for the depth and width measurement, respectively. The ICC was good between individual observers and the true measurement (range, 0.765-0.956). Individual observers were more accurate in depth rather than width measurements. The mean overall percent error of the depth and width measurements for the 6 defects was calculated: coronal, 19.2% ± 13.6%; sagittal, 11.8% ± 8.2%; and axial, 13.6% ± 8.4%.
  
  
  CONCLUSIONS
  The depth of Hill-Sachs lesions can be reliably assessed using CT scan. Observers consistently underestimated width in all imaging planes. Overall, sagittal- and axial-plane measurements are more accurate for evaluation of these defects than the coronal plane. Future studies using 3-dimensional CT may be helpful to further quantitatively assess the size of the Hill-Sachs lesion, including width and volume.
authors.affiliation: Department of Orthopaedic Surgery, University of Texas Health Sciences Center, Houston, TX, USA.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kodali
authors.forename: Morgan H
authors.initials: MH
authors.lastname: Jones
authors.forename: Josh
authors.initials: J
authors.lastname: Polster
authors.forename: Anthony
authors.initials: A
authors.lastname: Miniaci
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Fening
mesh_terms: D006801:Humans; D058430:Humeral Head / Q000000981:diagnostic imaging / Q000293:injuries*; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology; D008953:Models, Anatomic; D015203:Reproducibility of Results; D012783:Shoulder Dislocation / Q000150:complications / Q000000981:diagnostic imaging*; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*