Reliability of the glenoid plane

HypothesisThe purpose of this study was to investigate the 3-dimensional (3-D) orientation of the glenoid and scapular planes. Different definitions of the glenoid plane were used and different planes measured, and we hypothesed that the 3-D plane with the least variation would be best to define the most reliable glenoid plane.MethodsWe studied 150 CT scans from nonpathological shoulders from patients between 18 and 80. The scapular plane and 5 different glenoid planes were determined: inferior, anterior, posterior, superior, and neutral. All plane versions and inclination angles were measured. Because all examinations were done in a standardized position to the coronal, sagittal, and transverse planes of the body, the scapular plane could be defined versus the coronal, sagittal, and transverse planes of the body.ResultsThe version (mean, 3.76) of the inferior glenoid plane showed a significantly lower standard deviation than the version of the anterior (P < .001), posterior (P = .001), and superior (P = .001) glenoid plane (ANOVA). For inclination all planes have a similar variance. The scapular plane was different between gender (P = .022) and correlated with age.ConclusionThis study showed that the retroversion of the inferior glenoid is reasonably constant. The osseous anthropometry of the inferior glenoid can offer a reproducible point of reference to be used in prosthetic surgery of the shoulder.