Hypothesis: The purpose of this study was to investigate the three dimensional orientation of the glenoid plane and the scapular plane. Different definitions of the glenoid plane were used and different planes were measured and we hypothesed that the 3-D plane with the least variation would be best to define the most reliable glenoid plane. Methods: We studied 150 CT scans from non-pathological shoulders from patients between 18 and 80. The scapular plane and five different glenoid planes were determined: an inferior, anterior, posterior, superior and neutral glenoid plane. Of all planes version and inclination angles were measured. Because all examinations were done in a standardized position to the coronal, sagittal and transverse plane of the body the scapular plane could be defined versus the coronal, sagittal and transverse planes of the body. Results: The version (mean: 3.76) of the inferior glenoid plane showed a significantly lower standard deviation than the version of the anterior (p<0.001), posterior (p=0.001) and superior (p=0.001) glenoid plane (ANOVA). For inclination all planes have a similar variance. The scapular plane was different between gender ( P=0.022) and correlated with age. Conclusion: This 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. Revision of the MS. Ref. No.: JSES-D-09-00274Comments from the Editors and Reviewers: Associate Editor's comment: Unfortunately the reviewer are not convinced that this study adds much useful new data to literature. Weak points are: Indication for CT scan examination of the contralateral shoulder not given: The patients that were included had a CT scan examination of the contralateral (pathologic) shoulder for instability (30), AC-joint arthritis (33), Rotator Cuff tears (33), (partial (5), Full thickness (28)), calcifying tendinitis (12), frozen shoulder (8), subacromial impingement (17), tendinitis of the long head of biceps brachii (12), fractures of the proximal humerus (5). Those pathologies are included in the manuscript.A special selection (Instability, osteoarthritis, cuff tear arthropathy) might have influenced the results. This is a study about the normal shoulder and we hope to do in the future studies on the pathological shoulder as one might expect this might differ from the normal shoulder. The clinical examination of the shoulder as well as the history was negative of the included shoulder and this is mentioned in the manuscript.Ethical considerations: Was the consensus of the patients for the scan of the contralateral shoulder and the ethical committee given (difference of exposure both versus one shoulder?). Ethical approval was cleared from the ethics committee (EC/2009-099/Svdm). The patients received no extra irradiation because it is difficult to impossible to positioning one shoulder more central in the CT-scan to narrow the window of exposure an...

This is the first study to determine the normal 3D relationship between the humerus and the glenoid (°GH). This new three-dimensional anatomical information of the normal glenohumeral relationship and glenoid can be used to distinguish normal from pathological anatomy, as well as alternative surgical guidance especially in bony deficient glenoids. Level of Evidence Level II Anatomical Study.

No abstract