A 3D-CT scan study of the humeral and glenoid planes in 150 normal shoulders

The purpose of the study was to determine the normal three-dimensional relationship between the humeral and the glenoid plane of the individual patient. We measured the three-dimensional angle between the glenoid plane and the humeral plane (glenohumeral angle, °GH) and the angle between the plane of the scapula and the plane of the glenoid (glenoscapular angle, °GS) with the patient in a standardized position to the CT scan gantry. We hypothesized that a normal distribution with a small variation would exist for both angles.

A total of 150 conventional CT scans of normal shoulders from patients aged between 18 and 80 years were examined and three-dimensional reconstructions were derived from it. The descriptive statistics and the variability of °GH and °GS were determined.

The mean °GH was 57.9°, and the mean °GS was -3.77°. The overall reliability of the measurement was good. Descriptive statistics of this study confirm the normal distribution and a narrow variation of both parameters.

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.