ABSTRACT
PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
Subject(s)
Humerus/anatomy & histology , Imaging, Three-Dimensional/methods , Shoulder Joint/anatomy & histology , Tomography, X-Ray Computed/methods , Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Humerus/diagnostic imaging , Male , Middle Aged , Observer Variation , Reference Values , Reproducibility of Results , Shoulder Joint/diagnostic imaging , Young AdultABSTRACT
HYPOTHESIS: The tuberosities of the proximal humerus relate geometrically to the humeral head in an anteroposterior symmetry. MATERIAL AND METHODS: Twenty-eight cadaveric shoulders were scanned with computed tomography and reconstructed digitally in 3 dimensions. On both tuberosities, 5 facets were identified. An orthogonal planar system using the center of the humeral head as its origin was created to calculate the coordinates of the centre of each facet. The angular position of the center of each facet was measured with reference to the sagittal plane. The inclination of each facet was measured to the axial plane. RESULTS: The presence of 5 distinct facets with a different inclination was confirmed (lesser tuberosity: inferior facet: 77.8° [sd 7.8°]; superior facet: 50.3° [sd 9.3°] - greater tuberosity: superior facet: 20.4° (sd 5.6°); middle facet: 48.6° (sd 5.2°); inferior facet: 92.7° [sd 7.7°]). The angular position of the centers of the facets was less variable (lesser tuberosity: inferior facet: 22.6° [sd 4.3°]; superior facet: 39.2° [sd 4.4°] - greater tuberosity: superior facet: 89.9° [sd 5.9°]; middle facet: 131.6° [sd 6.1°]; inferior facet: 155.1° [sd 6.8°]). CONCLUSION: Our study contributes to the knowledge of the anatomy of the proximal humerus, more specifically of the position of the rotator cuff insertion in relation to the humeral head. These insights are useful in the development of shoulder trauma prostheses.
