Abnormal glenoid version positioning has been recognized as a cause of glenoid component failure caused by the rocking horse phenomenon. In contrast, the importance of the glenoid inclination has not been investigated. The computed tomography scans of 152 healthy shoulders were evaluated. A virtual glenoid component was positioned in 2 different planes: the maximum circular plane (MCP) and the inferior circle plane (ICP). The MCP was defined by the best fitting circle of the most superior point of the glenoid and 2 points at the lower glenoid rim. The ICP was defined by the best fitting circle on the rim of the inferior quadrants. The inclination of both planes was measured as the intersection with the scapular plane. We defined the force vector of the rotator force couple and calculated the magnitude of the shear force vector on a virtual glenoid component in both planes during glenohumeral abduction.BACKGROUND
MATERIALS AND METHODS
The balance between the subscapularis muscle and the infraspinatus/teres minor muscles, often referred to as the rotator cuff ‘force couple’, has been proposed to be critical component for glenohumeral stability. Function of these muscles can be estimated with the evaluation of muscle atrophy. In clinical practice, muscle cross-sectional area (CSA) rather than 3D muscle volume measurement have been used because it is less time consuming. Because combined anthropometric measures of length and width more accurately define the muscular volume it seems logical to study the transversal rotator cuff force couple in the transversal plane an not in the sagittal plane of the body because both parameters can be included. But is it not clear which transversal CSA has the best correlation with muscle volume To determine the optimal transversal CSA that has the best correlation with muscle volume.Background:
Purpose:
Humeral head subluxation in patients with cuff tear arthropathy (CTA) and in patients with primary arthrosis has been classified by Hamada and by Walch (type B). These classifications are based on 2D evaluation techniques (AP X-ray view, axial CT images). To our knowledge no 3D evaluation of the direction of humeral head subluxation has been described To describe a reproducible 3D measuring technique to evaluate the direction of the humeral head subluxation in shoulder arthropathyIntroduction
Aim
