Anatomical coordinate systems for high-resolution scapula and humerus models

Bio-imaging techniques represent a powerful tool for high resolution joint biomechanical analysis. A main limitation of the latter techniques is related to the restricted field of view (FOV) which may prevent the acquisition of the complete bone model. Specifically, in shoulder MR clinical images, only the proximal portions of the humerus (h) and the scapula (s) are visible. The anatomical coordinate system (ACS) definitions proposed by the ISB for s and h, requiring the identification of anatomical landmarks (ALs) located on distal portions of the bones can be rarely used in medical imaging applications. Alternative ACS definitions for high-resolution images of s and h have been proposed [2] and [3]. However, the methodology proposed by Sahara and colleagues (2007) is fairly difficult to implement and requires manual adjustments. Conversely, the definitions proposed by Amadi and colleagues (2008) require the identification of anatomical regions which are not easy to identify from MRI and that could not be included in the FOV. The aim of this study is to propose ACS definitions for s and h applicable to MRI, characterized by limited FOV and relying on easy to identify ALs.