3-D Statistical Shape Model of the Humerus Towards Artificial Shoulder Joint Design

Currently, the humeral head portion of the artificial shoulder joint is usually designed by approximating it to a sphere or an ellipse. The differences between the approximated shape and the actual shape of the humeral head could limit the shoulder motion. Toward artificial shoulder joint design, this study introduces a method of constructing a 3-D statistical shape model (SSM) of the humeral head from a set of healthy subjects with CT images of the shoulder. Firstly, the humerus region is segmented from CT images, and then the anatomical coordinate system of the segmented humerus regions is determined. Secondly, each humerus region is aligned to a common reference space by using the determined anatomical coordinate system of the humeral head. Finally, 3-D SSM of the humeral head is constructed by applying principal component analysis to the aligned images. The method was validated by generalization ability, and satisfactory outcome was obtained which reveals its potential applicability toward artificial shoulder joint design in future.