Assessment of Center of Rotation of the Glenohumeral Joint

During a total shoulder replacement the glenohumeral joint is substituted by a prosthesis. The joint is a loose ball-and-socket joint, in which the humeral head is the ball and the glenoid is the socket. Most important for successful surgery is that the position of the center of rotation of the glenohumeral joint is maintained [1]. During motion, the two geometric centers of both spherical articular surfaces coincide [1] in the center of rotation of the glenohumeral joint. In this paper we present a new technique to automatically determine the 3D center of a sphere in 3D images, using the direction and strength of the gradient.