Determination of Elbow Flexion-Extension Axis Based on Planar and Closed B-Splines

Abstract

Accurate determination of the flexion-extension axis of the elbow affects the outcome of implant replacement. The current study proposes an automated approach capable of determining the FE axis based on a stack of axial computer tomographic (CT) imaging slices of the distal humerus. The core of the algorithm consists of an original technique employing control polygon deformation used to approximate the segmented outer cortical bone points with closed B-Splines, followed by curvaturebased and least squares fitting methods for determination of the two relevant geometric centers. The new approach was validated against a conventional voxelbased FE axis determination procedure involving marching cubes algorithm.