A polygonal model of the distal femur, created directly from the segmented CT data, has been fit with condylar cylinders. Their axis, and the epicondylar axis are shown. This image, taken from an Interative Anatomic Animation (IAAs), illustrates that the condylar and epicondylar axes are not identical. IAAs provide user interaction and encourage the user to manipulate the models in order gain a full understanding of the functional anatomy.