Two fluoroscopic images taken from two different angles of the same anatomical feature are registered to a common three-dimensional coordinate system. A dimension of the anatomical feature is determined by specifying with reference to the two registered fluoroscopic images two constrained points within the three-dimensional coordinate system that correspond to the boundaries of the anatomical feature, and calculating a straight-line distance between the two. Additionally, a three-dimensional virtual model of an implant is projected into each of two, registered fluoroscopic image, and a surgeon manipulates the projections to adjust the size and shape of the virtual model, and thereby determine parameters for the implant.