Computer-Aided Modeling and Morphological Analysis of Hip Joint

The accurate model of hip joint plays an important hole in the navigation system about the treatment to hip arthroplasty, femoral prostheses, or a total hip replacement. This paper focuses on the automatic reconstruction of femur and pelvic bone from CT dataset. A new method of using CT images combined with the reverse engineering technique is presented. Three-dimensional models of femur and pelvic bone are reconstructed from the CT images. A fitting algorithm that is the optimal least squares spherical approximation to a 3D point cloud, was applied to derive the geometrical data of the femoral head portion and the acetabulum portion respectively. Some parameters for hip joint, such as femoral head diameter, femoral head center and the radius of acetabulum, et al. can be calculated automatically according to the fitting sphere. By analyzing the fitting geometrical shape and its original shape, we found that the surface of femoral head and acetabulum are proximal sphere and their spherical centers are almost superposition, which is coincident with their anatomy structure. The proposed method was successfully applied to 10 sets of in vivo CT data of normal volunteers and actual patients.