Shape model analysis of THR radiographs

We describe a system that performs fully automatic analysis of total hip replacement (THR) radiographs using a model-based approach. Previous methods for analysis of this type of radiograph have been manual or semi-automatic and require considerable investment of skilled operators time. Our system works unsupervised and is the first of its type. Image search is carried out using a statistically defined deformable template used as an active shape model (ASM). The ASM, which is trained to model prosthetic, femoral, and pelvic structures within the image, iteratively modifies its pose and shape to fit to the evidence in a given image. We present the results of systematic experiments which show that the system can robustly locate relevant structures in routine post-operative radiographs accurately enough for practical applications.