Image analysis for computer-assisted internal fixation of hip fractures

This paper focuses on the task of automatic feature detection for intra-operative drilling trajectory planning for computer-assisted internal fixation of hip fractures. The features of interest are the lateral cortex line of the femoral shaft, the femoral neck centre and the femoral head centre, the latter being the most challenging of all. Since the object is known, the detection process is regarded as a localisation task rather than a recognition one. Simple anatomical relationships between bone parts provide a naturally hierarchical approach to searching, allowing refinement of image-derived information based on a priori constraints. Use of knowledge and an unconventional “divide-and-conquer” approach produce more reliable and faster results than the standard global image processing routine. Analysis of summed 1D grey level profiles is used as a main segmentation tool to carry out the above strategy.