In this work we present a method for automated orthopaedic measurements for patients that have undergone a partial or full joint replacement in the lower limbs. In contrast to previously published approaches for partially occluded objects, we deal with objects were the major part of the contour is missing, namely the epiphyses of the long bones in the lower limbs, that have been replaced in large parts by artificial joint implants of varying appearance. We present an approach based on the automatic detection and segmentation of implants and a robust adaptation of a segmentation technique based on deformable models. We evaluated our method on a set of clinical images and achieve an accuracy of 0.6° for angles and 1.3 mm for lengths measurements while significantly reducing assessment time and eliminating user interaction.
