Analytical Reconstruction of the Human Pelvis In-Vitro Using Photogrammetry and Magnetic Resonance Imaging

Accurate methods for determination of the hip centre and other geometric quantities has become a major concern when analyzing human movement. As part of an ongoing study on acetabular contact pressures using a pressure instrumented femoral endoprosthesis, we have recovered the acetabulum and prosthesis from a recently deceased subject from our study in order to improve our knowledge of the subject’s anatomy for reprocessing and interpretation of our in-vivo data. To evaluate the human locomotor motions and forces, the locations of the attachments of soft tissue to bone and the orientation and geometry of the articular surfaces must be measured accurately. The problem is compounded when trying to orient a hemi-(half) pelvis. We propose a method for measuring separately the geometry of a left and right hemi-pelvis and joining the two halves to represent the entire pelvis. We also propose a method by which the geometry of the acetabulum can be determined and, knowing its orientation on the reconstructed pelvis, the positions of pressure transducers within the instrumented femoral prosthesis can be found on the cartilage. Thus, given in-vivo kinematic data for our subject, it is possible to know where the measured pressures were acting within the acetabulum during various activities. Previous work (Carlson. 1993) has relied on data from the literature to orient the acetabulum.