Radiograph Based Patient-Specific Customization of a Generic Femur

Three dimensional (3D) visualization of anatomy plays an important role in image guided orthopedic surgery and ultimately motivates minimally invasive procedures. However, direct 3D imaging modalities such as computed tomography (CT) are restricted to a minority of complex orthopedic procedures. Thus the diagnostics and planning of many interventions still rely on two dimensional (2D) radiographic images, where the surgeon has to mentally visualizing the anatomy of interest. Therefore, a crucial enhancement to the current orthopedic imaging practice would be to facilitate pre and intra-operatively 3D visualization by providing a compelling alternative to direct 3D imaging modalities. This paper presents a new concept for the pre-operative reconstruction of intact 3D bony anatomy and is proposed as a substitute to CT scanning for certain procedures. The human femur has been used as the anatomy of interest throughout the paper. The proposed methodology is based on two conventional orthogonal (anterior and lateral) 2D radiographic images and a supporting database of 3D intact anatomical surface models. Firstly, a search over the database finds the closest match to the patient´s bone. The best matched healthy bone is then customized through a non-rigid registration to match the shape of the patient-specific anatomy. It is this shape customization that is the focus of the paper. This process is used as the precursor to reconstruct a fractured bone model to be used intra-operatively for pose estimation (tracking).