Intra-operative 3D pose estimation of fractured bone segments for image guided orthopedic surgery

The widespread adoption of minimally invasive surgical techniques have driven the need for 3D intra-operative image guidance. Hence the 3D pose estimation (position and orientation) performed through the registration of pre-operatively prepared 3D anatomical data to intra-operative 2D fluoroscopy images is one of the main research areas of image guided orthopedic surgery. The goal of this 2D-3D registration is to fuse highly detailed 3D information with the 2D images acquired intra-operatively to provide a real-time 3D visualization of the patient´s anatomy during surgery. Existing research work on fractured bone pose estimation focuses on tracking pre-operatively obtained 3D CT data through fiduciary markers implanted intra-operatively. This expensive and invasive approach is not routinely available for diagnostics, and a majority of fracture reduction procedures solely relies on xray/fluoroscopic images. The proposed concept eliminates the need to have the pre-operative CT scan of the patient´s injured anatomy and presents a non-invasive anatomy-based method for intra-operative pose estimation. The concept pre-operatively reconstructs a patient-specific fractured bone model utilizing two conventional x-ray images orthogonally (in anterior and lateral views) and a generic healthy 3D anatomical model. This pre-operatively reconstructed 3D model will then be utilized intra-operatively in the novel 2D-3D registration process for pose estimation. It is this registration process that is the focus of this paper. The registration is performed solely utilizing bony anatomical features extracted from fluoroscopic images without invasiveness external fiducial markers.