ABSTRACT
Femoral screw-plate Osteosynthesis is a surgical procedure that stabilizes and joins the ends of fractured femur bones (head or neck) by implants such as metal plates, pins or screws. In this paper, we deal with the screw trajectory estimation. In fact, we focus on position, direction and length estimation of the nail in order to avoid possible complications such as screw femoral neck effraction or screw articular penetration. These complications are due to measures calculated on antero posterior and lateral views. In our approach we propose to estimate implant trajectory from 3D femur patient shape rather than radiographies. This patient 3D shape was computed from the two orthogonal views and a statistical 3D model representing the population. At first, a 3D segmentation of the femur is carried out. We propose an interactive segmentation method which consists in positioning cut planes that separates the neck from the head of the femur. The choice of these cut planes requires a physician expert to perform a better extraction of the desired zones. Then, a safety zone for each segmentedregion is determined. The implant must be inside these zones to avoid complications. The safety zone of the femoral head is defined as the inscribed sphere in this head whereas the safety zone of the femoral neck is defined as the inscribed cylinder in this neck [2], In order to control the position of the implant inside the femur, collision detection method is used. This method allows generating characteristics of the collision between the femur and the implant. These characteristics correspond to the suitable implant position, length and direction.
