Research On Digital Geometry Processing For Navigation Surgery In Orthopaedics And Its Application

As the world entered a high degree of aging of the era, the bone and joint diseases of elderly people are becoming more and more serious. The artificial joint replacement is one of the standard treatment methods for joint disease after its development for more than a century. It can relieve pain, improve the joint function and restore the stability of the joint. However, because of the limited viewing area, the surgeons achieve relative position and orientation information on implants, surgical tools and patient relying on the repeated X-ray in the traditional conditions. This not only requires experienced surgeons, but also increases X-ray radiation for surgeons and patients, extends the operation time, and increase the risk of infection. Moreover, because the surgeons could not real-time monitor the operation process, the final surgery quality could not be controlled. Aiming at solving these problems, the digital geometry processing for navigation surgery in orthopaedics and its application is studied in this paper. The Total Knee Replacement System (TKR) and the Femoral Head Resurfacing System (FHR) are developed and the registration function in navigation surgery for avascular necrosis of femoral head is realized. The main contents are as follows.1. The point clouds data are acquired by Polaris optical tracking system and be unified in the same coordinate system by the rotation matrix represented by quaternion. The outlier is removed by the minimum spanning tree clustering algorithm to ensure the model quality reconstructed. This acquisition and pretreatment methods for point cloud data are applied in the Femoral Head Resurfacing System.2. Fitting points clouds data to geometric primitives by the least squares method is used in model reconstruction. This method is applied in the Femoral Head Resurfacing System.3. Based on the review of literatures, the medical image registration methods are classified. The rigid body registration algorithms using geometric features including point-based registration and surface-based registration are studied in detail according to the features of surgery navigation system in orthopaedics. To avoid the partial minimum problem in ICP algorithm, a good initial estimate is provided based on multi-level strategy. The speed and accuracy of ICP algorithm are improved by this method.4. The applications of point cloud processing, surface fitting and other related digital geometry processing methods in image-free navigation surgery system, such as the total knee replacement and the femoral head resurfacing, are introduced in detail in this paper. The application of point-surface-based registration in image guide navigation surgery system, such as surgery for avascular necrosis of femoral head is also introduced in detail. The precision and performance tests of these various systems are performed by model experiment or body experiment.Since computer assisted surgery technologies are attracting more and more attention. I think our research work will be benefit for intellectual property rights autonomy of our country in the field of computer assisted surgery.