A novel navigation system for computer assisted orthopaedic surgery

Arthroscopy is routinely used as a surgical treatment for several joint disorders. Its moderate invasiveness ensures minor tissue damage and faster post-surgical recovery. Arthroscopic surgical procedures require, however, considerable dexterity and skill due to the limited 2D view of the scene and restricted operating area. The target of this novel system for computer assisted arthroscopic surgery is to help the surgeon overcome these limitations by providing an augmented reality environment. The key feature of the system is an interactive graphical interface in which a 3D model and two 2D projections (frontal and sagittal) of the patient´s joint are shown together with a model of the arthroscope and of other sensorized surgical instruments. Sensors are also fastened to the patient´s anatomy. The positions of the sensorized objects are tracked in real-time by an optoelectronic localizer and displayed in the virtual scene. The field of view of the arthroscope is also dynamically highlighted on the model. The 3D model of the joint is reconstructed from a preoperative CT/MRI data set. The virtual model and the actual anatomy are matched by means of an ICP-based non-fiducial registration algorithm. The prototype system has been positively evaluated by a selected group of qualified orthopaedic surgeons. Preliminary tests on the overall accuracy of the system show that errors can be kept within 3°/3 mm and negotiation over the industrial exploitation of the prototype is currently in progress