A development of navigation system for mosaic plasty using electromagnetic sensor

Mosaic plasty is a surgery that transplant osteochondral grafts for osteochondritis dissecans. In mosaic plasty, cylindrical osteochondral grafts are harvested from normal area, and transplanted to injured area. The one of the most important thing of this surgery is that the graft should be perpendicular to the surface of the cartilage. The navigation system that aims improvement of precision is already studied, however cannot be applied to use an endoscope. In addition, it is a problem to have bad precision of the transplant in the freehand. Therefore, we thought that the system would widely used if we develop the mosaic plasty navigation system under an endoscope. This study proposes a navigation system to determine a proper position and pose for harvesting. In the experiments, a femoral imitation bone is used as a profile of the femoral joint surface. The experiment consists of the following three procedures: Trace and display of the femoral joint surface profile and a harvester. Display of a normal vector for the femoral joint surface. Measurement of the deviation of the normal vector. In the results, the developed system could display the femoral joint surface and the normal vector for the femoral joint surface virtually. Also, the deviation of the normal vector was an average of 7.27 degrees. As future works, there are to decrease the deviation of the normal vector by improving the precision to acquire the femoral joint surface profile, and to visualize the normal vector for the generated surface.