A development of navigation system with image segmentation in mosaicplasty of the knee

Mosaicplasty is a surgery that transplants osteochondral grafts for osteochondritis dissecans. In mosaicplasty, cylindrical osteochondral grafts are harvested from normal area, and transplanted to injured area. The one of the most important things of this surgery is that the graft should be perpendicular to the surface of the cartilage. The navigation system that aims improvement of precision has been already studied, however cannot be applied to use an endoscope. In addition, it is a problem to have low precision of the transplant in the freehand. Therefore, we thought that the system would be widely used if we develop the mosaicplasty 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 was used as a profile of the femoral joint surface. The experiment consists of the following three procedures: Scan and display of the femoral joint surface profile. Display of a normal vector for the femoral joint surface and a harvester. Measurement of the accuracy 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 angle between the surface normal vector and the real normal vector was an average of 6.50 degree. As a future work, the stereographic system using camera should be downsized.