A development of surgery instrument pose support system for mosaicplasty by using force distribution

Mosaicplasty is one of the surgeries for knee cartilage injury. It transplants the bone autograft with the cartilage to the injured area. In this surgery, it is important to harvest the cartilage graft vertically and transplant it vertically by using a harvester for preventing area around transplant from discontinuous of the cartilage surface. This study set the goal to develop a system to estimate the pose of harvester against the articular surface in considering with a force distribution measured by a force sensor. The proposal method measures a force distribution on the cartilage surface by using force sensors which is attached to the frontal edge of a holder instrument that keeps a proper direction of the harvestor. The force distribution can enable us to estimate the positional relationship between the articular surface and harvester. The experiment used a portable force tester for loading, and estimated the angle of the harvester. The result shows the maximum of the angle estimation error was 8 degrees. The experiment of angle estimation performed multiple times, it was confirmed reproducibility. This accuracy is sufficient for practical situation, because a study reported that the error of free-hand is about 10 degree. A future work is to apply this system to the cadaveric body.