Haptics with Applications to Cranio-Maxillofacial Surgery Planning

Virtual surgery planning systems have demonstrated great potential to help surgeons achieve a better functional and aesthetic outcome for the patient, and at the same time reduce time in the operating room resulting in considerable cost savings. However, the two-dimensional tools employed in these systems today, such as a mouse and a conventional graphical display, are difficult to use for interaction with three-dimensional anatomical images. Therefore surgeons often outsource virtual planning which increases cost and lead time to surgery. Haptics relates to the sense of touch and haptic technology encompasses algorithms, software, and hardware designed to engage the sense of touch. To demonstrate how haptic technology in combination with stereo visualization can make cranio-maxillofacial surgery planning more efficient and easier to use, we describe our haptics-assisted surgery planning (HASP) system. HASP supports in-house virtual planning of reconstructions in complex trauma cases, and reconstructions with a fibula osteocutaneous free flap including bone, vessels, and soft-tissue in oncology cases. An integrated stable six degrees-of-freedom haptic attraction force model, snap-to-fit , supports semi-automatic alignment of virtual bone fragments in trauma cases. HASP has potential beyond this thesis as a teaching tool and also as a development platform for future research. In addition to HASP, we describe a surgical bone saw simulator with a novel hybrid haptic interface that combines kinesthetic and vibrotactile feedback to display both low frequency contact forces and realistic high frequency vibrations when a virtual saw blade comes in contact with a virtual bone model. We also show that visuo-haptic co-location shortens the completion time, but does not improve the accuracy, in interaction tasks performed on two different visuo-haptic displays: one based on a holographic optical element and one based on a half-transparent mirror. Finally, we describe two prototype hand-worn haptic interfaces that potentially may expand the interaction capabilities of the HASP system. In particular we evaluate two different types of piezo-electric motors, one walking quasi-static motor and one traveling-wave ultrasonic motor for actuating the interfaces.