Voxel-based haptic training simulator for screw insertion in knee osteotomy

Knee osteotomy is a common surgery to realign the knee damaged on one side by arthritis. The procedure often requires the insertion of a screw implant into the patient´s tibia. An experienced surgeon develops a tactile sensation to prevent screw stripping and to achieve the most favorable tightness between the bone and the screw. A haptic simulator has been designed and implemented as a training platform for novice surgeons, helping them to develop this particular sensation by practicing the procedure in a virtual environment. Patient-specific CT images were used to construct an anatomically accurate knee model. A voxel-based algorithm was developed to compute the torque response based on the property of bone tissues and the geometry of the screw. A torque feedback device was also designed and used to control the virtual screw and output proper torque resistance to the user. Evaluation of the simulator showed that the resistance torques during the insertion, tightening and stripping phase of screw insertion was effectively simulated.