Force and Torque Modeling for the Drilling of Bone for use in Orthopaedic Haptic Simulation Systems

The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with a tool for training and preoperative planning. This is especially true for procedures involving the drilling of bone which requires a great amount of adroitness and experience. One of the potential difficulties with the drilling of bone is the lack of consistent material evacuation from the drill’s flutes as the material tends to clog. This clogging leads to significant increases in force and torque experienced by the surgeon which has not been appropriately addressed by current simulation systems. This thesis proposes several force and torque prediction models that account for this phenomenon. Each of the models was calibrated via experimentation and their accuracy was substantiated through an experimental validation process. As an example of the application of the models, a finite element simulation investigating the effect of drilling forces and moments on the dynamic response of a femur bone was studied.

Force and Torque Modeling for the Drilling of Bone for use in Orthopaedic Haptic Simulation Systems

The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with a tool for training and preoperative planning. This is especially true for procedures involving the drilling of bone which requires a great amount of adroitness and experience. One of the potential difficulties with the drilling of bone is the lack of consistent material evacuation from the drill’s flutes as the material tends to clog. This clogging leads to significant increases in force and torque experienced by the surgeon which has not been appropriately addressed by current simulation systems. This thesis proposes several force and torque prediction models that account for this phenomenon. Each of the models was calibrated via experimentation and their accuracy was substantiated through an experimental validation process. As an example of the application of the models, a finite element simulation investigating the effect of drilling forces and moments on the dynamic response of a femur bone was studied.

Force quantification and simulation of pedicle screw tract palpation using direct visuo-haptic volume rendering

Purpose We present a feasibility study for the visuo-haptic simulation of pedicle screw tract palpation in virtual reality, using an approach that requires no manual processing or segmentation of the volumetric medical data set. Methods In a first experiment, we quantified the forces and torques present during the palpation of a pedicle screw tract in a real boar vertebra. We equipped a ball-tipped pedicle probe with a 6-axis force/torque sensor and a motion capture marker cluster. We simultaneously recorded the pose of the probe relative to the vertebra and measured the generated forces and torques during palpation. This allowed us replaying the recorded palpation movements in our simulator and to fine-tune the haptic rendering to approximate the measured forces and torques. In a second experiment, we asked two neurosurgeons to palpate a virtual version of the same vertebra in our simulator, while we logged the forces and torques sent to the haptic device. Results In the experiments with the real vertebra, the maximum measured force along the longitudinal axis of the probe was 7.78 N and the maximum measured bending torque was 0.13 Nm. In an offline simulation of the motion of the pedicle probe recorded during the palpation of a real pedicle screw tract, our approach generated forces and torques that were similar in magnitude and progression to the measured ones. When surgeons tested our simulator, the distributions of the computed forces and torques were similar to the measured ones; however, higher forces and torques occurred more frequently. Conclusions We demonstrated the suitability of direct visual and haptic volume rendering to simulate a specific surgical procedure. Our approach of fine-tuning the simulation by measuring the forces and torques that are prevalent while palpating a real vertebra produced promising results.

Using Game Engines for Visuo-Haptic Learning Simulations

Technological advances have been the main driver of enhancing human–computer interaction and interactive simulations have experienced exponential growth in recent years. However, visual and auditory channels are usually the only ones considered for educational simulations even though the sense of touch is also an important one. Touch allows us to recognize and interact with our surroundings. A common way to develop a visuo-haptic simulation in the area of interactive systems is by using a graphic and physics-based engine orchestrated with a haptic rendering framework. However, new solutions, such as professional game engines, have enabled the development of high-quality applications in much shorter time. In this paper, a novel architecture for fast development of interactive visuo-haptic applications in game engines is discussed. To validate the proposed architecture, the Haptic Device Integration for Unity (HaDIU) plugin was implemented. Simulations were implemented to verify the operability of haptic devices. Each scenario was properly modelled and has different haptic objectives. Furthermore, to validate that the usage of this approach provides better visualizations than an existing single purpose application, an experimental study was performed. Results suggest that by using this approach faster development of interactive visuo-haptic simulators can be achieved than using traditional techniques.

Investigating the construct validity of a haptic virtual caries simulation for dental education

IntroductionTeaching dental caries removal is limited by the material and methods available in the preclinical teaching space. Plastic teeth do not simulate the tactile feel of a lesion and natural teeth do not allow for standardised training and assessment. A novel method for simulating caries has been reported. Here, to investigate the construct validity of a caries simulation, whether haptic simulation could contribute to the understanding of caries removal, the performance of first-year dental students on the haptic simulation exercise is compared with that of experienced dentists.MethodA virtual block comprising healthy dentine, pulp, enamel and a carious lesion with significant spread along the amelodentinal junction (ADJ) was developed for the Simodont dental trainer. The case was presented to 112 first-year students and 17 clinicians following a 15 min training period on a block which contained green caries and displayed live progress throughout the exercise. All participants were given the same verbal instructions: to remove all unsupported enamel and caries along the ADJ while retaining as much healthy tissue as possible.ResultsClinicians performed better than the dental novices in precision and overall performance. Clinicians removed more material on average, except for healthy dentine, of which similar amounts were removed by both groups.DiscussionWe presented a novel haptic caries exercise and investigated the construct validity of the task. The simulation may bridge the gap between preclinical and clinical dental education in caries removal.ConclusionClinically experienced dentists outperformed novices on a haptic caries simulation exercise. The exercise may be a useful tool for assessing conceptual understanding of caries removal.