Bone drilling haptic interaction for orthopedic surgical simulator

Fast and precise collision detection for detailed and complex physiological structures

BACKGROUND AND OBJECTIVES

Virtual reality has been proved indispensable in computer-assisted surgery, especially for surgical planning, and simulation systems. Collision detection is an essential part of surgery simulators and its accuracy and computational efficiency play a decisive role in the fidelity of simulations. Nevertheless, current collision detection methods in surgical simulation and planning struggle to meet precise requirements, especially for detailed and complex physiological structures. To address this, the primary objective of this study was to develop a new algorithm that enables fast and precise collision detection to facilitate the improvement of the realism of virtual reality surgical procedures.

METHODS

The method consists of two main parts, bounding spheres formation and two-level collision detection. A specified surface subdivision method is devised to reduce the radius of basic bounding spheres formed by circumcenters of underlying triangles. The spheres are then clustered and adjusted to obtain a compact personalized hierarchy whose position is updated in real time during surgical simulation, followed by two-level collision detection. Triangular facets with collision potential through interaction between hierarchies and then accurate results are obtained by means of precise detection phase. The effectiveness of the algorithm was evaluated in various models and surgical scenarios and was compared with prior relevant implementations.

RESULTS

Results on multiple models demonstrated that the method can generate a personalized hierarchy with fewer and smaller bounding spheres for tight wrapping. Simulation experiments proved that the proposed approach is significantly superior to comparable methods under the premise of error-free detection, even for severe model-model collision.

CONCLUSIONS

The algorithm proposed through this study enables higher numerical efficiency and detection accuracy, which is capable of significantly enlarging the fidelity/realism of haptic simulators and surgical planning methods.

Cutting-Force Modeling Study on Vibration-Assisted Micro-Milling of Bone Materials

This study aims to enhance surgical safety and facilitate patient recovery through the investigation of vibration-assisted micro-milling technology for bone-material removal. The primary objective is to reduce cutting force and improve surface quality. Initially, a predictive model is developed to estimate the cutting force during two-dimensional (2D) vibration-assisted micro-milling of bone material. This model takes into account the anisotropic structural characteristics of bone material and the kinematics of the milling tool. Subsequently, an experimental platform is established to validate the accuracy of the cutting-force model for bone material. Micro-milling experiments are conducted on bone materials, with variations in cutting direction, amplitude, and frequency, to assess their impact on cutting force. The experimental results demonstrate that selecting appropriate machining parameters can effectively minimize cutting force in 2D vibration-assisted micro-milling of bone materials. The insights gained from this study provide valuable guidance for determining cutting parameters in vibration-assisted micro-milling of bone materials.

Application of Virtual Reality Systems in Bone Trauma Procedures

Background and Objectives: Bone fractures contribute significantly to the global disease and disability burden and are associated with a high and escalating incidence and tremendous economic consequences. The increasingly challenging climate of orthopaedic training and practice re-echoes the established potential of leveraging computer-based reality technologies to support patient-specific simulations for procedural teaching and surgical precision. Unfortunately, despite the recognised potential of virtual reality technologies in orthopaedic surgery, its adoption and integration, particularly in fracture procedures, have lagged behind other surgical specialities. We aimed to review the available virtual reality systems adapted for orthopaedic trauma procedures. Materials and Methods: We performed an extensive literature search in Medline (PubMed), Science Direct, SpringerLink, and Google Scholar and presented a narrative synthesis of the state of the art on virtual reality systems for bone trauma procedures. Results: We categorised existing simulation modalities into those for fracture fixation techniques, drilling procedures, and prosthetic design and implantation and described the important technical features, as well as their clinical validity and applications. Conclusions: Over the past decade, an increasing number of high- and low-fidelity virtual reality systems for bone trauma procedures have been introduced, demonstrating important benefits with regard to improving procedural teaching and learning, preoperative planning and rehearsal, intraoperative precision and efficiency, and postoperative outcomes. However, further technical developments in line with industry benchmarks and metrics are needed in addition to more standardised and rigorous clinical validation.

Application of Virtual and Augmented Reality Technology in Hip Surgery: Systematic Review

BACKGROUND

Virtual and augmented reality (VAR) represents a combination of current state-of-the-art computer and imaging technologies and has the potential to be a revolutionary technology in many surgical fields. An increasing number of investigators have developed and applied VAR in hip-related surgery with the aim of using this technology to reduce hip surgery-related complications, improve surgical success rates, and reduce surgical risks. These technologies are beginning to be widely used in hip-related preoperative operation simulation and training, intraoperative navigation tools in the operating room, and postoperative rehabilitation.

OBJECTIVE

With the aim of reviewing the current status of virtual reality (VR) and augmented reality (AR) in hip-related surgery and summarizing its benefits, we discussed and briefly described the applicability, advantages, limitations, and future perspectives of VR and AR techniques in hip-related surgery, such as preoperative operation simulation and training; explored the possible future applications of AR in the operating room; and discussed the bright prospects of VR and AR technologies in postoperative rehabilitation after hip surgery.

METHODS

We searched the PubMed and Web of Science databases using the following key search terms: ("virtual reality" OR "augmented reality") AND ("pelvis" OR "hip"). The literature on basic and clinical research related to the aforementioned key search terms, that is, studies evaluating the key factors, challenges, or problems of using of VAR technology in hip-related surgery, was collected.

RESULTS

A total of 40 studies and reports were included and classified into the following categories: total hip arthroplasty, hip resurfacing, femoral neck fracture, pelvic fracture, acetabular fracture, tumor, arthroscopy, and postoperative rehabilitation. Quality assessment could be performed in 30 studies. Among the clinical studies, there were 16 case series with an average score of 89 out of 100 points (89%) and 1 case report that scored 81 (SD 10.11) out of 100 points (81%) according to the Joanna Briggs Institute Critical Appraisal Checklist. Two cadaveric studies scored 85 of 100 points (85%) and 92 of 100 points (92%) according to the Quality Appraisal for Cadaveric Studies scale.

CONCLUSIONS

VR and AR technologies hold great promise for hip-related surgeries, especially for preoperative operation simulation and training, feasibility applications in the operating room, and postoperative rehabilitation, and have the potential to assist orthopedic surgeons in operating more accurately and safely. More comparative studies are necessary, including studies focusing on clinical outcomes and cost-effectiveness.

Computational evaluation of the axis-blade angle for measurements of implant positions in trochanteric hip fractures: A finite element analysis

BACKGROUND

Recently, a novel approach axis-blade angle (ABA) was developed to measure implant positions during trochanteric hip fracture surgery. It was defined as the sum of two angles α and β measured between the femoral neck axis and helical blade axis in anteroposterior and lateral X-ray films, respectively. Although its clinical practicability has been confirmed, the mechanism is yet to be investigated by means of finite element (FE) analysis.

METHODS

Computed tomography images of four femurs and dimensions of one implant at three angles were obtained to construct FE models. For each femur, 15 FE models in an arrangement (intramedullary nails at three angles multiplying five blade positions) were established. Under the simulation of normal walking loads, the ABA, von Mises stress (VMS), maximum/minimum principal strain and displacement were analyzed.

RESULTS

When the ABA increased, all outcome indicators initially decreased till reaching inferior-middle site and then increased while the blade positions within the femoral head shifted from the superior-anterior quadrant toward the inferior-posterior quadrant, where the ABA were higher. Only the peak VMS of implant models in the inferior-posterior quadrant (particularly the inferior-middle site within) with blades in did not reach the yielding (risky) cut-off.

CONCLUSIONS

From the perspective of angles, ABA, this study demonstrated the inferior-posterior quadrant as the relatively stable and safe regions, especially the inferior-middle site within. This was similar but more elaborate compared with previous studies and clinical practice. Therefore, ABA could be employed as a promising approach to anchor the implants into the optimal region.

An objective assessment for bone drilling: A pilot study on vertical drilling

The purpose of this study is to propose a quantitative assessment scheme to help with surgical bone drilling training. This pilot study gathered and compared motion and force data from expert surgeons (n = 3) and novice residents (n = 6). The experiment used three-dimensional printed bone simulants of young bone (YB) and osteoporotic bone (OB), and drilling overshoot, time, and force were measured. There was no statistically significant difference in overshoot between the two groups (p = 0.217 for YB and 0.215 for OB). The results, however, show that the experts took less time (mean = 4.01 s) than the novices (mean = 9.98 s), with a statistical difference (p = 0.003 for YB and 0.0001 for OB). In addition, the expert group performed more consistently than the novices. The force analysis further revealed that experts used a higher force to drill the first cortical section and a noticeably lower force in the second cortex to control the overshoot (approximate reduction of 5.5 N). Finally, when drilling time and overshoot distance were combined, the motion data distinguished the skill gap between expert and novice drilling; the force data provided insight into the drilling mechanism and performance outcomes. This study lays the groundwork for a data-driven training scheme to prepare novice residents for clinical practice.

Virtual Reality in Orthopedic Surgery Training

One emerging technology with the potential to improve and further transform the field of orthopaedic surgery is virtual reality (VR). VR has been explored and used in many different specialties with clinical applications, such as psychiatric therapy, pain management, rehabilitation, and traumatic brain injury. Recent studies have suggested that the use of VR during the training of orthopaedic surgery residents produces similar or improved surgical performance by residents. This is an area where VR can provide a tremendous benefit to the field of orthopaedic surgery, as it offers a safe and accessible complement to orthopaedic surgical training outside of the operating room (OR) and without involving patients directly. This review will elucidate the current state of virtual reality use in the training of orthopaedic surgeons and highlight key benefits and challenges in its application as a training resource.

A virtual reality simulator for training the surgical reduction of patient-specific supracondylar humerus fractures

PURPOSE

Virtual reality has been used as a training platform in medicine, allowing the repetition of a situation/scenario as many times as needed and making it patient-specific prior to an operation. Of special interest is the minimally invasive plate osteosynthesis (MIPO). It represents a novel technique for orthopedic trauma surgery, but requires intensive training to acquire the required skills. In this paper, we propose a virtual reality platform for training the surgical reduction of supracondylar fractures of the humerus using MIPO. The system presents a detailed surgical theater where the surgeon has to place the bone fragments properly.

METHODS

Seven experienced users were selected to perform a surgical reduction using our proposal. Two paired humeri were scanned from a dataset obtained from the Complejo Hospitalario de Jaén. A virtual fracture was performed in one side of the pair, using the other as contralateral part. Users have to simulate a reduction for each case and fill out a survey about usability, using a five-option Likert scale.

RESULTS

The subjects have obtained excellent scores in both simulations. The users have notably reduced the time employed in the second experiment, being 60% less in average. Subjects have valued the usability (5.0), the intuitiveness (4.6), comfort (4.5), and realism (4.9) in a 1-5 Likert scale. The mean score of the usability survey was 4.66.

CONCLUSION

The system has shown a high learning rate, and it is expected that the trainees will reach an expert level after additional runs. By focusing on the movement of bone fragments, specialists acquire motor skills to avoid the malrotation of MIPO-treated fractures. A future study can fulfill the requirements needed to include this training system into the protocol of real surgeries. Therefore, we expect the system to increase the confidence of the trainees as well as to improve their decision making.

Comparative Analysis of Cutting Forces, Torques, and Vibration in Drilling of Bovine, Porcine, and Artificial Femur Bone with Considerations for Robot Effector Stiffness

Bone drilling is known as one of the most sensitive milling processes in biomedical engineering field. Fracture behavior of this cortical bone during drilling has attracted the attention of many researchers; however, there are still impending concerns such as necrosis, tool breakage, and microcracks due to high cutting forces, torques, and high vibration while drilling. This paper presents a comparative analysis of the cutting forces, torques, and vibration resulted on different bone samples (bovine, porcine, and artificial femur) using a 6dof Robot arm effector with considerations of its stiffness effects. Experiments were conducted on two spindle speeds of 1000 and 1500 rpm with a drill bit diameter of 2.5 mm and 6 mm depth of cut. The results obtained from the specimens were processed and analyzed using MATLAB R2015b and Visio 2000 software; these results were then compared with a prior test using manual and conventional drilling methods. The results obtained show that there is a significant drop in the average values of maximum drilling force for all the bone specimens when the spindle speed changes from 1000 rev/min to 1500 rev/min, with a drop from (20.07 to 12.34 N), approximately 23.85% for bovine, (11.25 to 8.14 N) with 16.03% for porcine, and (5.62 to 3.86 N) with 33.99% for artificial femur. The maximum average values of torque also decrease from 41.2 to 24.2 N·mm (bovine), 37.0 to 21.6 N·mm (porcine), and 13.6 to 6.7 N·mm (artificial femur), respectively. At an increase in the spindle speed, the vibration amplitude on all the bone samples also increases considerably. The variation in drilling force, torque, and vibration in our result also confirm that the stiffness of the robot effector joint has negative effect on the bone precision during drilling process.

Design and Characterization of an Actuated Drill Mockup for Orthopedic Surgical Training

Haptic feedback in virtual reality-based trainers for surgical bone drilling is mostly provided via impedance-controlled haptic devices. Due to this, the displayable maximum stiffness is limited. In addition, vibration feedback is often only of reduced fidelity. To overcome these shortcomings, we have developed a hand-held, actuated admittance-controlled drill mockup, comprising enhanced kinesthetic and tactile feedback. This article reports on design and characterization of the device, and highlights its use for training. Kinesthetic feedback is provided through haptic augmentation, employing a ball-screw mechanism acting on a retractable drill-bit. Feedback computation relies on admittance control, thus allowing for stable display of very high resistance forces, and thus material stiffness, which cannot be achieved with standard impedance-control approaches. For the tactile mechanism, a modified linear vibration actuator is directly attached to the mockup handle, improving signal transmission. Tactile feedback computation is based on an extension of a previously proposed power spectral density control method. Frequency-specific gains are adjusted in real-time, compensating for differences between desired and measured vibrations. The performance of the device is characterized in several experiments, including comparisons to drilling with a real drill into artificial bone samples. In addition, several user studies have been carried out. We illustrate the capability of the mockup to render bone samples with different material layer stiffness and thickness. Moreover, we show that the mockup system allows for the same training effect as when rehearsing with a real drill.

A review of computer-assisted orthopaedic surgery systems

BACKGROUND

Computer-assisted orthopaedic surgery systems have great potential, but no review has focused on computer-assisted surgery systems for the spine, hip, and knee.

METHODS

A systematic search was performed in Web of Science and PubMed. We searched the literature on computer-assisted orthopaedic surgery systems from 2008 to the present and focused on three aspects of systems: training, planning, and intraoperative navigation.

RESULTS AND DISCUSSION

In this review study, we reviewed 34 surgical training systems, 31 surgical planning systems, and 41 surgical navigation systems. The functions and characteristics of the surgical systems were compared and analysed, and the current concerns about and the impact of the surgical systems on doctors and surgery were clarified.

CONCLUSION

Computer-assisted orthopaedic surgery systems are still in the development stage. Future surgical training systems should include synthetic models with patient anatomy. Surgical planning systems with automatic planning should be developed, and surgical navigation systems with multimodal fusion, robotic assistance and imaging should be developed.

The role of virtual and augmented reality in orthopedic trauma surgery: From diagnosis to rehabilitation

Virtual and augmented reality have been used to assist and improve human capabilities in many fields. Most recent advances allow the usage of these technologies for personal and professional purposes. In particular, they have been progressively introduced in many medical procedures since the last century. Thanks to immersive training systems and a better comprehension of the ongoing procedure, their main objectives are to increase patient safety and decrease recovery time. The current and future possibilities of virtual and augmented reality in the context of bone fracture reduction are the main focus of this review. This medical procedure requires meticulous planning and a complex intervention in many cases, hence becoming a promising candidate to be benefited from this kind of technology. In this paper, we exhaustively analyze the impact of virtual and augmented reality to bone fracture healing, detailing each task from diagnosis to rehabilitation. Our primary goal is to introduce novel researchers to current trends applied to orthopedic trauma surgery, proposing new lines of research. To that end, we propose and evaluate a set of qualitative metrics to highlight the most promising challenges of virtual and augmented reality technologies in this context.

Parallelized collision detection with applications in virtual bone machining

BACKGROUND AND OBJECTIVES

Virtual reality surgery simulators have been proved effective for training in several surgical disciplines. Nevertheless, this technology is presently underutilized in orthopaedics, especially for bone machining procedures, due to the limited realism in haptic simulation of bone interactions. Collision detection is an integral part of surgery simulators and its accuracy and computational efficiency play a determinant role on the fidelity of simulations. To address this, the primary objective of this study was to develop a new algorithm that enables faster and more accurate collision detection within 1 ms (required for stable haptic rendering) in order to facilitate the improvement of the realism of virtual bone machining procedures.

METHODS

The core of the developed algorithm is constituted by voxmap point shell method according to which tool and osseous tissue geometries were sampled by points and voxels, respectively. The algorithm projects tool sampling points into the voxmap coordinates and compute an intersection condition for each point-voxel pair. This step is massively parallelized using Graphical Processing Units and it is further accelerated by an early culling of the unnecessary threads as instructed by the rapid estimation of the possible intersection volume. A contiguous array was used for implicit definition of voxmap in order to guarantee a fast access to voxels and thereby enable efficient material removal. A sparse representation of tool points was employed for efficient memory reductions. The effectiveness of the algorithm was evaluated at various bone sampling resolutions and was compared with prior relevant implementations.

RESULTS

The results obtained with an average hardware configuration have indicated that the developed algorithm is capable to reliably maintain < 1 ms running time in severe tool-bone collisions, both sampled at 1024³ resolutions. The results also showed the algorithm running time has a low sensitivity to bone sampling resolution. The comparisons performed suggested that the proposed approach is significantly faster than comparable methods while relying on lower or similar memory requirements.

CONCLUSIONS

The algorithm proposed through this study enables a higher numerical efficiency and is capable to significantly enlarge the maximum resolution that can be used by high fidelity/high realism haptic simulators targeting surgical orthopaedic procedures.

Comprehensive analysis on orthopedic drilling: A state-of-the-art review

Bone drilling is a well-known internal fixation procedure to drill a hole, fixing the bone fragments to reduce the susceptibility of permanent paralysis. The success of bone drilling is evaluated based on the extent of osteonecrosis in terms of heat generation, tissue damage, quality of hole, and drilling forces. The appropriate control of cutting conditions, drill geometric parameters, and bone-specific parameters offer bone drilling a viable solution through conventional and non-conventional drilling techniques. The majority of the published research work considers only limited parameters and tries to optimize the drilling parameters and performance measures. However, bone drilling involves numerous conventional and non-conventional drilling parameters and technologies. In order to develop a better understanding of all the studied parameters and performance measures, there is a dire need to develop a framework. The key objective of this review study is to establish a hierarchy of the framework by collecting almost all the parameters studied until now and addressed the relationship between parameters and performance measures to diminish the controversies in the published literature. Therefore, this framework is novel in nature, organizing all the parameters, performance measures, logical comparisons, and limitations of studies. This holistic review can help medical surgeons and design engineers to understand the complicated relationship among parameters and performance measures associated with this state-of-art technologies. Also, modeling, simulations, and optimization techniques are included to explore the application of such techniques in recent advancements in orthopedic drilling.

MULTI-OBJECTIVE OPTIMIZATION FOR SURGICAL DRILLING OF HUMAN FEMURS: A METHODOLOGY FOR BETTER PULL-OUT STRENGTH OF FIXATION USING TAGUCHI METHOD BASED ON MEMBERSHIP FUNCTION

Drilling through bone is one of the common cutting processes involved in many of the orthopedic surgeries. In bone drilling, spindle speed, feed rate, diameter of the drill bit, drill bit geometry and method of cooling are the important parameters to influence the in-situ temperature, drill thrust force and quality characteristics of the drilled hole. Because of the selection of inappropriate drilling parameters, uncontrolled large drilling forces, continuous increase in temperature and mechanical damage to the local host bone were observed. As these adverse effects lead to poor bone–implant contact and often a revision surgery, performing a surgical drilling with optimal parameters is essential to succeed in the surgical procedure. It was observed that in addition to the variations in apparent bone density, the orientation of osteons influences the drilling thrust force and temperature in bone drilling. Ten adult cadaveric human femurs from the age group of 32–65 years were considered and drilling experiments were conducted on proximal-diaphysis, mid-diaphysis and distal-diaphysis regions in the longitudinal, radial and circumferential directions. Bone drilling with different spindle speeds (500, 1000 and 1500[Formula: see text]rpm), feed rates (40, 60 and 80[Formula: see text]mm/min), and apparent density in the range of 0.98[Formula: see text]g/cm3 to 1.98[Formula: see text]g/cm3 was investigated in this work using a 3.20[Formula: see text]mm diameter surgical drill-bit. The generation of in-situ temperature as well as thrust force at each target location was measured using [Formula: see text]-type thermocouple and Kistler[Formula: see text] dynamometer, respectively. Taguchi method based on membership function was used to optimize the drilling process. Then the efficacy of the method in reducing the in-situ temperature and thrust force, and quality of the drilled hole in respect of anatomical region and drilling direction was investigated using pull-out strength of the bone screws. Results revealed that the optimal parameters obtained from the Taguchi method based on membership function could simultaneously minimize the temperature as well as thrust force in bone drilling. The proposed method can be adopted to minimize the temperature and thrust force, and choose the best location nearest to the defect site for strong implant fixation by using CT datasets of the patient as the only input.

Optically tracked and 3D printed haptic phantom hand for surgical training system

Background

For surgical fixation of bone fractures of the human hand, so-called Kirschner-wires (K-wires) are drilled through bone fragments. Due to the minimally invasive drilling procedures without a view of risk structures like vessels and nerves, a thorough training of young surgeons is necessary. For the development of a virtual reality (VR) based training system, a three-dimensional (3D) printed phantom hand is required. To ensure an intuitive operation, this phantom hand has to be realistic in both, its position relative to the driller as well as in its haptic features. The softest 3D printing material available on the market, however, is too hard to imitate human soft tissue. Therefore, a support-material (SUP) filled metamaterial is used to soften the raw material. Realistic haptic features are important to palpate protrusions of the bone to determine the drilling starting point and angle. An optical real-time tracking is used to transfer position and rotation to the training system.

Methods

A metamaterial already developed in previous work is further improved by use of a new unit cell. Thus, the amount of SUP within the volume can be increased and the tissue is softened further. In addition, the human anatomy is transferred to the entire hand model. A subcutaneous fat layer and penetration of air through pores into the volume simulate shiftability of skin layers. For optical tracking, a rotationally symmetrical marker attached to the phantom hand with corresponding reference marker is developed. In order to ensure trouble-free position transmission, various types of marker point applications are tested.

Results

Several cuboid and forearm sample prints lead to a final 30 centimeter long hand model. The whole haptic phantom could be printed faultless within about 17 hours. The metamaterial consisting of the new unit cell results in an increased SUP share of 4.32%. Validated by an expert surgeon study, this allows in combination with a displacement of the uppermost skin layer a good palpability of the bones. Tracking of the hand marker in dodecahedron design works trouble-free in conjunction with a reference marker attached to the worktop of the training system.

Conclusions

In this work, an optically tracked and haptically correct phantom hand was developed using dual-material 3D printing, which can be easily integrated into a surgical training system.

Force-feedback assisted and virtual fixtures based K-wire drilling simulation

One common method to fix fractures of the human hand after an accident is an osteosynthesis with Kirschner wires (K-wires) to stabilize the bone fragments. The insertion of K-wires is a delicate minimally invasive surgery, because surgeons operate almost without a sight. Since realistic training methods are time consuming, costly and insufficient, a virtual-reality (VR) based training system for the placement of K-wires was developed. As part of this, the current work deals with the real-time bone drilling simulation using a haptic force-feedback device. To simulate the drilling, we introduce a virtual fixture based force-feedback drilling approach. By decomposition of the drilling task into individual phases, each phase can be handled individually to perfectly control the drilling procedure. We report about the related finite state machine (FSM), describe the haptic feedback of each state and explain, how to avoid jerking of the haptic force-feedback during state transition. The usage of the virtual fixture approach results in a good haptic performance and a stable drilling behavior. This was confirmed by 26 expert surgeons, who evaluated the virtual drilling on the simulator and rated it as very realistic. To make the system even more convincing, we determined real drilling feed rates through experimental pig bone drilling and transferred them to our system. Due to a constant simulation thread we can guarantee a precise drilling motion. Virtual fixtures based force-feedback calculation is able to simulate force-feedback assisted bone drilling with high quality and, thus, will have a great potential in developing medical applications.

The Effect of Training, Used-Hand, and Experience on Endoscopic Surgery Skills in an Educational Computer-Based Simulation Environment (ECE) for Endoneurosurgery Training

Today, virtual simulation environments create alternative hands-on practice opportunities for surgical training. In order to increase the potential benefits of such environments, it is critical to understand the factors that influence them. This study was conducted to determine the effects of training, used-hand, and experience, as well as the interactions between these variables, on endoscopic surgery skills in an educational computer-based surgical simulation environment. A 2-hour computer-based endoneurosurgery simulation training module was developed for this study. Thirty-one novice- and intermediate-level resident surgeons from the departments of neurosurgery and ear, nose, and throat participated in this experimental study. The results suggest that a 2-hour training during a 2-month period through computer-based simulation environment improves the surgical skills of the residents in both-hand tasks, which is necessary for endoscopic surgical procedures but not in dominant hand tasks. Based on the results of this study, it can be concluded that computer-based simulation environments potentially improve surgical skills; however, the scenarios for such training modules need to consider especially the bimanual coordination of hands and should be regularly adapted to the individual skill levels and progresses.

Imitating human soft tissue on basis of a dual-material 3D print using a support-filled metamaterial to provide bimanual haptic for a hand surgery training system

Background

Currently, it is common practice to use three-dimensional (3D) printers not only for rapid prototyping in the industry, but also in the medical area to create medical applications for training inexperienced surgeons. In a clinical training simulator for minimally invasive bone drilling to fix hand fractures with Kirschner-wires (K-wires), a 3D-printed hand phantom must not only be geometrically but also haptically correct. Due to a limited view during an operation, surgeons need to perfectly localize underlying risk structures only by feeling of specific bony protrusions of the human hand.

Methods

The goal of this experiment is to imitate human soft tissue with its haptic and elasticity for a realistic hand phantom fabrication, using only a dual-material 3D printer and support-material-filled metamaterial between skin and bone. We present our workflow to generate lattice structures between hard bone and soft skin with iterative cube edge (CE) or cube face (CF) unit cells. Cuboid and finger shaped sample prints with and without inner hard bone in different lattice thickness are constructed and 3D printed.

Results

The most elastic available rubber-like material is too firm to imitate soft tissue. By reducing the amount of rubber in the inner volume through support material (SUP), objects become significantly softer. Without metamaterial, after disintegration, the SUP can be shifted through the volume and thus the body loses its original shape. Although the CE design increases the elasticity, it cannot restore the fabric form. In contrast to CE, the CF design increases not only the elasticity but also guarantees a local limitation of the SUP. Therefore, the body retains its shape and internal bones remain in its intended place. Various unit cell sizes, lattice thickening and skin thickness regulate the rubber material and SUP ratio. Test prints with higher SUP and lower rubber material percentage appear softer and vice versa. This was confirmed by an expert surgeon evaluation. Subjects adjudged pure rubber-like material as too firm and samples only filled with SUP or lattice structure in CE design as not suitable for imitating tissue. 3D-printed finger samples in CF design were rated as realistic compared to the haptic of human tissue with a good palpable bone structure.

Conclusions

We developed a new dual-material 3D print technique to imitate soft tissue of the human hand with its haptic properties. Blowy SUP is trapped within a lattice structure to soften rubber-like 3D print material, which makes it possible to reproduce a realistic replica of human hand soft tissue.

To Improve Your Surgical Drilling Skills, Make Use of Your Index Fingers

BACKGROUND

Surgery has greatly benefited from various technologic advancements over the past decades. Surgery remains, however, mostly manual labor performed by well-trained surgeons. Little research has focused on improving osseous drilling techniques. The objective of this study was to compare the accuracy and precision of different orthopaedic drilling techniques involving the use of both index fingers.

QUESTIONS/PURPOSES

(1) Does the shooting grip technique and aiming at the contralateral index finger improve accuracy and precision in drilling? (2) Is the effect of drilling technique on accuracy and precision affected by the experience level of the performer?

METHODS

This study included 36 participants from two Dutch training hospitals who were subdivided into three groups (N = 12 per group) based on their surgical experience (that is, no experience, residents, and surgeons). The participants had no further experience with drilling outside the hospital nor were there other potential confounding variables that could influence the test outcomes. Participants were instructed to drill toward a target exit point on a synthetic bone model. There were four conditions: (1) clenched grip without aiming; (2) shooting grip without aiming; (3) clenched grip with aiming at the contralateral index finger; and (4) shooting grip aiming at the contralateral index finger. Participants were only used to a clenched grip without aiming in clinical practice. Each participant had to drill five times per technique per test, and the test was repeated after 4 weeks. Accuracy was defined as the systematic error of all measurements and was calculated as the mean of the five distances between the five exit points and the target exit point, whereas precision was defined as the random error of all measurements and calculated as the SD of those five distances. Accuracy and precision were analyzed using mixed-design analyses of variance.

RESULTS

Accuracy was highest when using a clenched grip with aiming at the index finger (mean 4.0 mm, SD 1.1) compared with a clenched grip without aiming (mean 5.0 mm, SD 1.2, p = 0.004) and a shooting grip without aiming (mean 4.9 mm, SD 1.4, p = 0.015). The shooting grip with aiming at the index finger (mean 4.1 mm, SD 1.2) was also more accurate than a clenched grip without aiming (p = 0.006) and a shooting grip without aiming (p = 0.014). Shooting grip with aiming at the opposite index finger (median 2.0 mm, interquartile range [IQR] 1.2) showed the best precision and outperformed a clenched grip without aiming (median 2.9 mm, IQR 1.1, p = 0.016), but was not different than the shooting grip without aiming (median 2.2 mm, IQR 1.4) or the clenched grip with aiming (median 2.4 mm, IQR 1.3). The accuracy of surgeons (mean 4.1 mm, SD 1.1) was higher than the inexperienced group (mean 5.0 mm, SD 1.1, p = 0.012). The same applied for precision (median 2.2 mm, IQR 1.0 versus median 2.8 mm, IQR 1.4, p = 0.008).

CONCLUSIONS

A shooting grip combined with aiming toward the index finger of the opposite hand had better accuracy and precision compared with a clenched grip alone. Based on this study, experience does matter, because the orthopaedic surgeons outperformed the less experienced participants. Based on our study, we advise surgeons to aim at the index finger of the opposite hand when possible and to align the ipsilateral index finger to the drill bit.

LEVEL OF EVIDENCE

Level II, therapeutic study.

A Simple and Low-cost Drilling Simulator for Training Plunging Distance Among Orthopedic Surgery Residents

OBJECTIVE

Drilling through bone is a complex action that requires precise motor skills of an orthopedic surgeon. In order to minimize plunging and soft tissue damage, the surgeon must halt drill progression precisely following penetration of the far cortex. The purpose of this study was to create a low-cost and easy-to-use drilling simulator to train orthopedic residents in reducing the drill plunging depth.

DESIGN, SETTING, PARTICIPANTS

This prospective observational study was performed in the division of orthopedic surgery of a single tertiary medical center. The participants included 13 residents and 7 orthopedic specialists. The simulator consisted of a synthetic femur bone model and ordinary modeling clay, and the training unit consisted of a disposable plastic tube (∼US$14), clamps (∼US$58), and a power drill + drill bit (standard hospital equipment). Plunging depths were measured by the simulator and compared between orthopedic specialists, the 6 "senior residents" (3+ years) and the 7 "junior residents" during a training session. Measurements were taken again 2 weeks following the training session.

RESULTS

Initially, the plunging depths of the junior residents were significantly greater compared to those of the orthopedic specialists (7.00 mm vs. 5.28 mm, respectively, p < 0.038). There was no similarly significant difference between the senior residents and the orthopedic experts ([6.33 mm vs. 5.28 mm, respectively; p = 0.18). The senior residents achieved plunging depths of 5.17 mm at the end of the training session and 4.7 mm 2 weeks later compared to 7.14 mm at the end of the training session and 6 mm 2 weeks later for the junior residents.

CONCLUSIONS

This study demonstrated the capability of a low-cost drilling simulator as a training model for reducing the plunging depth during the drilling of bone and soft tissue among junior and senior residents.

Volume Manipulation Based on 3D Reconstructed Surfaces for Joint Function Evaluation and Surgery Simulation

In joint surgery, evaluation of the relative positions and angles among joint structures (bones, ligaments, muscle, and cartilages, etc.) in range of motion, lifting and weight bearing of the joint is required. However, current volume visualization techniques provide only static 3D images of anatomic structures in volume data. We propose a method to manipulate (reposition, resize and bend) the joint structures in a volume, by which surgeons can visualize and evaluate the critical positions or angles of the joint structures, and thus plan surgery to correct the morphologic pathology of the joint structures. We also propose a system with a real-time cutting simulation function together with the proposed structure manipulation functions by which surgeons can rehearse and verify joint surgery.

DEVELOPMENT OF IN-SITU TEMPERATURE PREDICTION MODELS FROM CADAVERIC HUMAN FEMUR FOR BONE DRILLING

Thermal osteonecrosis of bone in drilling procedure is caused by improper parameters which can lead to poor bone-implant integration and loss of fixation. In this study, Taguchi technique for parameter optimization and multiple regression models for temperature prediction were employed. The main aim of the study was to determine the optimal parameters of bone drilling to control the temperature rise below the thermal osteonecrosis threshold (47[Formula: see text]C) in respect of the bone density variations at different drilling directions. A 32 full factorial design with nine sets of parameters was used in the study. Drilling operations were performed along the longitudinal, radial and circumferential directions at the proximal-diaphysis, mid-diaphysis and distal-diaphysis regions of the 10 adult cadaveric femurs with different feed rates (40, 60 and 80[Formula: see text]mm/min) and spindle speeds (500, 1000 and 1500[Formula: see text]rpm) using 3.2[Formula: see text]mm diameter surgical drill bit. The in-situ drilling temperatures were measured with T-type thermocouple. The optimum drilling parameters for each drilling direction were determined from signal to noise ratios and the effect of each parameter was determined using analysis of variance. By using computed tomography scan data of patients, the proposed method is able to predict the temperature rise at the bone-drilling sites, optimal parameters and possibility for the occurrence of thermal osteonecrosis. This important tool could assist in reducing localized temperature induced from surgical drilling by up to 32% and 18[Formula: see text]C and as such significantly reduce associated osteonecrosis and improve patient outcome and quality of life.

Development of a vibration haptic simulator for shoulder arthroplasty

PURPOSE

Glenoid reaming is a technically challenging step during shoulder arthroplasty that could possibly be learned during simulation training. Creation of a realistic simulation using vibration feedback in this context is innovative. Our study focused on the development and internal validation of a novel glenoid reaming simulator for potential use as a training tool.

METHODS

Vibration and force profiles associated with glenoid reaming were quantified during a cadaveric experiment. Subsequently, a simulator was fabricated utilizing a haptic vibration transducer with high- and low-fidelity amplifiers; system calibration was performed matching vibration peak-peak values for both amplifiers. Eight experts performed simulated reaming trials. The experts were asked to identify isolated layer profiles produced by the simulator. Additionally, experts' efficiency to successfully perform a simulated glenoid ream based solely on vibration feedback was recorded.

RESULTS

Cadaveric experimental cartilage reaming produced lower vibrations compared to subchondral and cancellous bones ([Formula: see text]). Gain calibration of a lower-fidelity (3.5 [Formula: see text] and higher-fidelity (3.4 [Formula: see text] amplifier resulted in values similar to the cadaveric experimental benchmark (3.5 [Formula: see text]. When identifying random tissue layer samples, experts were correct [Formula: see text] of the time and success rate varied with tissue type ([Formula: see text]). During simulated reaming, the experts stopped at the targeted subchondral bone with a success rate of [Formula: see text]. The fidelity of the simulation did not have an effect on accuracy, applied force, or reaming time ([Formula: see text]). However, the applied force tended to increase with trial number ([Formula: see text]).

CONCLUSIONS

Development of the glenoid reaming simulator, coupled with expert evaluation furthered our understanding of the role of haptic vibration feedback during glenoid reaming. This study was the first to (1) propose, develop and examine simulated glenoid reaming, and (2) explore the use of haptic vibration feedback in the realm of shoulder arthroplasty.

An advanced simulator for orthopedic surgical training

PURPOSE

The purpose of creating the virtual reality (VR) simulator is to facilitate and supplement the training opportunities provided to orthopedic residents. The use of VR simulators has increased rapidly in the field of medical surgery for training purposes. This paper discusses the creation of the virtual surgical environment (VSE) for training residents in an orthopedic surgical process called less invasive stabilization system (LISS) surgery which is used to address fractures of the femur.

METHOD

The overall methodology included first obtaining an understanding of the LISS plating process through interactions with expert orthopedic surgeons and developing the information centric models. The information centric models provided a structured basis to design and build the simulator. Subsequently, the haptic-based simulator was built. Finally, the learning assessments were conducted in a medical school.

RESULTS

The results from the learning assessments confirm the effectiveness of the VSE for teaching medical residents and students. The scope of the assessment was to ensure (1) the correctness and (2) the usefulness of the VSE. Out of 37 residents/students who participated in the test, 32 showed improvements in their understanding of the LISS plating surgical process. A majority of participants were satisfied with the use of teaching Avatars and haptic technology. A paired t test was conducted to test the statistical significance of the assessment data which showed that the data were statistically significant.

CONCLUSION

This paper demonstrates the usefulness of adopting information centric modeling approach in the design and development of the simulator. The assessment results underscore the potential of using VR-based simulators in medical education especially in orthopedic surgery.

Mechanical model of orthopaedic drilling for augmented-haptics-based training

In this study, augmented-haptic feedback is used to combine a physical object with virtual elements in order to simulate anatomic variability in bone. This requires generating levels of force/torque consistent with clinical bone drilling, which exceed the capabilities of commercially available haptic devices. Accurate total force generation is facilitated by a predictive model of axial force during simulated orthopaedic drilling. This model is informed by kinematic data collected while drilling into synthetic bone samples using an instrumented linkage attached to the orthopaedic drill. Axial force is measured using a force sensor incorporated into the bone fixture. A nonlinear function, relating force to axial position and velocity, was used to fit the data. The normalized root-mean-square error (RMSE) of forces predicted by the model compared to those measured experimentally was 0.11 N across various bones with significant differences in geometry and density. This suggests that a predictive model can be used to capture relevant variations in the thickness and hardness of cortical and cancellous bone. The practical performance of this approach is measured using the Phantom Premium haptic device, with some required customizations.

Effectiveness of a Low-Cost Drilling Module in Orthopaedic Surgical Simulation

INTRODUCTION

Financial pressures and resident work hour regulations have led to adjunct means of resident education such as surgical simulation. The purpose of this study is to determine the effectiveness of a hands-on training session in orthopaedic drilling technique educational model during a surgical simulation on reducing drill plunging depth and to determine the effectiveness of senior residents teaching a hands-on training session in orthopaedic drilling technique.

METHODS

A total of 13 participants (5 orthopaedic interns and 8 medical students) drilled until they penetrated the far cortex of a synthetic bone model and the plunging depth (PD) was measured. They were then randomized and underwent an education session with an attending orthopaedic surgeon or a senior resident. Next, the subjects drilled again with the PD being calculated. The preeducational and posteducational session were compared to determine if there was any improvement in PD and if there was a difference between educators. The cost of the model was also determined.

RESULTS

The mean maximum PD and mean PD before the education session was 1.58 (1.40-2.10) and 1.50cm (1.36-1.76), respectively. Following the educational session, the mean maximum PD and mean PD were 0.53 (0.42-0.75) and 0.50cm (0.40-0.72), respectively. These were both significantly lower than before the education session (p <0.05). After the educational session taught by the attending versus the session taught by the resident, the mean maximum PD was 0.59 (0.42-0.75) and 0.49cm. (0.45-0.75), respectively (p = 0.44). After the educational session taught by the attending versus the session taught by the resident, the mean PD was 0.54 (0.40-0.72) and 0.47cm. (0.40-0.65), respectively (p = 0.44). The cost of the station per participant was $5.44.

CONCLUSION

This study demonstrated a significant reduction in drilling PD with use of a low-cost training model and a formal didactic and skills session on proper drilling technique that can effectively be led by senior residents.

In-vitro analysis of forces in conventional and ultrasonically assisted drilling of bone

BACKGROUND

Drilling of bone is widely performed in orthopaedics for repair and reconstruction of bone. Current paper is focused on the efforts to minimize force generation during the drilling process. Ultrasonically Assisted Drilling (UAD) is a possible option to replace Conventional Drilling (CD) in bone surgical procedures.

OBJECTIVE

The purpose of this study was to investigate and analyze the effect of drilling parameters and ultrasonic parameters on the level of drilling thrust force in the presence of water irrigation.

METHODS

Drilling tests were performed on young bovine femoral bone using different parameters such as spindle speeds, feed rates, coolant flow rates, frequency and amplitudes of vibrations.

RESULTS

The drilling force was significantly dropped with increase in drill rotation speed in both types of drilling. Increase in feed rate was more influential in raising the drilling force in CD compared to UAD. The force was significantly dropped when ultrasonic vibrations up to 10 kHz were imposed on the drill. The drill force was found to be unaffected by the range of amplitudes and the amount of water supplied to the drilling region in UAD.

CONCLUSIONS

Low frequency vibrations with irrigation can be successfully used for safe and efficient drilling in bone.

A review of virtual reality based training simulators for orthopaedic surgery

This review presents current virtual reality based training simulators for hip, knee and other orthopaedic surgery, including elective and trauma surgical procedures. There have not been any reviews focussing on hip and knee orthopaedic simulators. A comparison of existing simulator features is provided to identify what is missing and what is required to improve upon current simulators. In total 11 hip replacements pre-operative planning tools were analysed, plus 9 hip trauma fracture training simulators. Additionally 9 knee arthroscopy simulators and 8 other orthopaedic simulators were included for comparison. The findings are that for orthopaedic surgery simulators in general, there is increasing use of patient-specific virtual models which reduce the learning curve. Modelling is also being used for patient-specific implant design and manufacture. Simulators are being increasingly validated for assessment as well as training. There are very few training simulators available for hip replacement, yet more advanced virtual reality is being used for other procedures such as hip trauma and drilling. Training simulators for hip replacement and orthopaedic surgery in general lag behind other surgical procedures for which virtual reality has become more common. Further developments are required to bring hip replacement training simulation up to date with other procedures. This suggests there is a gap in the market for a new high fidelity hip replacement and resurfacing training simulator.

The trends and challenges in orthopaedic simulation

Generally, in some universities of medicine, orthopaedic training procedures represent a difficult task due to the inadequacies of the systems, the resources, and the use of technologies. This article explains the challenges and the needs for more research in the issue of orthopaedic simulation around the world.

Simulation and evaluation of a bone sawing procedure for orthognathic surgery based on an experimental force model

Bone sawing is widely used in orthognathic surgery to correct maxillary deformities. Successful execution of bone sawing requires a high level of dexterity and experience. A virtual reality (VR) surgical simulator can provide a safe, cost-effective, and repeatable training method. In this study, we developed a VR training simulator with haptic functions to simulate bone-sawing force, which was generated by the experimental force model. Ten human skulls were obtained in this study for the determination of surgical bone-sawing force. Using a 5-DOF machining center and a micro-reciprocating saw, bone specimens with different bone density were sawed at different feed rates (20, 40, and 60 mm/min) and spindle speeds (9800, 11,200 and 12,600 cycles per minute). The sawing forces were recorded with a piezoelectric dynamometer and a signal acquisition system. Linear correlation analysis of all experimental data indicates that there were significant positive linear correlations between bone-sawing force and bone density and tool feed rate and a moderate negative linear correlation with tool spindle rate. By performing multiple regression analysis, the prediction models for the bone-sawing procedure were determined. By employing Omega.6 as a haptic device, a medical simulator for the Lefort I osteotomy was developed based on an experimental force model. Comparison of the force-time curve acquired through experiments and the curve computed from the simulator indicate that the obtained forces based on the experimental force model and the acquired data had the same trend for the bone-sawing procedure of orthognathic surgery.

Effects of gamma radiation sterilization and strain rate on compressive behavior of equine cortical bone

OBJECTIVES

Gamma radiation has been widely used for sterilization of bone allograft. However, sterilization by gamma radiation damages the material properties of bone which is a major clinical concern since bone allograft is used in load bearing applications. While the degree of this damage is well investigated for quasi-static and cyclic loading conditions, there does not appear any information on mechanical behavior of gamma-irradiated cortical bone at high speed loading conditions. In this study, the effects of gamma irradiation on high strain rate compressive behavior of equine cortical bone were investigated using a Split Hopkinson Pressure Bar (SHPB). Quasi-static compression testing was also performed.

METHODS

Equine cortical bone tissue from 8year old retired racehorses was divided into two groups: non-irradiated and gamma-irradiated at 30kGy. Quasi-static and high strain rate compression tests were performed at average strain rates of 0.0045/s and 725/s, respectively.

RESULTS

Agreeing with previous results on the embrittlement of cortical bone when gamma-irradiated, the quasi-static results showed that gamma-irradiation significantly decreased ultimate strength (9%), ultimate strain (27%) and toughness (41%), while not having significant effect on modulus of elasticity, yield strain and resilience. More importantly, contrary to what is typically observed in quasi-static loading, the gamma-irradiated bone under high speed loading showed significantly higher modulus of elasticity (45%), ultimate strength (24%) and toughness (26%) than those of non-irradiated bone, although the failure was at a similar strain.

SIGNIFICANCE

Under high speed loading, the mechanical properties of bone allografts were not degraded by irradiation, in contrast to the degradation measured in this and prior studies under quasi-static loading. This result calls into question the assumption that bone allograft is always degraded by gamma irradiation, regardless of loading conditions. However, it needs further investigation to be translated positively in a clinical setting.

Predictive force model for haptic feedback in bone sawing

Bone sawing simulators with force feedback represent a cost effective means of training orthopedic surgeons in various surgical procedures, such as total knee arthroplasty. To develop a machine with accurate haptic feedback, giving a sensation of both cutting force and rate of material removal, algorithms are required to forecast bone sawing forces based on user input. Presently, studies on forces generated while machining bone are not representative of the high cutting speeds and low depths of cut common to the bone sawing process. The objective of this research was to quantify sawing forces in cortical bone as a function of blade speed and depth of cut. A fixture was developed to simulate linear bone sawing over a range of speeds comparable to surgical reciprocating and oscillating (sagittal) bone saws. A single saw blade tooth was isolated and used to create a slotted cut in bovine cortical bone. Over a range in linear sawing speed from 1700 to 7000 mm/s, a t-test (α=0.05) revealed there was no statistically significant effect of blade speed on either cutting or thrust force. However, an increase in depth of cut from 2 to 10 μm resulted in a 30% increase in thrust force, while cutting force remained constant. The increase in thrust force with depth of cut was relatively linear, R(2)=0.80. Using a two factor, two level design of experiments approach, regression equations were developed to relate sawing forces to changes in blade speed and depth of cut. These equations can be used to predict forces in a haptic feedback model.

Biomechanical Measurements of Surgical Drilling Force and Torque in Human Versus Artificial Femurs

Few experimental studies have examined surgical drilling in human bone, and no studies have inquired into this aspect for a popular commercially-available artificial bone used in biomechanical studies. Sixteen fresh-frozen human femurs and five artificial femurs were obtained. Cortical specimens were mounted into a clamping system equipped with a thrust force and torque transducer. Using a CNC machine, unicortical holes were drilled in each specimen at 1000 rpm, 1250 rpm, and 1500 rpm with a 3.2 mm diameter surgical drill bit. Feed rate was 120 mm/min. Statistical significance was set at p < 0.05. Force at increasing spindle speed (1000 rpm, 1250 rpm, and 1500 rpm), respectively, showed a range for human femurs (198.4 ± 14.2 N, 180.6 ± 14.0 N, and 176.3 ± 11.2 N) and artificial femurs (87.2 ± 19.3 N, 82.2 ± 11.2 N, and 75.7 ± 8.8 N). For human femurs, force at 1000 rpm was greater than at other speeds (p ≤ 0.018). For artificial femurs, there was no speed effect on force (p ≥ 0.991). Torque at increasing spindle speed (1000 rpm, 1250 rpm, and 1500 rpm), respectively, showed a range for human femurs (186.3 ± 16.9 N·mm, 157.8 ± 16.1 N·mm, and 140.2 ± 16.4 N·mm) and artificial femurs (67.2 ± 8.4 N·mm, 61.0 ± 2.9 N·mm, and 53.3 ± 2.9 N·mm). For human femurs, torque at 1000 rpm was greater than at other speeds (p < 0.001). For artificial femurs, there was no difference in torque for 1000 rpm versus higher speeds (p ≥ 0.228), and there was only a borderline difference between the higher speeds (p = 0.046). Concerning human versus artificial femurs, their behavior was different at every speed (force, p ≤ 0.001; torque, p < 0.001). For human specimens at 1500 rpm, force and torque were linearly correlated with standardized bone mineral density (sBMD) and the T-score used to clinically categorize bone quality (R ≥ 0.56), but there was poor correlation with age at all speeds (R ≤ 0.37). These artificial bones fail to replicate force and torque in human cortical bone during surgical drilling. To date, this is the largest series of human long bones biomechanically tested for surgical drilling.

Force and torque modelling of drilling simulation for orthopaedic surgery

The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with an excellent tool for training and preoperative planning purposes. This is especially true for procedures involving the drilling of bone, which require a great amount of adroitness and experience due to difficulties arising from vibration and drill bit breakage. 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. Clogging was observed for feed rates greater than 0.5 mm/s and spindle speeds less than 2500 rpm. The drilling simulation systems that have been created to date do not address the issue of drill flute clogging. This paper presents force and torque prediction models that account for this phenomenon. The two coefficients of friction required by these models were determined via a set of calibration experiments. The accuracy of both models was evaluated by an additional set of validation experiments resulting in average R² regression correlation values of 0.9546 and 0.9209 for the force and torque prediction models, respectively. The resulting models can be adopted by haptic simulation systems to provide a more realistic tactile output.