Advancing computer-assisted orthopaedic surgery using a hexapod device for closed diaphyseal fracture reduction

An Integrated Method of Biomechanics Modeling for Pelvic Bone and Surrounding Soft Tissues

The pelvis and its surrounding soft tissues create a complicated mechanical environment that greatly affects the success of fixing broken pelvic bones with surgical navigation systems and/or surgical robots. However, the modeling of the pelvic structure with the more complex surrounding soft tissues has not been considered in the current literature. The study developed an integrated finite element model of the pelvis, which includes bone and surrounding soft tissues, and verified it through experiments. Results from the experiments showed that including soft tissue in the model reduced stress and strain on the pelvis compared to when it was not included. The stress and strain distribution during pelvic loading was similar to what is typically seen in research studies and more accurate in modeling the pelvis. Additionally, the correlation with the experimental results from the predecessor's study was strong (R² = 0.9627). The results suggest that the integrated model established in this study, which includes surrounding soft tissues, can enhance the comprehension of the complex biomechanics of the pelvis and potentially advance clinical interventions and treatments for pelvic injuries.

Intelligent robot-assisted minimally invasive reduction system for reduction of unstable pelvic fractures

OBJECTIVE

Currently, minimally invasive internal fixation is recommended for the surgical treatment of unstable pelvic fractures. The premise and difficulty of minimally invasive internal fixation are minimally invasive reduction of fractures. This review aimed to investigate the indications, surgical strategy and techniques, safety, and efficacy of intelligent robot-assisted fracture reduction (RAFR) system of pelvic ring injuries.

METHODS

This retrospective study reviewed a case series from March 2021 to November 2021. A total of 22 patients with unstable pelvic fracture injuries underwent minimally invasive internal fixations. All pelvic ring fractures were reduced with our intelligent RAFR system. The robot system intelligently designs the optimal position and reduction path based on the patient's preoperative 3D CT. During the operation, the three-dimensional visualization of the fracture is realized through image registration, and the Robot completes the automatic reduction of the fracture. The global 3D point cloud error between the preoperative planning results and the actual postoperative reduction results was calculated. The postoperative reduction results of residual displacement were graded by the Matta Criteria.

RESULTS

Minimally invasive closed reduction procedures were completed in all 22 cases with our RAFR system. The average global 3D point cloud reduction error between the preoperative planning results and the actual postoperative reduction results was 3.41mm±1.83mm. The mean residual displacement was 4.61mm±3.29mm. Given the Matta criteria, 16 cases were excellent, five were good, and one was fair, with an excellent and good rate of 95.5%.

CONCLUSION

Our new pelvic fracture reduction robot system can complete intelligent and minimally invasive fracture reduction for most patients with unstable pelvic fractures. The system has intelligent reduction position and path planning and realizes stable pelvis control through a unique holding arm and a robotic arm. The operation process will not cause additional damage to the patient, which fully meets the clinical requirements. Our study demonstrated the safety and effectiveness of our robotic reduction system and its applicability and usability in clinical practice, thus paving the way towards Robot minimally invasive pelvic fracture surgeries.

Robot-patient registration for optical tracker-free robotic fracture reduction surgery

BACKGROUND AND OBJECTIVE

Image-guided robotic surgery for fracture reduction is a medical procedure in which surgeons control a surgical robot to align the fractured bones by using a navigation system that shows the rotation and distance of bone movement. In such robotic surgeries, it is necessary to estimate the relationship between the robot and patient (bone), a task known as robot-patient registration, to realize the navigation. Through the registration, a fracture state in real-world can be simulated in virtual space of the navigation system.

METHODS

This paper proposes an approach to realize robot-patient registration for an optical-tracker-free robotic fracture-reduction system. Instead of the optical tracker which is a three-dimensional position localizer, X-ray images are used to realize the robot-patient registration, combining the relationship of both the robot and patient with regards to C-arm. The proposed method consists of two steps of registration, where initial registration is followed by refined registration which adopts particle swarm optimization with the minimum cross-reprojection error based on bidirectional X-ray images. To address the unrecognizable features due to interference between the robot and bone, we also developed attachable robot features. The allocated robot features could be clearly extracted from the X-ray images, and precise registration could be realized through the particle swarm optimization.

RESULTS

The proposed method was evaluated in phantom and ex-vivo experiments involving a caprine cadaver. For the phantom experiments, the average translational and rotational errors were 1.88 mm and 2.45°, respectively, and the corresponding errors in the ex vivo experiments were 2.64 mm and 3.32° The results demonstrated the effectiveness of the proposed robot-patient registration.

CONCLUSIONS

The proposed method enable to estimate the three-dimensional relationship between fractured bones in real-world by using only two-dimensional images, and the relationship is accurately simulated in virtual reality for the navigation. Therefore, a reduction procedure for successful treatment of bone fractures in image-guided robotic surgery can be expected with the aid of the proposed registration method.

Sensor technology usage in orthopedic trauma

Medicine in general is quickly transitioning to a digital presence. Orthopaedic surgery is also being impacted by the tenets of digital health but there are also direct efforts with trauma surgery. Sensors are the pen and paper of the next wave of data acquisition. Orthopaedic trauma can and will be part of this new wave of medicine. Early sensor products that are now coming to market, or are in early development, will directly change the way we think about surgical diagnosis and outcomes. Sensor development for biometrics is already here. Wellness devices, pressure, temperature, and other parameters are already being measured. Data acquisition and analysis is going to be a fruitful addition to our research armamentarium with the volume of information now available. A combination of broadband internet, micro electrical machine systems (MEMS), and new wireless communication standards is driving this new wave of medicine. The Internet of Things (IoT) [1] now has a subset which is the Internet of Medical Devices [2-5] permitting a much more in-depth dive into patient procedures and outcomes. IoT devices are now being used to enable remote health monitoring, in hospital treatment, and guide therapies. This article reviews current sensor technology that looks to impact trauma care.

Marker- three dimensional measurement versus traditional radiographic measurement in the treatment of tibial fracture using Taylor spatial frame

Background

The Taylor Spatial Frame (TSF) has been widely used for tibial fracture. However, traditional radiographic measurement method is complicated and the reduction accuracy is affected by various factors. The purpose of this study was to propose a new marker- three dimensional (3D) measurement method and determine the differences of reduction outcomes, if any, between marker-3D measurement method and traditional radiographic measurement in the TSF treatment.

Methods

Forty-one patients with tibial fracture treated by TSF in our institution were retrospectively analyzed from January 2016 to June 2019, including 21 patients in the marker-3D measurement group (experimental group) and 20 patients in the traditional radiographic measurement group (control group). In the experimental group, 3D reconstruction with 6 markers installed on the TSF was performed to determine the electronic prescription. In the control group, the anteroposterior (AP) and lateral radiographs were performed for the traditional parameter measurements. The effectiveness was evaluated by the residual displacement deformity (RDD) and residual angle deformity (RAD) in the coronal and sagittal plane, according to the AP and lateral X-rays after reduction.

Results

All patients achieved functional reduction. The residual RDD in AP view was 0.5 (0, 1.72) mm in experimental group and 1.74 (0.43, 3.67) mm in control group. The residual RAD in AP view was 0 (0, 1.25) ° in experimental group and 1.25 (0.62, 1.95) °in control group. As for the lateral view, the RDD was 0 (0, 1.22) mm in experimental group and 2.02 (0, 3.74) mm in control group, the RAD was 0 (0, 0) ° in experimental group and 1.42 (0, 1.93) ° in control group. Significant differences in all above comparisons were observed between the two groups (AP view RDD: P = 0.024, RAD: P = 0.020; Lateral view RDD: P = 0.016, RAD: P = 0.004).

Conclusions

The present study introduced a marker-3D measurement method to complement the current TSF treatment. This method avoids the manual measurement error and improves the accuracy of fracture reduction, providing potential advantages of bone healing and function rehabilitation.

Constraint of musculoskeletal tissue and path planning of robot-assisted fracture reduction with collision avoidance

BACKGROUND

For the robot-assisted fracture reduction, due to the complex fracture musculoskeletal environment, it is necessary to consider the influence of soft tissue traction on preoperative reduction path planning.

METHOD

An improved 3D A* algorithm is adopted to plan the fracture reduction path. The distal fragment point clouds are updated to avoid the collision, and the end point coordinates of the muscles are updated to calculate muscular lengths during the path search.

RESULTS

3D reduction path of long-bone fracture is planned, effectively avoiding the fracture fragments collision and ensuring the length of the corresponding muscle is always less than the allowable maximum muscle length after elongation.

CONCLUSION

The proposed method can effectively avoid the collision between the distal fragment and the proximal fragment during the fracture reduction, can avoid secondary injury of the muscles around the femoral bone caused by over-distraction, and effectively improve the safety of robot reduction operation. This article is protected by copyright. All rights reserved.

Hill-based musculoskeletal model for a fracture reduction robot

BACKGROUND

The introduction of fracture reduction robot can solve the problem of large reduction forces during fracture reduction surgeries and the need to collect multiple medical images. However, because its safety has not been certified, there are few academic achievements on this type of robot. To calculate the safety factor during its operation, a musculoskeletal model needs to be established to study the constraints of muscles on the robot. The existing academic achievements of musculoskeletal modelling are mainly for application such as rehabilitation treatment and collision in car accidents.

METHODS

A musculoskeletal model applied to the fracture reduction robot is proposed in this paper. First, by comparing the characteristics of mainstream muscle models and combining the biological characteristics of the anesthetised muscles, the Hill model was selected as the muscle model for this study. Second, based on the motion composition of six spatial degrees of freedom, five basic fractural malposition situations are proposed. Then, a 170-cm tall male musculoskeletal model was built in Opensim. Based on this model, the muscle force curves of the above malposition situations are calculated. Finally, a similar musculoskeletal model was established in Adams, and the accuracy of its muscle force data was tested. The study is approved by the ethics committee of the Rehabilitation Hospital, National Research Center for Rehabilitation Technical Aids, Beijing, China.

RESULTS

The muscle force curve of Opensim and Adams model under situations of five basic malposition are compared. Most of the correlation coefficients are in the range of 0.98-0.99. The overall correlation coefficient is greater than 0.95.

CONCLUSIONS

The simulation results prove that this model can be used for the safety assessment of the fracture reduction robots. This model will be served as an environmental constraint to study the control of fracture reduction robot.

Kinematic Analysis and Design of a Six-Degrees of Freedom 3-RRPS Mechanism for Bone Reduction Surgery

Robot-assisted bone reduction surgery consists in using robots to reposition the bone fragments into their original place prior to fracture healing. This study presents the application of a 3-RRPS augmented tripod mechanism with six degrees-of-freedom for longitudinal bone reduction surgery. First, the inverse and forward kinematic models of the mechanism are investigated. Particularly, the forward kinematic is solved by applying Sylvester's dialytic method. Second, the velocity model is studied and its singular configurations are identified. The workspace of the 3-RRPS mechanism is then outlined and compared with the Stewart platform, which is a classical mechanism for the targeted application. The results show that this mechanism provides a larger workspace, especially its rotation angle about the vertical axis, which is an important aspect in the bone reduction. A series of simulations on the numerical and graphic software is performed to verify the entire analysis of the parallel mechanism. A physiguide and mscadams software are used to carry out a simulation of a real case of femur fracture reduction using the proposed mechanism to validate its suitability. Finally, a robotic prototype based on the mechanism is manufactured and experimented using an artificial bone model to evaluate the feasibility of the mechanism.

Comparison of three different correction trajectories for foot and ankle deformity treated by supramalleolar osteotomy using a novel external fixator

Based on the principle of distraction osteogenesis, external fixators are widely used in deformity correction of the foot and ankle. In this study, a novel ankle external fixator is proposed to correct complex multiplane deformities, especially for supramalleolar osteotomy to correct distal tibia deformities. The relatively simple structure and fewer struts in the proposed fixator reduce the complexity of adjusting the external fixator. Based on two existing adjustment strategies, a new strategy taking into account the orientation and shortest path of the ankle joint center is proposed, which is named joint adjustment for equal bone distraction. By proposing the inverse kinematic solutions of the novel external fixator, mathematical derivations of the bone trajectory and modelling of the bone shape for the three distraction strategies are performed. The results obtained by comparative analysis indicate that a uniformly spaced path of the ankle joint center can be acquired, and a smooth and uniform correction trajectory of the distal tibia end can be obtained using the new adjustment strategy. It can avoid bone end interference and only generates a maximum deviation 0.66% greater than the currently optimal 1 mm/day. The new strategy can perform multiplane corrections simultaneously, which shortens the correction time and reduces the patient's pain.

Application of binocular visual navigation technique in diaphyseal fracture reduction

BACKGROUND

Computer-assisted surgical navigation techniques have shown promise; however, currently popular systems have limitations. This paper presents the characterization and application of a binocular visual navigation technique in diaphyseal fracture reduction.

METHODS

A binocular visual tracker (MicronTracker) was introduced to reduce diaphyseal fractures. A transformation matrix was used to acquire the reduction parameters. A transverse diaphyseal fracture was used as a control group.

RESULTS

Precision tests were performed with the binocular system using a simulation femoral model with a transverse fracture 12 times. All residual deformations were compared and P < 0.01.

CONCLUSIONS

The binocular visual navigation technique produces good results with advantages of flexibility and high positional accuracy and shows promise. The MicronTracker might lead to further application in the remote navigation field.

Recent Trends, Technical Concepts and Components of Computer-Assisted Orthopedic Surgery Systems: A Comprehensive Review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.

Medical Robotics in Bone Fracture Reduction Surgery: A Review

Since the advantages of precise operation and effective reduction of radiation, robots have become one of the best choices for solving the defects of traditional fracture reduction surgery. This paper focuses on the application of robots in fracture reduction surgery, design of the mechanism, navigation technology, robotic control, interaction technology, and the bone-robot connection technology. Through literature review, the problems in current fracture reduction robot and its future development are discussed.

Early Experience with Reduction of Unstable Pelvic Fracture Using a Computer-Aided Reduction Frame

Purpose

The optimal closed reduction technique for unstable pelvic fractures remains controversial. The purpose of this study is to verify the effectiveness and report early experiences with the reduction of unstable pelvic fractures using a computer-aided pelvic reduction frame.

Methods

From January 2015 to August 2016, a total of 10 patients with unilateral unstable pelvic fractures were included in this study. The surgical reduction procedure was based on the protocol of the computer-aided pelvic reduction frame that we proposed in a previous work. The quality of the reductions achieved using this system was evaluated with residual translational and rotational differences between the actual and virtual reduction positions of pelvis. The duration of the operation was recorded for quality control.

Results

The mean times required to set up the frame, to complete the virtual surgery simulation, and to reduce the unstable pelvic fractures were 10.3, 20.9, and 7.5 min, respectively. The maximum residual translational and rotational displacements were less than 6.5 mm and 3.71 degrees, respectively.

Conclusions

This computer-aided reduction frame can be a useful tool for the speedy and accurate reduction of unstable pelvic fractures. Further clinical studies should be conducted with larger patient samples to verify its safety and efficacy.

Minimally invasive treatment of displaced femoral shaft fractures with a teleoperated robot-assisted surgical system

BACKGROUND

Minimally invasive surgical operation of intramedullary (IM) nailing is a standard technique for treating diaphyseal fractures. However, in addition to its advantages, there are some drawbacks such as the frequent occurrence of malalignment, physical fatigue and high radiation exposure to medical staff. The use of robotic and navigation techniques is promising treatments for femoral fractures.

MATERIALS AND METHODS

This paper presents a novel robot-assisted manipulator for femoral shaft fracture reduction with indirect contact with the femur. An alternative clinical testing model was proposed for orthopedic surgeons to practice femoral fracture reduction. This model imitates the human musculoskeletal system in shape and functional performance. The rubber tube simulate muscles providing contraction forces, and the silicone simulates passive elasticity of muscles. Two-group experiments were performed for studying feasibility of the teleoperated manipulator.

RESULTS

The average operative time was about 7min. In the first group experiments, the femur axial, antero-posterior (AP) and lateral views mean errors were 2.2mm, 0.7mm and 1.1mm, respectively, and their maximums were 3.0mm, 0.9mm and 1.5mm; the mean errors of rotation were 0.8° around x-axis, 1.6° around y-axis, 2.0° around z-axis, and their maximums were 1.1°, 2.2°, 2.9°, respectively. For the second group experiments, the femur axial, AP and lateral views mean errors were 1.8mm, 0.4mm and 0.8mm, respectively, and their maximums were 2.2mm, 0.7mm and 1.1mm; the mean errors of rotation were 1.2° around x-axis, 1.6° around y-axis, 1.9° around z-axis, and their maximums were 2.4°, 1.8°, 2.7°, respectively. Reduction for AP view displacement is easier than lateral (p<0.05) because of the tube-shaped anatomy and the muscle contraction forces. Errors around x-axis are smaller than those around y-, and z- axes (p<0.05), i.e., electro-mechanical actuator is easier to control than pneumatic.

CONCLUSION

An experimental model for simulating human femoral characteristics was proposed. Experiments conducted on the artificial lower limb model demonstrated high reduction accuracy, safety, sufficient working space, and low radiation exposure of the proposed robot-assisted system. Thus, the minimally invasive teleoperated manipulator would have greater development prospect.

A new hand-eye calibration approach for fracture reduction robot

OBJECTIVE

The hand-eye calibration is used to determine the transformation between the end-effector and the camera marker of the robot. But the robot movement in traditional method would be time-consuming, inaccurate and even unavailable in some conditions. The method presented in this article can complete the calibration without any movement and is more suitable in clinical applications.

METHODS

Instead of solving the classic non-linear equation AX = XB, we collected the points on X and Y axes of the tool coordinate system (TCS) with the visual probe and fitted them using the singular value decomposition algorithm (SVD). Then, the transformation was obtained with the data of the tool center point (TCP). A comparison test was conducted to verify the performance of the method.

RESULTS

The average translation error and orientation error of the new method are 0.12 ± 0.122 mm and 0.18 ± 0.112° respectively, while they are 0.357 ± 0.347 mm and 0.416 ± 0.234° correspondingly in the traditional method.

CONCLUSIONS

The high accuracy of the method indicates that it is a good candidate for medical robots, which usually need to work in a sterile environment.

Robotic surgical systems in maxillofacial surgery: a review

Throughout the twenty-first century, robotic surgery has been used in multiple oral surgical procedures for the treatment of head and neck tumors and non-malignant diseases. With the assistance of robotic surgical systems, maxillofacial surgery is performed with less blood loss, fewer complications, shorter hospitalization and better cosmetic results than standard open surgery. However, the application of robotic surgery techniques to the treatment of head and neck diseases remains in an experimental stage, and the long-lasting effects on surgical morbidity, oncologic control and quality of life are yet to be established. More well-designed studies are needed before this approach can be recommended as a standard treatment paradigm. Nonetheless, robotic surgical systems will inevitably be extended to maxillofacial surgery. This article reviews the current clinical applications of robotic surgery in the head and neck region and highlights the benefits and limitations of current robotic surgical systems.

[Clinical application of computer-assisted cannulated screw internal fixation system based on error correction method for femoral neck fractures]

Objective

To investigate the clinical efficacy of computer-assisted cannulated screw internal fixation system based on error correction method for femoral neck fractures.

Methods

A retrospective analysis was made on the clinical data of 20 femoral neck fracture patients treated by computer-assisted cannulated screw internal fixation system based on error correction method between January 2014 and October 2015 (trial group), and 36 femoral neck fracture patients undergoing traditional manual surgery with closed reduction by cannulated screw fixation in the same period (the control group). There was no significant difference in gender, age, injury cause, side of fracture, types of fracture, and time from injury to operation between 2 groups ( P>0.05). The operation time, intraoperative blood loss, intraoperative frequency of fluoroscopy and guide pin insertion, fracture healing time, fracture healing rate, and Harris hip score were compared between 2 groups.

Results

All incisions healed by first intention after operation, and no complication of blood vessel and nerve injury occurred. The operation time of trial group was significantly longer than that of control group ( t=2.290, P=0.026), however, the intraoperative blood loss, intraoperative frequency of fluoroscopy and guide pin insertion of trial group were significantly less than those of control group ( t=-10.650, P=0.000; t=18.320, P=0.000; t=-16.625, P=0.000). All patients were followed up 12-18 months (mean, 14.7 months). X-ray films showed that fracture healing was obtained in 2 groups, showing no significant difference in fracture healing time between 2 groups ( t=0.208, P=0.836). No complication of ischemic necrosis of femoral head occurred during follow-up period. At last follow-up, the Harris hip score was 87.05±3.12 in trial group and was 86.78±2.83 in control group, showing no significant difference ( t=0.333, P=0.741).

Conclusion

Computer-assisted cannulated screw internal fixation surgery based on error correction method for femoral neck fractures is better than traditional manual surgery in decreasing intraoperative radiation and surgical trauma during operation.

PHYSICAL SYMMETRY AND VIRTUAL PLANE-BASED REDUCTION REFERENCE: A PRELIMINARY STUDY FOR ROBOT-ASSISTED PELVIC FRACTURE REDUCTION

Traditional pelvis fracture reduction suffers from some disadvantages. Robot-assisted pelvis fracture reduction offers some promise in solving these problems. However, the reduction reference to guide robot motion is a key issue that must be resolved. In this paper, we propose a physical symmetry and virtual plane-based reduction reference and adopt the method of registration to calculate the virtual plane for the reference, which were verified via experiments. The results of the position symmetry experiments of the original pelvis and virtual plane-based position symmetry experiments were similar; both showed that the symmetry errors of the pelvis were less than 4[Formula: see text]mm and 2.5[Formula: see text]. The results indicated that the proposed method could be used as a reference for robot-assisted pelvis fracture reduction.

A visual servo-based teleoperation robot system for closed diaphyseal fracture reduction

Common fracture treatments include open reduction and intramedullary nailing technology. However, these methods have disadvantages such as intraoperative X-ray radiation, delayed union or nonunion and postoperative rotation. Robots provide a novel solution to the aforementioned problems while posing new challenges. Against this scientific background, we develop a visual servo-based teleoperation robot system. In this article, we present a robot system, analyze the visual servo-based control system in detail and develop path planning for fracture reduction, inverse kinematics, and output forces of the reduction mechanism. A series of experimental tests is conducted on a bone model and an animal bone. The experimental results demonstrate the feasibility of the robot system. The robot system uses preoperative computed tomography data to realize high precision and perform minimally invasive teleoperation for fracture reduction via the visual servo-based control system while protecting surgeons from radiation.