Quantitative assessment of parkinsonian bradykinesia based on an inertial measurement unit.

BACKGROUND: As the most characteristic feature of Parkinson's disease (PD), bradykinesia (slowness of movement) affects all patients with Parkinson's disease and interferes with their daily activities. This study introduces a wearable bradykinesia assessment system whose core component is composed of an inertial measurement unit. METHODS: The system diagram and assessment task were defined in accordance with clinical requirements from neurologists. Based on hand grasping actions, calculations of hand grasping ranges and statistical methods of quantitatively assessing parkinsonian bradykinesia were presented. Seven control subjects and eight patients were tested with this system. RESULTS: Experimental results show that a calculated bradykinesia parameter (modified mean range, instead of mean and standard deviation of the grasp ranges) correlated well with the evaluations of a neurologist (Pearson's correlation coefficient r = -0.83, p < 0.001). CONCLUSIONS: The bradykinesia assessment system was tested on both health subjects and PD patients. The results show that this system has greater correlation with the evaluations by neurologists than other parkinsonian bradykinesia assessment systems. The modified mean range was verified as the major bradykinesia parameter (key indicator). This study is helpful to those who want to use consumer-grade inertial sensors for quantitative assessment of motor symptoms during treatment.

Quantitative Assessment of Parkinsonian Tremor Based on an Inertial Measurement Unit.

Quantitative assessment of parkinsonian tremor based on inertial sensors can provide reliable feedback on the effect of medication. In this regard, the features of parkinsonian tremor and its unique properties such as motor fluctuations and dyskinesia are taken into account. Least-square-estimation models are used to assess the severities of rest, postural, and action tremors. In addition, a time-frequency signal analysis algorithm for tremor state detection was also included in the tremor assessment method. This inertial sensor-based method was verified through comparison with an electromagnetic motion tracking system. Seven Parkinson's disease (PD) patients were tested using this tremor assessment system. The measured tremor amplitudes correlated well with the judgments of a neurologist (r = 0.98). The systematic analysis of sensor-based tremor quantification and the corresponding experiments could be of great help in monitoring the severity of parkinsonian tremor.

Design of topology optimized compliant legs for bio-inspired quadruped robots.

Robotic legs are an important component of the quadruped robot for achieving different motion gaits. Although the conventional rigid-link-based legs can generally perform robust motions, they still have the issues with poor sealing when operating in complex and liquid terrains. To cope with this problem, fully compliant legs with monolithic structure have been introduced in recent years to improve the system compactness and structural compliance of quadruped robots. In this article, we present a topology-optimization-based method to achieve efficient design of compliant robotic legs. In order to balance the structural stiffness and bending flexibility of the realized leg, a multi-objective optimization algorithm is utilized. A series of design cases are presented to illustrate the design principle and analytical procedure of the proposed method. In addition, experimental evaluation is also performed, and the results have demonstrated that, a quadruped robot with the optimized legs can successfully achieve stable and continuous straight-line walking motions.

Concept and first Implementation of an intracochlearly navigated Electrode Array for Cochlear Implantation.

Cochlear implants (CI) are an established treatment for people with deafness or severe hearing loss. To restore patients' hearing an electrode array (EA) of the CI is inserted into the cochlea to stimulate the auditory nerve. Thereby, the exact positioning and gentle insertion of the EA is crucial for optimal hearing perception outcome. Currently, only microscopic vision is available for entering the cochlea, but the critical intracochlear process during EA insertion is like a "black box" and the surgeon has to rely on haptic feedback. Methods for visualizing the insertion process during surgery are inaccurate or not suitable for routine use due to radiation exposure. To address this problem, we developed a computer-assisted and image-guided cochlear implantation system with an exact real-time visualization of the EA position during the insertion process. The system is based on an electromagnetic tracking system that measures the position and orientation of a sensor integrated into the tip of a EA prototype and visualizes it in presurgical image data. A first experiment with our system showed that a EA prototype could be inserted into a cochlea of a human temporal bone and placed with an accuracy of [Formula: see text]. A maximum insertion angle of 120° was achieved.

Design of Bionic Prosthetic Fingers Using 3D Topology Optimization.

Compliant mechanisms are frequently used in the design of prosthetic fingers since their monolithic structure and flexible movement are quite similar to the biological human fingers. However, the design of compliant prosthetic fingers is not easy, as the conventional rigid-link-based mechanism theory cannot be directly applied. In this paper, we introduce a 3D topology optimization based design framework to simplify the synthesis process of bionic compliant prosthetic fingers. The proposed framework is implemented in the software MATLAB and the realized fingers can be quickly fabricated using selective laser sintering (SLS) technology. To illustrate the design process of the proposed framework, a design example was presented. The bending performance of the realized finger was successfully verified by the FEM-based simulation and the payload test. In future work, the optimized fingers have the potential to be integrated into prosthetic hands to realize sophisticated grasping movements.

Cruciate-Ligament-Inspired Compliant Joints: Application to 3D-Printed Continuum Surgical Robots.

The rapid development of additive manufacturing technology makes it possible to fabricate a patient-specific surgical robot in a short time. To simplify the assembly process of the printed robotic system, compliant-joint-based monolithic structures are often used as substitutes for rigid-link mechanisms to realize flexible bending. In this paper, we introduce a cruciate-ligament-inspired compliant joint (CLCJ) to improve the bending stability of the 3D-printed continuum surgical robots. The basic structure of the tendon-driven CLCJ mechanism and its kinematic model were described in detail. The bending performance of CLCJ was also successfully evaluated by FEM simulation and experimental tests. Besides, a prototype of CLCJ-based surgical robotic system was presented to demonstrate its application in 3D-printed continuum surgical robots.

Design of a novel tendon-driven manipulator structure based on monolithic compliant rolling-contact joint for minimally invasive surgery.

PURPOSE: Compliant mechanisms are commonly used in the design of manipulator and surgical robotic tools for minimally invasive surgery (MIS) thanks to their compactness, ability of miniaturization and lower part count. However, conventional compliant joint has higher internal stiffness, which limits the bending radius. To overcome this problem, a novel tendon-driven manipulator structure based on monolithic compliant rolling-contact joint (CRCJ) is proposed. METHODS: The proposed rolling-contact mechanism is used to prevent cable slack during actuation, which occurs in conventional compliant joint design. By means of selective laser sintering (SLS) technique, the CRCJ can be fabricated in a monolithic structure, thus granting the CRCJ both the advantages of compliant joints and rolling-contact mechanism. Simulations with nonlinear finite element analysis (FEA) and experiments were conducted to evaluate and compare the mechanical properties of the proposed CRCJ with conventional leaf-type compliant joint including the bending and compliant motion. RESULTS: Experimental results showed that the CRCJ has lower bending stiffness, higher maximum bending angle (over [Formula: see text]) and a higher compliance compared to conventional compliant hinges, which allows a larger workspace and reduces the possibility of tissue injury. Agreement was also found between the nonlinear FEA and experiments regarding the relation between actuation force and bending angle. A primary prototype of a 3-DOF handheld laparoscopic manipulator with a diameter of 7 mm was further developed. CONCLUSION: A dexterous tendon-driven monolithic manipulator structure based on CRCJ for MIS is proposed. A preliminary prototype of a handheld laparoscopic manipulator demonstrates the capability of the CRCJ for steerable medical devices. However, design improvements based on FEA and application-orientated prototypes considering anatomical requirements still show room for improvements.

Evaluation of improved bi-manual endoscopic resection using a customizable 3D-printed manipulator system designed for use with standard endoscopes: a feasibility study using a porcine ex-vivo model.

Background and study aims A major drawback of endoscopic en-bloc resection technique is its inability to perform bimanual tasks. Although endoscopic platforms that enable bimanual tasks are commercially available, they are neither approved for various locations nor adaptable to specific patients and indications. Methods Based on evolution of an adaptive 3D-printable platform concept, system variants with different characteristic properties were evaluated for ESD scenarios, ex-vivo in two locations in the stomach and colorectum. Results In total 28 ESDs were performed (7 antrum, 7 corpus in inversion, 7 cecum, 7 rectum) in a porcine ex-vivo setup. ESD was feasible in 21 cases. Investigated manipulator variants are differently well suited for performing ESD within the varying interventions scenarios. Dual-arm manipulators allowed autonomous ESD, while single-arm flexible manipulators could be used more universally due to their compact design, especially for lesions difficult to access. Pediatric scopes were too frail to guide the overtube-manipulators in extremely angled positions. Working in the rectum was impaired using long-sized manipulator arms. Conclusions The presented endoscopic platform based on 3D-printable and customizable manipulator structures might be a promising approach for future improvement of ESD procedure. With regard to localization, especially flexible manipulators attached to standard endoscopes appear to be most promising for further application of specific and individualised manipulator systems.

Bone treatment laser-navigated surgery.

A new concept was developed based on the experience gained in dental rehabilitation with implantation in the oral maxillofacial region. Despite the use of cooling systems, mechanically rotating instruments may damage the surrounding tissue due to the frictional heat generated. An alternative approach for bone removal is laser application. A preoperative plan was prepared. Laser ablation was performed in accordance with the data set on bovine bone using a navigation system. This new concept allows precise bone removal and adjustment of the laser power according to the preoperative plan. The power of the laser automatically decreases as it approaches the border of the planned cavity or important anatomical structures. The advantage of this approach is precise and safe bone removal without damaging the bone by frictional heat.

Bionic Design of a Disposable Compliant Surgical Forceps With Optimized Clamping Performance.

Disposable forceps are frequently used in different surgical procedures to prevent infections caused by poorly sterilized reusable metal forceps. Compared to traditional rigid-joint mechanisms, compliant mechanisms are much easier to sterilize due to their monolithic structure, hence they are widely used for designing disposable surgical forceps. However, the clamping performance of plastic compliant forceps is generally less robust than metal forceps, which has greatly limited their use in medical applications. To cope with this problem, a novel 3D-printed plastic compliant forceps with optimized clamping performance was developed in this paper for open surgery and physical nursing applications. Bio-inspired topology optimization techniques were employed to synthesize the forceps. The clamping capability of the proposed forceps was evaluated by finite element analysis and loading tests. Results showed that the proposed forceps can generate greater and more stable clamping forces than the previous model of disposable compliant forceps. The proposed bionic optimization method also has potential for synthesizing compliant devices for robotic surgery.

Patient-Specific Instrument with a Cutting Template for Mitral Valve Repair by Resection.

Mitral valve regurgitation is one of the most common heart valve diseases and mitral valve repair is the favored therapy, in which a part of the mitral valve is resected. To improve preoperative planning of this challenging surgery, patient-specific mitral valve replicas have been developed on which the repair can be simulated. However, there is no possibility yet to transfer the planning from the replica to the surgery of the patient. To solve this problem, we developed a patient-specific instrument with a cutting template, intraoperatively visualizing the part of the mitral valve to be resected as planned on the replica. To realize this instrument, the surgeon first simulates mitral valve repair by resection on a patient-specific mitral valve replica. This postoperative mitral valve replica is then digitalized and from it and a preoperative mitral valve model the instrument with cutting template is automatically designed and then 3D printed. An expert heart surgeon successfully tested the functional principle of the instrument on a pig mitral valve.

Design and development of the efficient anguilliform swimming robot- MAR.

Propulsion of swimming robots at the surface and underwater is largely dominated by rotary propellers due to high thrust, but at the cost of low efficiency. Due to their inherently high speed turning motion, sharp propeller blades and generated noise, they also present a disturbance to maritime ecosystems. Our work presents a bio-inspired approach to efficient and eco-friendly swimming with moderate to high thrust. This paper describes the concept, development and experimental validation of the novel anguilliform robot MAR. With 15 elements making up the 0.5 m long propulsive section and driven by a single, speed-controlled brushless DC motor (BLDC), the robot creates a smooth continuous traveling wave for propulsion. Steering and autonomy are realized by an actuated head with integrated batteries that serves as a front-rudder. Almost neutral buoyancy paired with individually actuated pectoral fins furthermore enable submerged swimming and diving maneuvers. MAR accomplished high thrusts at a moderate power consumption in first performance tests. The achieved maximum velocity and the speed related efficiency (defined as the achieved speed over the power consumption m Ws-1) did not fulfill the expectations in the first tests (in comparison to commercial rotary thrusters), which can be largely attributed to the spatial limitations and an imperfect test setup. Nevertheless, the potential towards highly efficient and high thrust propulsion is visible and will be further investigated in future efforts.

A handheld flexible manipulator system for frontal sinus surgery.

PURPOSE: Draf drainage is the standard treatment procedure for frontal sinus diseases. In this procedure, rigid angled endoscopes and rigid curved instruments are used. However, laterally located pathologies in the frontal sinus cannot be reached with rigid instrumentation. In order to assist surgeons with such complicated cases, we propose a novel handheld flexible manipulator system. METHODS: A cross section of 3 mm × 4.6 mm enables transnasal guiding of a flexible endoscope with 1.4 mm diameter and a standard flexible surgical instrument with up to 1.8 mm diameter into the frontal sinus with increased reachability. The developed system consists of an electrical discharge-machined flexure hinge-based nitinol manipulator arm and a purely mechanical handheld control unit. The corresponding control unit enables upward and left-right bending of the manipulator arm, translation, rolling, actuation and also quick exchange of the surgical instrument. In order to verify the fulfillment of performance requirements, tests regarding reachability and payload capacity were conducted. RESULTS: Reachability tests showed that the manipulator arm can be inserted into the frontal sinus and reach its lateral regions following a Draf IIa procedure. The system can exert forces of at least 2 N in the vertical direction and 1 N in the lateral direction which is sufficient for manipulation of frontal sinus pathologies. CONCLUSION: Considering the fact that the anatomical requirements of the frontal sinus are not addressed satisfactorily in the development of prospective flexible instruments, the proposed system shows great potential in terms of therapeutic use owing to its small cross section and dexterity.

Evaluation of long-term stability of monolithic 3D-printed robotic manipulator structures for minimally invasive surgery.

PURPOSE: In the era of patient-centered medicine, clinical procedures, tools and instruments should be individually adapted to the patient. In this context, the presented 3D-printed Single-Port Overtube Manipulator System follows the aims to provide patient- and task-specific disposable manipulators for minimally invasive surgery. In a first experiment, the robustness of the monolithic flexure hinge structures in use as robotic manipulators will be investigated. METHODS: Customizable monolithic manipulator structures designed by means of an automated design process and manufactured with selective laser sintering were investigated with regard to long-term stability in an endurance test. Therefore, a bare manipulator arm, an arm equipped with a standard instrument and finally loaded with an additional load of 0.5 N were evaluated by continuously following a trajectory within the workspace of the manipulator arms over a period of 90 min. RESULTS: The unloaded manipulator as well as the manipulator arm equipped with a standard instrument showed a sufficient reproducibility (deviation of 1.5 mm and 2.5 mm, respectively, on average) with regard to an application as telemanipulated master-slave surgical robotic system. The 3D-printed manipulators showed no damage and maintained integrity after the experiment. CONCLUSION: It has been shown that 3D-printed manipulators in principle are suitable for use as disposable surgical manipulator systems and offer a long-term stability over at least 90 min. The developed manipulator design shows great potential for the production of patient-, task- and user-specific robot systems. However, the manipulator geometries as well as the control strategies still show room for improvements.

How to operate a liver tumor you cannot see.

BACKGROUND: As recent chemotherapy regimens for metastatic colorectal cancer become more and more effective in a neoadjuvant setting before liver surgery, a "complete" clinical response is sometimes documented on imaging. Without operation though, metastatic recurrence is likely to commence within 12 months. Surgeons now face the problem to resect non-visualizable and non-palpable lesions. METHODS: Computer-based virtual surgery planning can be used to fuse pre- and postchemotherapy computed tomography data to develop an operative strategy. This information is then intraoperatively transferred to the liver surface using an image-guided stereotactically navigated ultrasound dissector. This enables the surgeon to perform a resection that is otherwise not possible. RESULTS: During operation, detection of the lesion through palpation or ultrasound was impossible. After registering the virtual operation plan into the navigation system, the planned resection was performed without problems. Histopathologic workup showed vital tumor cells in the specimen. CONCLUSION: The new image-guided stereotactic navigation technique combined with virtual surgery planning can solve the surgeon's dilemma and yield a successful operation.

Anatomical Characterization of Frontal Sinus and Development of Representative Models.

This paper presents the methods and the materials towards characterizing frontal sinus anatomy and developing representative anatomical models which reflect the variance of the anatomy with three different sizes: small, medium and large. Anatomical characterization was performed using computer tomography data of up to 50 anonymous patients. Dimensional and volumetric measurements were conducted using the .stl files generated by segmentation and 3-D reconstruction. Three representative data sets were chosen to be realized in the form of models with frontal sinuses of small, medium and large sizes. The models include bone, mucosa and skin structures, whereas bone structures were manufactured by selective laser sintering of polyamide and the soft tissues by casting of gelatin and silicone. To ensure realistic optical and mechanical properties of the mucosa, verification tests were performed and the results were integrated into the manufacturing process.

First clinical application of a navigation-controlled shaver in paranasal sinus surgery.

Conventional, pointer-based navigated Functional Endoscopic Sinus Surgery (FESS) has been shown to have certain limitations: necessity of instrument change for navigation, changes in the surgeon's line-of-sight axis, and limited length of use of the navigation information. These limitations result in negative consequences regarding the surgeon's attentiveness in any given situation, as well as in his cognitive work-load. The principle of Navigated Control offers advantages concerning these problems and limitations of the conventionally navigated FESS. This Chapter analyzes the first clinical deployment of a navigation-controlled shaver in FESS on the basis of the following questions: (1) Is clinical deployment of the navigation-controlled shaver possible with the pre-clinic evaluated set-up? (2) What information relevant to the surgery is relayed in an intraoperative setting by the navigation-controlled shaver? (3) How does deployment of the navigation-controlled shaver affect the ergonomics of the surgery? Ten patients with chronic sinusitis ethmoidalis were included in the study (average age: 48 [22-71], m:w=4:6). The preoperative and intraoperative workflow was documented according to the Innovation Center Computer Assisted Surgery (ICCAS) Workflow protocol. Data regarding the surgical validity of the information and ergonomic characteristics were recorded by means of questionnaires. The average time required for segmentation of the workspace was 14.2 minutes. The shaver switched off through Navigated Control an average 16.5 times during an FESS. From this amount, five shutdowns on average were initiative and six were determined to be provoked. The shutdowns were indicated by the operators to be correct in 199 of 220 (90.5%) events and in agreement with the actual position and planned resection borders. The quality of the relayed navigation information was indicated with an average Level of Quality (LOQ) of 56.4 [50-80]. The most favorable evaluation was attained for navigation in the area of the sphenoid sinus with 71 points on average [60-80]. During an FESS, the navigation information led to a change in the planned surgical strategy an average of 0.9 [0-3] times. Throughout all surgical procedures, the situation awareness was assessed an average of 2.7 points better than with the conventionally navigated FESS. This also was the case for the cognitive workload (Workload shift) with 2.8 [1-3.5] points. This Chapter proves the clinical applicability of a navigation-controlled instrument by means of a shaver in Ears, Nose, and Throat (ENT) surgery for the first time. Reproduction of the dental splint registration, manual segmentation of the working space, and attachment of the registration star still prove to be critical aspects. Data regarding quality of the information relayed by the navigation system and resulting change in surgical strategy lead to the conclusion that the authors are dealing with, in the overall evaluation, supplementary and surgically relevant information. This information is more efficiently transferred to the surgeon by means of Navigated Control that allows, according to the following results, both an improved understanding of the information and cognitive easing of stress for the surgeon.

Virtual endoscopy on a portable navigation system for ENT surgery.

Virtual endoscopy is considered as an ideal aid assessing the complex anatomy of patients and has already been evaluated in several clinical studies. However, due to the increasing quality of modern CT- and MRT-images, present virtual-endoscopy software relies on powerful hardware. In this contribution virtual endoscopy on a portable navigation system for ENT surgery is proposed. The portable navigation system features a tablet pc to ensure a device that does not need much space in the operating room.

Model for nerve visualization in preoperative image data based on intraoperatively gained EMG signals.

While removing bone tissue of the mastoid, the facial nerve is at risk of being injured. In this contribution a model for nerve visualization in preoperative image data based on intraoperatively gained EMG signals is proposed. A neuro monitor can assist the surgeon locating and preserving the nerve. With the proposed model gained EMG signals can be spatially related to the patient resp. the image data. During navigation the detected nerve course will be visualized and hence permanently available for assessing the situs.

Patient-specific catheter shaping for the minimally invasive closure of the left atrial appendage.

PURPOSE: The minimally invasive closure of the left atrial appendage is a promising alternative to anticoagulation for stroke prevention in patients suffering from atrial fibrillation. One of the challenges of this procedure is the correct positioning and the coaxial alignment of the tip of the catheter sheath to the implant landing zone. METHOD: In this paper, a novel preoperative planning system is proposed that allows patient-individual shaping of catheters to facilitate the correct positioning of the catheter sheath by offering a patient-specific catheter shape. Based on preoperative three-dimensional image data, anatomical points and the planned implant position are marked interactively and a patient-specific catheter shape is calculated if the standard catheter is not considered as suitable. An approach to calculate a catheter shape with four bends by maximization of the bending radii is presented. Shaping of the catheter is supported by a bending form that is automatically generated in the planning program and can be directly manufactured by using additive manufacturing methods. RESULTS: The feasibility of the planning and shaping of the catheter could be successfully shown using six data sets. The patient-specific catheters were tested in comparison with standard catheters by physicians on heart models. In four of the six tested models, the participating physicians rated the patient-individual catheters better than the standard catheter. CONCLUSION: The novel approach for preoperatively planned and shaped patient-specific catheters designed for the minimally invasive closure of the left atrial appendage could be successfully implemented and a feasibility test showed promising results in anatomies that are difficult to access with the standard catheter.