Robots and tools for remodeling bone

The field of robotic surgery has progressed from small teams of researchers repurposing industrial robots, to a competitive and highly innovative subsection of the medical device industry. Surgical robots allow surgeons to perform tasks with greater ease, accuracy, or safety, and fall under one of four levels of autonomy; active, semi-active, passive, and remote manipulator. The increased accuracy afforded by surgical robots has allowed for cementless hip arthroplasty, improved postoperative alignment following knee arthroplasty, and reduced duration of intraoperative fluoroscopy among other benefits. Cutting of bone has historically used tools such as hand saws and drills, with other elaborate cutting tools now used routinely to remodel bone. Improvements in cutting accuracy and additional options for safety and monitoring during surgery give robotic surgeries some advantages over conventional techniques. This article aims to provide an overview of current robots and tools with a common target tissue of bone, proposes a new process for defining the level of autonomy for a surgical robot, and examines future directions in robotic surgery

Medical robots with potential applications in participatory and opportunistic remote sensing: A review

Among numerous applications of medical robotics, this paper concentrates on the design, optimal use and maintenance of the related technologies in the context of healthcare, rehabilitation and assistive robotics, and provides a comprehensive review of the latest advancements in the foregoing field of science and technology, while extensively dealing with the possible applications of participatory and opportunistic mobile sensing in the aforementioned domains. The main motivation for the latter choice is the variety of such applications in the settings having partial contributions to functionalities such as artery, radiosurgery, neurosurgery and vascular intervention. From a broad perspective, the aforementioned applications can be realized via various strategies and devices benefiting from detachable drives, intelligent robots, human-centric sensing and computing, miniature and micro-robots. Throughout the paper tens of subjects, including sensor-fusion, kinematic, dynamic and 3D tissue models are discussed based on the existing literature on the state-of-the-art technologies. In addition, from a managerial perspective, topics such as safety monitoring, security, privacy and evolutionary optimization of the operational efficiency are reviewed

Augmented reality (AR) for surgical robotic and autonomous systems: State of the art, challenges, and solutions

Despite the substantial progress achieved in the development and integration of augmented reality (AR) in surgical robotic and autonomous systems (RAS), the center of focus in most devices remains on improving end-effector dexterity and precision, as well as improved access to minimally invasive surgeries. This paper aims to provide a systematic review of different types of state-of-the-art surgical robotic platforms while identifying areas for technological improvement. We associate specific control features, such as haptic feedback, sensory stimuli, and human-robot collaboration, with AR technology to perform complex surgical interventions for increased user perception of the augmented world. Current researchers in the field have, for long, faced innumerable issues with low accuracy in tool placement around complex trajectories, pose estimation, and difficulty in depth perception during two-dimensional medical imaging. A number of robots described in this review, such as Novarad and SpineAssist, are analyzed in terms of their hardware features, computer vision systems (such as deep learning algorithms), and the clinical relevance of the literature. We attempt to outline the shortcomings in current optimization algorithms for surgical robots (such as YOLO and LTSM) whilst providing mitigating solutions to internal tool-to-organ collision detection and image reconstruction. The accuracy of results in robot end-effector collisions and reduced occlusion remain promising within the scope of our research, validating the propositions made for the surgical clearance of ever-expanding AR technology in the future

The new old normal : reassessing perioperative oxygen consumption and haemodynamics in the elderly

Perioperative haemodynamic instability and disturbances of global oxygen transport are associated with complications and organ injury after surgery. The continuously growing population of elderly in surgical care are at higher risk due to age-related cardiovascular alterations and increased prevalence of comorbidities. Optimised and tailored haemodynamic interventions may improve outcomes, but goals to aim for and responses to expect are not adjusted for elderly. Hypotension and changes in oxygen consumption (VO2) induced by anaesthesia are potentially very relevant in the elderly and reassessment is needed in modern perioperative care with current methodologies. In this thesis, cardiac output and haemodynamic changes related to hypotension after spinal anaesthesia (SPA) are outlined in the first study. VO2 after general anaesthesia (GA) and surgery is investigated in three studies with different approaches; by meta-analysis, prospectively during major surgery and by method comparison. Study I (prospective observational): 20 ASA II-IV patients (mean age 72 years) were monitored with LiDCO™plus prior to and 45 minutes after injection of SPA. Stroke volume and cardiac index, and consequently oxygen delivery index, decreased before the intrathecal injection and this decrease progressed after SPA in those who developed hypotension. In contrast, the non-hypotensive demonstrated an initial increase in cardiac index after SPA. Logistic regression analyses demonstrated that pre-anaesthetic changes of cardiac index could predict post-spinal hypotension (OR 0.79, 95% CI: 0.60, 0.91) with high discriminative ability (AUC 0.91). Study II (systematic review and meta-analysis): Cochrane Library, MEDLINE and EMBASE databases were searched for studies with measurements of VO2 before and after induction of GA. 24 studies with 453 patients were identified, published 1969-2000. Cochrane and NIH quality assessment tools revealed general high risk of bias in the majority of studies. However, measurements and interventions were described in great detail. A random-effects meta-analysis estimated the reduction of VO2 to -33 (95% CI: -38, -28) ml min-1 m-2 during GA but with uncertainty of the estimate due to very low quality as indicated in a GRADE evidence profile. A sample size calculation for study III was performed based on this data. Study III (prospective observational): VO2 was measured by indirect calorimetry (QuarkRMR), before, during and after major upper abdominal surgery in 20 ASA II-IV patients (mean age 73 years). VO2 decreased by a mean of -46 (95% CI: -55, -38) ml min-1 m-2 after induction of GA and increased during surgery. Simultaneous calculations of oxygen delivery (DO2) and estimated oxygen extraction ratio (O2ER) from LiDCO™plus monitoring and arterial-central venous blood gas content showed low intraoperative levels of extraction and delivery. Mixed effect models of relative changes of intraoperative VO2 compared to DO2 and estimated O2ER indicated that these parameters changed in parallel. Study IV (method comparison): Estimations of VO2 by LiDCO™plus-derived cardiac output and arterial-central venous oxygen content difference were compared to 85 simultaneous measurements by indirect calorimetry from study III. Intraclass correlation, Bland-Altman and mixed models analyses for relative changes over time indicated systematic underestimation and poor absolute agreement by this method compared to indirect calorimetry. It may be possible to construct methods for estimation or trending of VO2 from routine monitoring, but further adjustments and assessment in larger populations are needed. In summary, these studies characterise and demonstrate that peri-anaesthetic cardiac output and oxygen consumption undergo changes in elderly patients important to haemodynamic stability and oxygen transport. Mechanistic approaches, with feasible and reliable methods for monitoring or estimation of these changes, are suggested when investigating haemodynamic interventions in elderly

Impact of Ear Occlusion on In-Ear Sounds Generated by Intra-oral Behaviors

We conducted a case study with one volunteer and a recording setup to detect sounds induced by the actions: jaw clenching, tooth grinding, reading, eating, and drinking. The setup consisted of two in-ear microphones, where the left ear was semi-occluded with a commercially available earpiece and the right ear was occluded with a mouldable silicon ear piece. Investigations in the time and frequency domains demonstrated that for behaviors such as eating, tooth grinding, and reading, sounds could be recorded with both sensors. For jaw clenching, however, occluding the ear with a mouldable piece was necessary to enable its detection. This can be attributed to the fact that the mouldable ear piece sealed the ear canal and isolated it from the environment, resulting in a detectable change in pressure. In conclusion, our work suggests that detecting behaviors such as eating, grinding, reading with a semi-occluded ear is possible, whereas, behaviors such as clenching require the complete occlusion of the ear if the activity should be easily detectable. Nevertheless, the latter approach may limit real-world applicability because it hinders the hearing capabilities.</p

IMPROVING VENTRICULAR CATHETER DESIGN THROUGH COMPUTATIONAL FLUID DYNAMICS

Cerebrospinal fluid (CSF) shunts are fully implantable medical devices that are used to treat patients suffering from conditions characterized by elevated intracranial pressure, such as hydrocephalus. In cases of shunt failure or malfunction, patients are often required to endure one or more revision surgeries to replace all or part of the shunt. One of the primary causes of CSF shunt failure is obstruction of the ventricular catheter, a component of the shunt system implanted directly into the brain\u27s ventricular system. This work aims to improve the design of ventricular catheters in order to reduce the incidence of catheter obstruction and thereby reduce overall shunt failure rates. Modern CSF shunts are the result of six decades of neurosurgical progress; however, in spite of revolutionary advances in engineering, the ventricular catheter remains largely unchanged in its functionality and performance from its original design. A thorough review of the history of ventricular catheter design, and the contemporary efforts to improve it, have given valuable insight into the challenges still remaining. One of the challenges is to better understand shunt flow in order to improve the flow performance of ventricular catheters. To characterize CSF flow through catheters, this work integrated computational fluid dynamics (CFD) modelling with experimental validation. A fully-parametrized, 3-dimensional CFD catheter model was developed that allowed for exploration of the geometric design features key to the catheter’s fluid dynamics. The model was validated using bench tests and advanced fluid imaging techniques, including positron emission particle tracking (PEPT). Once validated, the model served as a basis for automated, iterative parametric studies to be conducted. This involved creating a coupled framework between the CFD simulations and a parametric analysis toolkit. Sensitivity analyses and optimization studies were performed with the objective of improving catheter flow patterns. By simulating thousands of possible geometric catheter designs, much insight was gathered that can provide practical guidelines for producing optimal flow through ventricular catheters. Ultimately, those insights can lead to better quality of life for patients who require shunts, by reducing ventricular catheter obstruction rates and the need for revision surgeries

Virtual Reality Aided Mobile C-arm Positioning for Image-Guided Surgery

Image-guided surgery (IGS) is the minimally invasive procedure based on the pre-operative volume in conjunction with intra-operative X-ray images which are commonly captured by mobile C-arms for the confirmation of surgical outcomes. Although currently some commercial navigation systems are employed, one critical issue of such systems is the neglect regarding the radiation exposure to the patient and surgeons. In practice, when one surgical stage is finished, several X-ray images have to be acquired repeatedly by the mobile C-arm to obtain the desired image. Excessive radiation exposure may increase the risk of some complications. Therefore, it is necessary to develop a positioning system for mobile C-arms, and achieve one-time imaging to avoid the additional radiation exposure. In this dissertation, a mobile C-arm positioning system is proposed with the aid of virtual reality (VR). The surface model of patient is reconstructed by a camera mounted on the mobile C-arm. A novel registration method is proposed to align this model and pre-operative volume based on a tracker, so that surgeons can visualize the hidden anatomy directly from the outside view and determine a reference pose of C-arm. Considering the congested operating room, the C-arm is modeled as manipulator with a movable base to maneuver the image intensifier to the desired pose. In the registration procedure above, intensity-based 2D/3D registration is used to transform the pre-operative volume into the coordinate system of tracker. Although it provides a high accuracy, the small capture range hinders its clinical use due to the initial guess. To address such problem, a robust and fast initialization method is proposed based on the automatic tracking based initialization and multi-resolution estimation in frequency domain. This hardware-software integrated approach provides almost optimal transformation parameters for intensity-based registration. To determine the pose of mobile C-arm, high-quality visualization is necessary to locate the pathology in the hidden anatomy. A novel dimensionality reduction method based on sparse representation is proposed for the design of multi-dimensional transfer function in direct volume rendering. It not only achieves the similar performance to the conventional methods, but also owns the capability to deal with the large data sets

In Vitro Biomechanical Testing and Computational: Modeling in Spine

Two separate in vitro biomechanical studies were conducted on human cadaveric spines (Lumbar) to evaluate the stability following the implantation of two different spinal fixation devices interspinous fixation device (ISD) and Hybrid dynamic stabilizers. ISD was evaluated as a stand-alone and in combination with unilateral pedicle rod system. The results were compared against the gold standard, spinal fusion (bilateral pedicle rod system). The second study involving the hybrid dynamic system, evaluated the effect on adjacent levels using a hybrid testing protocol. A robotic spine testing system was used to conduct the biomechanical tests. This system has the ability to apply continuous unconstrained pure moments while dynamically optimizing the motion path to minimize off-axis loads during testing. Thus enabling precise control over the loading and boundary conditions of the test. This ensures test reliability and reproducibility. We found that in flexion-extension, the ISD can provide lumbar stability comparable to spinal fusion. However, it provides minimal rigidity in lateral bending and axial rotation when used as a stand-alone. The ISD with a unilateral pedicle rod system when compared to the spinal fusion construct were shown to provide similar levels of stability in all directions, though the spinal fusion construct showed a trend toward improved stiffness overall. The results for the dynamic stabilization system showed stability characteristics similar to a solid all metal construct. Its addition to the supra adjacent level (L3- L4) to the fusion (L4- L5) indeed protected the adjacent level from excessive motion. However, it essentially transformed a 1 level into a 2 level lumbar fusion with exponential transfer of motion to the fewer remaining discs (excessive adjacent level motion). The computational aspect of the study involved the development of a spine model (single segment). The kinematic data from these biomechanical studies (ISD study) was then used to validate a finite element model

Augmented navigation

Spinal fixation procedures have the inherent risk of causing damage to vulnerable anatomical structures such as the spinal cord, nerve roots, and blood vessels. To prevent complications, several technological aids have been introduced. Surgical navigation is the most widely used, and guides the surgeon by providing the position of the surgical instruments and implants in relation to the patient anatomy based on radiographic images. Navigation can be extended by the addition of a robotic arm to replace the surgeon’s hand to increase accuracy. Another line of surgical aids is tissue sensing equipment, that recognizes different tissue types and provides a warning system built into surgical instruments. All these technologies are under continuous development and the optimal solution is yet to be found. The aim of this thesis was to study the use of Augmented Reality (AR), Virtual Reality (VR), Artificial Intelligence (AI), and tissue sensing technology in spinal navigation to improve precision and prevent surgical errors. The aim of Paper I was to develop and validate an algorithm for automatizing the intraoperative planning of pedicle screws. An AI algorithm for automatic segmentation of the spine, and screw path suggestion was developed and evaluated. In a clinical study of advanced deformity cases, the algorithm could provide correct suggestions for 86% of all pedicles—or 95%, when cases with extremely altered anatomy were excluded. Paper II evaluated the accuracy of pedicle screw placement using a novel augmented reality surgical navigation (ARSN) system, harboring the above-developed algorithm. Twenty consecutively enrolled patients, eligible for deformity correction surgery in the thoracolumbar region, were operated on using the ARSN system. In this cohort, we found a pedicle screw placement accuracy of 94%, as measured according to the Gertzbein grading scale. The primary goal of Paper III was to validate an extension of the ARSN system for placing pedicle screws using instrument tracking and VR. In a porcine cadaver model, it was demonstrated that VR instrument tracking could successfully be integrated with the ARSN system, resulting in pedicle devices placed within 1.7 ± 1.0 mm of the planed path. Paper IV examined the feasibility of a robot-guided system for semi-automated, minimally invasive, pedicle screw placement in a cadaveric model. Using the robotic arm, pedicle devices were placed within 0.94 ± 0.59 mm of the planned path. The use of a semi-automated surgical robot was feasible, providing a higher technical accuracy compared to non-robotic solutions. Paper V investigated the use of a tissue sensing technology, diffuse reflectance spectroscopy (DRS), for detecting the cortical bone boundary in vertebrae during pedicle screw insertions. The technology could accurately differentiate between cancellous and cortical bone and warn the surgeon before a cortical breach. Using machine learning models, the technology demonstrated a sensitivity of 98% [range: 94-100%] and a specificity of 98% [range: 91-100%]. In conclusion, several technological aids can be used to improve accuracy during spinal fixation procedures. In this thesis, the advantages of adding AR, VR, AI and tissue sensing technology to conventional navigation solutions were studied

SMART IMAGE-GUIDED NEEDLE INSERTION FOR TISSUE BIOPSY

M.S