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.Web of Science1923art. no. 519

Virtual reality training and assessment in laparoscopic rectum surgery

Background: Virtual-reality (VR) based simulation techniques offer an efficient and low cost alternative to conventional surgery training. This article describes a VR training and assessment system in laparoscopic rectum surgery. Methods: To give a realistic visual performance of interaction between membrane tissue and surgery tools, a generalized cylinder based collision detection and a multi-layer mass-spring model are presented. A dynamic assessment model is also designed for hierarchy training evaluation. Results: With this simulator, trainees can operate on the virtual rectum with both visual and haptic sensation feedback simultaneously. The system also offers surgeons instructions in real time when improper manipulation happens. The simulator has been tested and evaluated by ten subjects. Conclusions: This prototype system has been verified by colorectal surgeons through a pilot study. They believe the visual performance and the tactile feedback are realistic. It exhibits the potential to effectively improve the surgical skills of trainee surgeons and significantly shorten their learning curve. © 2014 John Wiley & Sons, Ltd

Advances in FAI Imaging: a Focused Review

Purpose of review: Femoroacetabular impingement (FAI) is one of the main causes of hip pain in young adults and poses clinical challenges which have placed it at the forefront of imaging and orthopedics. Diagnostic hip imaging has dramatically changed in the past years, with the arrival of new imaging techniques and the development of magnetic resonance imaging (MRI). This article reviews the current state-of-the-art clinical routine of individuals with suspected FAI, limitations, and future directions that show promise in the field of musculoskeletal research and are likely to reshape hip imaging in the coming years. Recent findings: The largely unknown natural disease course, especially in hips with FAI syndrome and those with asymptomatic abnormal morphologies, continues to be a problem as far as diagnosis, treatment, and prognosis are concerned. There has been a paradigm shift in recent years from bone and soft tissue morphological analysis towards the tentative development of quantitative approaches, biochemical cartilage evaluation, dynamic assessment techniques and, finally, integration of artificial intelligence (AI)/deep learning systems. Imaging, AI, and hip preserving care will continue to evolve with new problems and greater challenges. The increasing number of analytic parameters describing the hip joint, as well as new sophisticated MRI and imaging analysis, have carried practitioners beyond simplistic classifications. Reliable evidence-based guidelines, beyond differentiation into pure instability or impingement, are paramount to refine the diagnostic algorithm and define treatment indications and prognosis. Nevertheless, the boundaries of morphological, functional, and AI-aided hip assessment are gradually being pushed to new frontiers as the role of musculoskeletal imaging is rapidly evolving.info:eu-repo/semantics/publishedVersio

Multi-body simulation of a canine hind limb: model development, experimental validation and calculation of ground reaction forces

<p>Abstract</p> <p>Background</p> <p>Among other causes the long-term result of hip prostheses in dogs is determined by aseptic loosening. A prevention of prosthesis complications can be achieved by an optimization of the tribological system which finally results in improved implant duration. In this context a computerized model for the calculation of hip joint loadings during different motions would be of benefit. In a first step in the development of such an inverse dynamic multi-body simulation (MBS-) model we here present the setup of a canine hind limb model applicable for the calculation of ground reaction forces.</p> <p>Methods</p> <p>The anatomical geometries of the MBS-model have been established using computer tomography- (CT-) and magnetic resonance imaging- (MRI-) data. The CT-data were collected from the pelvis, femora, tibiae and pads of a mixed-breed adult dog. Geometric information about 22 muscles of the pelvic extremity of 4 mixed-breed adult dogs was determined using MRI. Kinematic and kinetic data obtained by motion analysis of a clinically healthy dog during a gait cycle (1 m/s) on an instrumented treadmill were used to drive the model in the multi-body simulation.</p> <p>Results and Discussion</p> <p>As a result the vertical ground reaction forces (z-direction) calculated by the MBS-system show a maximum deviation of 1.75%BW for the left and 4.65%BW for the right hind limb from the treadmill measurements. The calculated peak ground reaction forces in z- and y-direction were found to be comparable to the treadmill measurements, whereas the curve characteristics of the forces in y-direction were not in complete alignment.</p> <p>Conclusion</p> <p>In conclusion, it could be demonstrated that the developed MBS-model is suitable for simulating ground reaction forces of dogs during walking. In forthcoming investigations the model will be developed further for the calculation of forces and moments acting on the hip joint during different movements, which can be of help in context with the <it>in silico </it>development and testing of hip prostheses.</p

A Feasibility Study of Ultra-Short Echo Time MRI for Positive Contrast Visualization of Prostate Brachytherapy Permanent Seed Implants for Post-Implant Dosimetry

Purpose: Ultra-short echo time (UTE) imaging is a magnetic resonance imaging (MRI) technique that uses very short echo times (on the order of microseconds) to measure rapid T2 relaxation. An application of UTE is the visualization of magnetic susceptibility-induced shortening of T2 in tissues adjacent to metal, such as prostate tissue with implanted brachytherapy seeds. This study assessed UTE imaging of prostate brachytherapy seeds on a clinical 3T MRI scanner to provide images for post-implant dosimetry. Methods: A prostate tissue phantom was made of gelatin mixed with Gd and other materials to mimic the prostate peripheral zone’s T1 and T2 relaxation times; this phantom was used to investigate the effect of UTE acquisition parameters on brachytherapy seed visibility. A second phantom was made to model prostate tissue surrounded by muscle tissue; this pelvic phantom was implanted with 85 titanium brachytherapy seeds (STM1251, Bard Medical). Both phantoms were scanned on a 3T GE scanner with a 3D UTE pulse sequence and a fast spin echo (FSE) pulse sequence. The average seed SNR, the CNR between seed and prostate material, and visual characteristics of the seeds were assessed. A seed counting procedure was developed based on the visual seed characteristics, and subsequently used by two physicists to locate seeds in UTE images of the pelvic phantom. Results: On 3D UTE images, the metal seeds caused a bright ring-link artifact in adjacent prostate tissue due to susceptibility-induced T2 shortening. The average seed SNR was 15.99±1.52 for UTE compared to 32.32±22.43 for FSE; CNR between seed and prostate was 6.73±1.85 for UTE vs. 23.76±12.87 for FSE. The ring was larger in diameter than a seed itself; apparent seed diameters were 4.65±0.363 mm for UTE compared to 1.46±0.38 mm for FSE. The 3D spatial ring pattern facilitated differentiation of seeds from needle tracks and seed spacers. The two physicists counted 83 and 86 seeds respectively in the UTE images. Prostate boundaries were less well visualized with UTE compared to FSE. Conclusion: With its ability to visualize brachytherapy seeds, UTE imaging appears to provide an alternative approach to CT for seed identification. Compared to fusion of separately-acquired CT images and T2-weighted MR images (for delineation of prostate boundaries), UTE and T2-weighted MR can be acquired in a single imaging session – a convenience to patients while potentially minimizing inter-modality image registration issues. A study in prostate brachytherapy patients of the quality of post-implant dosimetry with UTE imaging compared to CT imaging is recommended

Segmentation of pelvic structures from preoperative images for surgical planning and guidance

Prostate cancer is one of the most frequently diagnosed malignancies globally and the second leading cause of cancer-related mortality in males in the developed world. In recent decades, many techniques have been proposed for prostate cancer diagnosis and treatment. With the development of imaging technologies such as CT and MRI, image-guided procedures have become increasingly important as a means to improve clinical outcomes. Analysis of the preoperative images and construction of 3D models prior to treatment would help doctors to better localize and visualize the structures of interest, plan the procedure, diagnose disease and guide the surgery or therapy. This requires efficient and robust medical image analysis and segmentation technologies to be developed. The thesis mainly focuses on the development of segmentation techniques in pelvic MRI for image-guided robotic-assisted laparoscopic radical prostatectomy and external-beam radiation therapy. A fully automated multi-atlas framework is proposed for bony pelvis segmentation in MRI, using the guidance of MRI AE-SDM. With the guidance of the AE-SDM, a multi-atlas segmentation algorithm is used to delineate the bony pelvis in a new \ac{MRI} where there is no CT available. The proposed technique outperforms state-of-the-art algorithms for MRI bony pelvis segmentation. With the SDM of pelvis and its segmented surface, an accurate 3D pelvimetry system is designed and implemented to measure a comprehensive set of pelvic geometric parameters for the examination of the relationship between these parameters and the difficulty of robotic-assisted laparoscopic radical prostatectomy. This system can be used in both manual and automated manner with a user-friendly interface. A fully automated and robust multi-atlas based segmentation has also been developed to delineate the prostate in diagnostic MR scans, which have large variation in both intensity and shape of prostate. Two image analysis techniques are proposed, including patch-based label fusion with local appearance-specific atlases and multi-atlas propagation via a manifold graph on a database of both labeled and unlabeled images when limited labeled atlases are available. The proposed techniques can achieve more robust and accurate segmentation results than other multi-atlas based methods. The seminal vesicles are also an interesting structure for therapy planning, particularly for external-beam radiation therapy. As existing methods fail for the very onerous task of segmenting the seminal vesicles, a multi-atlas learning framework via random decision forests with graph cuts refinement has further been proposed to solve this difficult problem. Motivated by the performance of this technique, I further extend the multi-atlas learning to segment the prostate fully automatically using multispectral (T1 and T2-weighted) MR images via hybrid \ac{RF} classifiers and a multi-image graph cuts technique. The proposed method compares favorably to the previously proposed multi-atlas based prostate segmentation. The work in this thesis covers different techniques for pelvic image segmentation in MRI. These techniques have been continually developed and refined, and their application to different specific problems shows ever more promising results.Open Acces

Ischiofemoral impingement: the evolutionary cost of pelvic obstetric adaptation.

Funder: Flemmish research foundationThe risk for ischiofemoral impingement has been mainly related to a reduced ischiofemoral distance and morphological variance of the femur. From an evolutionary perspective, however, there are strong arguments that the condition may also be related to sexual dimorphism of the pelvis. We, therefore, investigated the impact of gender-specific differences in anatomy of the ischiofemoral space on the ischiofemoral clearance, during static and dynamic conditions. A random sampling Monte-Carlo experiment was performed to investigate ischiofemoral clearance during stance and gait in a large (n = 40 000) virtual study population, while using gender-specific kinematics. Subsequently, a validated gender-specific geometric morphometric analysis of the hip was performed and correlations between overall hip morphology (statistical shape analysis) and standard discrete measures (conventional metric approach) with the ischiofemoral distance were evaluated. The available ischiofemoral space is indeed highly sexually dimorphic and related primarily to differences in the pelvic anatomy. The mean ischiofemoral distance was 22.2 ± 4.3 mm in the females and 29.1 ± 4.1 mm in the males and this difference was statistically significant (P < 0.001). Additionally, the ischiofemoral distance was observed to be a dynamic measure, and smallest during femoral extension, and this in turn explains the clinical sign of pain in extension during long stride walking. In conclusion, the presence of a reduced ischiofemroal distance and related risk to develop a clinical syndrome of ischiofemoral impingement is strongly dominated by evolutionary effects in sexual dimorphism of the pelvis. This should be considered when female patients present with posterior thigh/buttock pain, particularly if worsened by extension. Controlled laboratory study

Doctor of Philosophy

dissertationFemoroacetabular impingement (FAI) describes subtle structural abnormalities, including femoral asphericity and acetabular overcoverage, which reduce clearance in the hip joint. FAI is a common cause of hip pain for young, athletic adults. The first theme of this dissertation investigated if FAI morphology is more prevalent in athletes and if physical exams could be used to identify individuals with underlying FAI morphology. In a cohort of collegiate football players, 95% were found to have radiographic abnormalities consistent with those seen in FAI patients. This finding not only suggests that athletes, such as football players, may have an increased risk for developing symptomatic FAI, but also highlights that FAI morphology may frequently occur in asymptomatic subjects. In the same cohort, radiographic measures of femoral asphericity and femoral head-neck offset were mildly correlated to maximum internal rotation. As such, athletes with diminished internal rotation in whom hip pain develops should be evaluated for FAI. Altered articulation in FAI hips is believed to cause chondrolabral damage and may lead to osteoarthritis, but FAI kinematics have not been accurately quantified. To this end, the second theme of this dissertation focused on developing, validating, and applying a dual fluoroscopy and model-based tracking protocol to accurately quantify three-dimensional in vivo hip kinematics. In a cadaver experiment, model-based tracking was compared to the reference standard, dynamic radiostereometric analysis. Model-based tracking was found to have a positional error less than 0.48 mm and rotational error was less than 0.58°. The methodology was then applied to evaluate a cohort of asymptomatic control subjects and three patients with differing FAI morphology. The results, which represent the most accurate data collected on hip kinematics to date, demonstrate that hip articulation is a highly complex process, including translation, pelvic motion, no bone contact, and labrum involvement in large ranges of motion. Collected data provide necessary baseline results for future comparison studies and could be used to validate computer simulations of impingement, guide pre-operative planning, and serve as boundary conditions in finite element models investigating chondrolabral mechanics