Mixed reality simulation of rasping procedure in artificial cervical disc replacement (ACDR) surgery

<p>Abstract</p> <p>Background</p> <p>Until quite recently spinal disorder problems in the U.S. have been operated by fusing cervical vertebrae instead of replacement of the cervical disc with an artificial disc. Cervical disc replacement is a recently approved procedure in the U.S. It is one of the most challenging surgical procedures in the medical field due to the deficiencies in available diagnostic tools and insufficient number of surgical practices For physicians and surgical instrument developers, it is critical to understand how to successfully deploy the new artificial disc replacement systems. Without proper understanding and practice of the deployment procedure, it is possible to injure the vertebral body. Mixed reality (MR) and virtual reality (VR) surgical simulators are becoming an indispensable part of physicians’ training, since they offer a risk free training environment. In this study, MR simulation framework and intricacies involved in the development of a MR simulator for the rasping procedure in artificial cervical disc replacement (ACDR) surgery are investigated. The major components that make up the MR surgical simulator with motion tracking system are addressed. </p> <p>Findings</p> <p>A mixed reality surgical simulator that targets rasping procedure in the artificial cervical disc replacement surgery with a VICON motion tracking system was developed. There were several challenges in the development of MR surgical simulator. First, the assembly of different hardware components for surgical simulation development that involves knowledge and application of interdisciplinary fields such as signal processing, computer vision and graphics, along with the design and placements of sensors etc . Second challenge was the creation of a physically correct model of the rasping procedure in order to attain critical forces. This challenge was handled with finite element modeling. The third challenge was minimization of error in mapping movements of an actor in real model to a virtual model in a process called registration. This issue was overcome by a two-way (virtual object to real domain and real domain to virtual object) semi-automatic registration method.</p> <p>Conclusions</p> <p>The applicability of the VICON MR setting for the ACDR surgical simulator is demonstrated. The main stream problems encountered in MR surgical simulator development are addressed. First, an effective environment for MR surgical development is constructed. Second, the strain and the stress intensities and critical forces are simulated under the various rasp instrument loadings with impacts that are applied on intervertebral surfaces of the anterior vertebrae throughout the rasping procedure. Third, two approaches are introduced to solve the registration problem in MR setting. Results show that our system creates an effective environment for surgical simulation development and solves tedious and time-consuming registration problems caused by misalignments. Further, the MR ACDR surgery simulator was tested by 5 different physicians who found that the MR simulator is effective enough to teach the anatomical details of cervical discs and to grasp the basics of the ACDR surgery and rasping procedure</p

Evidence‐based guideline: Neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome

Introduction: The purpose of this study was to develop an evidence‐based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS). Methods: Two questions were asked: (1) What is the accuracy of median nerve cross‐sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2). Results: Neuromuscular ultrasound measurement of median nerve cross‐sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B). Muscle Nerve 46: 287–293, 2012Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92446/1/23389_ftp.pd

Natural History and Outcome of Hepatic Vascular Malformations in a Large Cohort of Patients with Hereditary Hemorrhagic Teleangiectasia

BACKGROUND: Hereditary hemorrhagic telangiectasia is a genetic disease characterized by teleangiectasias involving virtually every organ. There are limited data in the literature regarding the natural history of liver vascular malformations in hemorrhagic telangiectasia and their associated morbidity and mortality. AIM: This prospective cohort study sought to assess the outcome of liver involvement in hereditary hemorrhagic telangiectasia patients. METHODS: We analyzed 16 years of surveillance data from a tertiary hereditary hemorrhagic telangiectasia referral center in Italy. We considered for inclusion in this study 502 consecutive Italian patients at risk of hereditary hemorrhagic telangiectasia who presented at the hereditary hemorrhagic telangiectasia referral center and underwent a multidisciplinary screening protocol for the diagnosis of hereditary hemorrhagic telangiectasia. Of the 502 individuals assessed in the center, 154 had hepatic vascular malformations and were the subject of the study; 198 patients with hereditary hemorrhagic telangiectasia and without hepatic vascular malformations were the controls. Additionally, we report the response to treatment of patients with complicated hepatic vascular malformations. RESULTS: The 154 patients were included and followed for a median period of 44 months (range 12-181); of these, eight (5.2%) died from VM-related complications and 39 (25.3%) experienced complications. The average incidence rates of death and complications were 1.1 and 3.6 per 100 person-years, respectively. The median overall survival and event-free survival after diagnosis were 175 and 90 months, respectively. The rate of complete response to therapy was 63%. CONCLUSIONS: This study shows that substantial morbidity and mortality are associated with liver vascular malformations in hereditary hemorrhagic telangiectasia patients

Applications of Partial Depth Precast Concrete Deck Panels on Horizontally Curved Steel and Concrete Bridges

0-6816Horizontally curved bridges are commonly used for direct connectors at highway intersections as well as other applications. The majority of curved bridges utilize continuous steel curved I-girder or tub girder systems. In recent years, isolated applications of spliced prestressed concrete U-beams have been successfully used for curved bridge applications in Colorado and are currently being considered for use in Texas bridges. One of the most critical construction stages from a stability perspective is placement of the wet concrete deck at which point the girders must support the full construction load of the system until the deck stiffens and acts compositely. Bridges with a curved geometry experience significant torsional forces and require a substantial amount of bracing to control deformation during construction. Bracing in the form of cross frames for steel I-girder systems, top lateral trusses for steel tub girder systems, and lid slabs for concrete U-beams are provided to improve the girder behavior. While partial depth precast concrete panels (PCPs) are commonly used as stay-in-place formwork for straight bridges, the panels are not currently permitted on horizontally curved girder systems in Texas. TxDOT would like to extend the use of PCPs to bridges with curved girders. This report focuses on the stability of PCPs that rest on polystyrene bedding strips. The project studied the behavior for PCPs with and without a positive connection to steel girders and also considered the behavior of the current TxDOT reinforcing details for PCPs with concrete U-beam systems. The experimental portion of this study consists of large-scale PCP shear tests and large-scale combined bending and torsion tests on both a twin steel I-girder system and on a single steel tub girder. The PCP shear tests were used to develop a simple and effective connection between the PCPs and the girder, as well as to empirically determine the in-plane stiffness and strength of the PCP/connection system. The large-scale girder tests were used to investigate the performance of PCPs and their connection to a system that simulates the load experienced in a realistic construction situation. Also, parametric finite element modeling of the PCPs and the curved girder systems were performed and validated with the results from the experimental tests. The finite element models were used to develop an understanding of the fundamental behavior of the steel girder systems in combination with the PCP systems. In addition to focusing on connection methods to the PCPs, guidelines were also developed for cases where the panels can be used on horizontally curved girder systems without a positive connection to the girders

Synthesis of Precast Column Designs for Texas Bridges [Project Summary]

0-6978Using prefabricated bridge elements and systems minimizes on-site operations and closure times during bridge construction and contributes to improving durability and reducing the environmental impact of construction. Prefabrication of bridge columns has been very limited as compared to bridge superstructures and bent caps. Nevertheless, some states have started to develop and implement design concepts for precast concrete columns