Customization and topology optimization of compression casts/braces on two-manifold surfaces

This paper applies the topology optimization (TO) technique to the design of custom compression casts/braces on two-manifold mesh surfaces. Conventional braces or casts, usually made of plaster or fiberglass, have the drawbacks of being heavy and unventilated to wear. To reduce the weight and improve the performance of a custom brace, TO methods are adopted to optimize the geometry of the brace in the three-dimensional (3D) space, but they are computationally expensive. Based on our observation that the brace has a much smaller thickness compared to other dimensions and the applied loads are normal forces, this paper presents a novel TO method based on thin plate elements on the two-dimensional manifold (2-manifold) surfaces instead of 3D solid elements. Our working pipeline starts from a 3D scan of a human body represented by a 2-manifold mesh surface, which is the base design domain for the custom brace. Similar to the concept of isoparametric representation, the 3D design domain is mapped onto a two-dimensional (2D) parametric domain. An Finite Element Analysis (FEA) with bending moments is performed on the parameterized 2D design domain, and the Solid Isotropic Material with Penalization (SIMP) method is applied to optimize the pattern in the parametric domain. After the optimized cast/brace is obtained on the 2-manifold mesh surface, a solid model is generated by our design interface and then sent to a 3D printer for fabrication. Compared with the optimization method with solid elements, our method is more efficient and controllable due to the high efficiency of solving FEA in the 2D domain

A Passive Brace for the Treatment of Scoliosis Utilizing Compliant Mechanisms

Adolescent idiopathic scoliosis is a deformity of the spine that affects 2-3% of the population and often requires treatment in the form of a brace. Most successful braces consist of a rigid plastic shell that can be uncomfortable and limit the patient\u27s ability to perform activities of daily living. The greatest cause of treatment failure is patient unwillingness to wear the brace for the prescribed amount of time, up to 23 hours each day. Other flexible braces have been designed to overcome this obstacle, but they have a lower success rate and other drawbacks. It was proposed in this thesis that compliant mechanisms can provide the lateral stiffness required for correction combined with compliance in other directions since they naturally offer relativestiffness and compliance directions. Throughout the process of designing the brace, multiple valuable contributions were generated for various fields of study. The development of the kinematic profile of the spine included determining the locations of the three primary spinal motions and specific axes of rotation for each motion. A corrective force paradigm was used for design rather than the standard displacement paradigm, therefore, requiring a complete understanding of the force profile applied by the brace, which is not found in literature. The force system was determined through an integration of the pressure applied to the torso by a brace. In order to design in 3-dimensions, the Building Block Approach for compliant mechanism synthesis was expanded. This method was used to design the overall mechanism topology. Finally, an iteration of the brace was designed, produced, and tested. Overall, the tools necessary to design a compliant scoliosis brace were developed and can now be easily used to iterate through designs

Étude biomécanique du traitement de la scoliose idiopathique par orthèse: effets des paramètres de conception des corsets sur les corrections géométriques et sur les contraintes internes du rachis.

RÉSUMÉ La scoliose est une déformation tridimensionnelle évolutive de la colonne vertébrale et de la cage thoracique. Pour des déformations modérées, le principal traitement utilisé est le traitement par corset. Son objectif est, à court-terme, de réduire les déformations scoliotiques et, à long-terme, d’en empêcher la progression. Toutefois le traitement par corset tel qu’il est effectué actuellement n’est pas optimal. La conception des corsets repose encore principalement sur des principes empiriques et l’expérience variée des orthésistes. Aucune étude, clinique ou numérique, n’a étudié directement l’effet des paramètres de conception d’un corset sur son efficacité. De nombreuses controverses existent encore de ce fait sur les paramètres de conception optimaux. De même, aucune étude, expérimentale ou numérique, n’a tenté de prouver que le traitement par corset permet de modifier favorablement les contraintes agissant sur les plaques de croissance d’un sujet scoliotique, démontrant ainsi de façon théorique l’efficacité du traitement à empêcher la progression des déformations. L’objectif général de ce projet est donc d’étudier l’effet du design des corsets sur la correction immédiate des déformations scoliotiques et sur les contraintes agissant sur les plaques de croissance. L’hypothèse que nous souhaitons vérifier est que le traitement par corset peut annuler l’asymétrie des contraintes de compression s’exerçant sur les plaques de croissance à l’apex des courbures scoliotiques mais que cet effet est dépendant des paramètres de conception du corset, ce qui nécessite un ajustement optimal. Cette étude a été divisée en 5 parties. Une méthode a tout d’abord été développée pour représenter les forces de gravité sur un modèle éléments finis (MEF) du tronc d’un patient scoliotique tout en respectant sa géométrie 3D. Un processus d’optimisation a permis de déterminer les forces à soustraire au MEF, dont la géométrie a été construit à partir d’une reconstruction 3D par radiographies biplanaires du patient, afin d’obtenir suite à l’application de la gravité un modèle correspondant à la géométrie réelle du patient. La différence entre la position 3D des vertèbres issue des radiographies et la position simulée des vertèbres du modèle EF après application de la gravité s’est avéré être inférieure à 3 mm. Les contraintes de compression et les moments d’inflexion latérale agissant sur les plateaux vertébraux ont été calculés. Il a été constaté que dans le plan frontal la concavité des courbures scoliotiques était soumise à des contraintes de compression moyennes supérieures de 0.1 à 0.4 MPa à celles de la convexité.----------ABSTRACT Scoliosis is defined as a three-dimensional deformity of the spine and rib cage. For moderate deformities, bracing is the most common treatment. Its aim is to reduce the scoliotic deformities in a short-term perspective and to prevent their progression in a long-term perspective. The brace treatment is however not optimal as it is practiced today. The braces design is mostly based on empirical principles and on the experience of the orthotists. The effects of the design parameters of a brace on its efficiency have never been studied, experimentally or numerically. As a consequence, the optimal brace design parameters are still controversial. No study demonstrated that the brace treatment modifies favorably the stresses in the vertebral growth plates of a scoliotic patient, proving thus that the brace treatment is theoretically efficient in preventing the scoliotic deformities from progressing. The objective of this project was consequently to study the effect of the brace design on the immediate correction of the scoliotic deformities and on the spinal stresses. The hypothesis we want to verify is that the brace treatment is able to nullify the asymmetry of the compressive stresses exerted on the growth plates at the apex of the scoliotic curves but this effect depends on the design parameters of the brace and an optimal adjustment is thus required. This study was divided into 5 parts. A simulation process was firstly developed to represent the gravity forces in a finite element model (FEM) of the trunk of a scoliotic patient. An optimization process computed the forces to substract to the FEM, based on the 3D reconstruction of biplanar x-rays of the patient, in order to obtain after the inclusion of the gravity forces a model corresponding to the actual geometry of the patient. The difference in the vertebral positions between the geometry acquired form radiographs and the computed geometry of the model including the gravity forces was inferior to 3 mm. The forces and compressive stresses in the scoliotic spine were then computed. An asymmetrical load in the coronal plane, particularly at the apices of the scoliotic curves, was present. Difference of mean compressive stresses between concavity and convexity of the scoliotic curves ranged between 0.1 and 0.4 MPa

Évaluation biomécanique du corset de providence pour le traitement conservateur de la scoliose

RÉSUMÉ La scoliose idiopathique adolescente (SIA) est une déformation tridimensionnelle de la colonne vertébrale et de la cage thoracique. Elle touche 2-3 % de la population adolescente, dont 10% nécessiteront un traitement. Les patients avec une courbe entre 20-45° reçoivent un traitement conservateur par corset. Les forces correctrices agissant sur le rachis dépendent du design et de l’ajustement du corset, ainsi que de la posture et des sollicitations musculaires du patient. Les orthèses thoraco-lombo-sacrés (TLSOs) sont utilisés pour les courbes modérées avec un apex inférieur à la 8ème vertèbre thoracique (T8). Comme le corset est habituellement porté 23 heures par jour, son mécanisme d’action n’apparaît pas optimal. Des corsets "de nuit" existent, et ils visent à améliorer l’adhérence du patient et à introduire une correction active de nuit, et une plus grande latitude le jour, permettant au patient de participer aux activités sportives. Les corsets de nuit ont moins d’effets négatifs sur le fonctionnement psycho-social, le sommeil, le mal au dos, et l’image du corps. Le corset de nuit de Providence a été introduit en 1992. Des forces latérales et rotationnelles directes sont appliquées au sommet des courbes à travers un système de 3 points d’appui. Après la prise de mesures, le corset est fabriqué en utilisant une technique de conception/fabrication assistée par ordinateur (CFAO). Souvent, une surcorrection est observée sur les radiographies en position couchée dans le corset. Les premiers résultats de l’application du corset de Providence ont été présentés en 2001. Les concepteurs du corset rapportent une correction moyenne de 90% pour les courbes doubles, et encore une meilleure correction pour les courbes simples. Le taux de réussite global est de 50% à 75%. La position couchée est également connue pour réduire les courbes scoliotiques, en particulier lors de chirurgies d'instrumentation. De nouvelles approches de simulation de corset basées sur des modèles numériques par éléments finis permettent dorénavant de tester de façon virtuelle et d’optimiser l’effet des corsets pour des patients donnés avant leur fabrication. Les corsets TLSOs sont maintenant simulés avec une représentation réaliste de l'interface de contact entre le tronc et le corset du patient. Malgré le fait que le corset de Providence est disponible depuis plus de 20 ans, la biomécanique de ce traitement ainsi que l'effet des paramètres de conception de corset et de la position couchée ne sont toujours pas bien décrites. Le modèle CFAO est choisi parmi une banque de données de corset sur la base de l'inventaire de moule, puis soumis à une dérotation de la section thoracique. Cependant, l'impact de la conception et des ajustements du corset sur les résultats ne sont pas bien compris, car aucune méthode d'évaluation n’est utilisée avant la fabrication.L'objectif de ce projet était donc de modéliser la biomécanique et d'évaluer le corset de nuit de Providence pour le traitement de la scoliose idiopathique de l'adolescent afin de mieux comprendre son mode d'action.----------ABSTRACT Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformation of the spine and rib cage. It affects 2-3% of the adolescent population, of which 10% will require treatment. Patients with a curve between 20-45° usually receive a conservative treatment by brace. Corrective forces acting on the spine depend on the design and adjustment of the brace, as well as the posture and muscular activity of the patient. Thoracolumbosacral orthoses (TLSOs) are commonly used for moderate curves with an apex inferior to the 8th thoracic vertebra (T8). As the brace is usually worn 23 hours a day, its mechanism of action seems not optimal. “Nighttime” braces exist, and they are designed to improve patient adherence and to introduce an active correction by allowing the patient to participate in sports activities. Nighttime braces have less negative impact on the psycho-social functioning, sleep, back pain and body image. Providence nighttime brace was introduced in 1992. Direct lateral and rotational forces are applied on the summits of curves through a 3-point pressure system with bolsters. After taking measurements, the brace is manufactured using computer-aided design and manufacturing (CAD/CAM) technique. An overcorrection is often observed on supine in-brace radiographs. The first results of the application of Providence brace were presented in 2001. Its designers claim an average in-brace correction of 90% for double curves, and a better correction for simple curves. Overall success rate is 50% to 75%. The prone position is also known to reduce the scoliotic curves, especially during instrumentation surgeries. New brace simulation approaches based on numerical finite element models (FEM) are now used to test virtually and optimize the effect of braces on given patients before their manufacturing. TLSOs are now simulated with a realistic representation of the contact interface between the trunk and the patient's brace. Despite the fact that the Providence brace has been available for more than 20 years, the biomechanics of this treatment and the effect of the brace design parameters and supine position are still not well described. The CAD/CAM model is selected from a brace database based on mold inventory, then subjected to derotation of the thoracic section. However, the impact of brace design and adjustments on outcomes are not well understood, as no assessment method is used prior to brace fabrication. Hence the objective of this project was to model and evaluate the biomechanics of nighttime Providence brace for the treatment of idiopathic adolescent scoliosis to better understand its mode of action. The hypotheses we addressed were that the biomechanical simulation tool allows to realistically simulate the application of the nighttime brace for the treatment of scoliosis, and that the supine position has an important role in the correction mechanism

Fabrication of drug eluting medical device for treating stenosis by 3D printing and dip coating using aspirin as a model drug

3D printing is a new innovative manufacturing method for fabrication of customized medical devices. The customized medical devices & long-lasting implantable devices.has increasing demand for addressing some critical cases in surgeries. The main aim of this work was to explore the potential of 3D printing in Fabrication of medical devices and prosthetics. The characters of the polymers, the features of softwares were studied. The study showed that drug loading into filament through hot melt extrusion and followed by 3D printing has many defects such as denaturing of drugs at higher printing temperatures. The invention discloses the dip coating process  after fabrication of a 3D printed polymer structure. The drug release depends up on the surface area of the device, coated polymer, concentration of drug and thickness of the coat. The method for preparing the personalized drug eluting coronary stent / Bone wedges / Braces comprises the step that according to image data of coronary angiogram or volume rendered data from CT scans. The designing was done by adopting a QCA technique for measuring the diameter of a diseased coronary artery and reconstructing in a three-dimensional manner. According to indexes such as lesion vascular diameter, lesion length and lesion vascular pattern, a personalized coronary stent can be made for each patient in a customized manner and a stent most suitable for the lesion state of a patient can be prepared. Keywords: 3D printing, manufacturing method, Fabrication of medical device

Advances on Scoliogeny, Diagnosis and Management of Scoliosis and Spinal Disorders

This book contains research articles on the advances in the aetiology of idiopathic scoliosis (IS), the spinal growth related to the implementation of growth modulation for the surgical treatment of early-onset IS, the non-surgical treatment of IS using Physiotheraputic Scoliosis Specific Exercises, and braces. Additionally, it focuses on issues related to surgical treatment, issues related to body posture and the quality of life of this sensitive group of people. The high quality of published papers in this Special Issue of the JCM serve these objectives

The Effect of Spinal Cord Stimulation and Video Games Training on Body-machine Interface Control

Damage to the spinal cord causes long-lasting loss of motor and sensory function, and currently, there is no ‘cure’ for paralysis. However, even people with severe spinal cord injuries (SCI) have some residual mobility. Studies have shown that transcutaneous electrical spinal cord stimulation (tSCS) combined with functional training targeting residual mobility can further improve the motor function of individuals with SCI. In this study, we present a technical framework that aims to enhance rehabilitation outcomes by targeting residual mobility through a motor training-based approach. Our technical framework centers around a non-invasive body-machine interface (BoMI) that relies on the use of several inertial measurement units (IMUs) to capture the residual mobility of the participant’s body and translate it into the ability to control a two-dimensional (2D) cursor on a computer screen. Participants can manipulate this 2D computer cursor by using their residual body movements to complete a series of self-developed tasks for functional motor training, such as center-out reaching tasks and 2D video games. Additionally, tSCS electrodes were placed at designated spinal segments during the motor training and attempted to produce neuromodulatory effects that facilitate leg and trunk movement and performance of BoMI control. Subsequently, our work aimed to investigate the effect of using non-invasive tSCS and immersive 2D video games on participants’ performance of motor control and learning rate through the above training framework. Participants\u27 performance was recorded and quantified using four assessment metrics based on different center-out reaching tasks. Therefore, a multi-day experiment recruiting both unimpaired control participants and people with SCI was conducted to investigate the effect of training with tSCS and 2D video games on the performance of center-out reaching tasks. Our findings revealed that the BoMI performance of the unimpaired control group improved after training with center-out reaching tasks, and the final performance and learning rate were unrelated to the application of tSCS. However, the effect of tSCS on individuals with SCI varied from person to person. Specifically, we found that tSCS had a clear facilitation effect on the BoMI performance, resulting in a better final performance and a significant learning rate for SCI participant BMS002 but not for SCI participant BMS001. Moreover, our results showed that training with reaching tasks and video games resulted in similar final BoMI performance within the unimpaired control group, but training with reaching tasks generated a better learning rate. Regarding participants with SCI, training with video games led to a significant learning rate in BMS001 and a non-significant learning rate in BMS002. In addition, we observed that there was no significant difference between the final performance after training with reaching task and video games in both unimpaired control and SCI participants. In conclusion, our results suggest that functional training with tSCS could be an effective approach to enhancing motor function and learning rate for individuals with SCI. Also, video games could be considered as a promising training strategy, equivalent to traditional center-out reaching tasks

Development And Human Performance Evaluation Of Control Modes Of An Exo-Skeletal Assistive Robotic Arm (esara)

This research was conducted to assist with functional tasks for a targeted group of individuals with spinal cord injury (SCI); with C5 to C7 level of injury relating to upper extremity movement. The specific population was selected as the existing technology was either too expensive, too bulky or was unable to address their needs in regards to upper extremity mobility. In addition, no platforms allowed multimodal control options for customization or provided a methodology for this crucial evaluation. The motivation of this research was to provide a methodology for selecting the appropriate control of an assistive device based on the range of basic human movements that were possible by the population under consideration (button pushing, lever sliding, and speech). The main idea was to create an evaluation methodology based on a user platform with multiple modes of control. The controls were developed such that they would allow operation of the device with respect to the capabilities of SCI participants. Engineering advancements have taken assistive robotics to new dimensions. Technologies such as wheelchair robotics and myo-electronically controlled systems have opened up a wide range of new applications to assist people with physical disabilities. Similarly exo-skeletal limbs and body suits have provided new foundations from which technologies can aid function. Unfortunately, these devices have issues of usability, weight, and discomfort with donning. The Smart Assistive Reacher Arm (SARA) system, developed in this research, is a voice-activated, lightweight, mobile device that can be used when needed. SARA was built to help overcome daily reach challenges faced by individuals with limited arm and hand movement capability, such as people with cervical level 5-6 (C5-6) SCI. The functional reacher arm with voice control can be beneficial for this population. Comparison study with healthy participants and an SCI participant shows that, when using SARA, a person with SCI can perform simple reach and grasp tasks independently, without someone else\u27s help. This suggests that the interface is intuitive and can be easily used to a high-level of proficiency by a SCI individual. Using SARA, an Exo-Skeletal Assistive Robotic Arm (eSARA) was designed and built. eSARA platform had multiple modes of control namely, voice (ballistic mode with no extremity movement), button (ballistic mode with minor extremity movement) and slider (continuous mode with major extremity movement). eSARA was able to extend a total of 7 inches from its original position. The platform also provided lift assist for users that can potentially enable them to lift up to 20lbs.The purpose of eSARA was to build a platform that could help design a methodology to select the modality for a specific level of SCI injury or capability. The eSARA platform\u27s Human Machine Interface (HMI) was based on two experiments `Fine movement experiment\u27 and `Gross movement experiment\u27. These experiments tested the reaching, grasping and lifting ability of the platform. Two groups of healthy young adults were selected to perform the experiment. The first group, 12 healthy participants, had no movement restrictions. The second group, 6 Occupational Therapy students, that could mimic restrictions similar to those of a level 5-6 SCI individual. The experiment was also conducted by an SCI individual. The results of the 2 groups from both the experiments were compared with the results of the SCI participant. It was found that the SCI participant\u27s time performance to finish the tasks was comparable to the average of the healthy participants. It was concluded that the developed methodology and platforms could be used to evaluate the control modes needed in order to customize the system to the capabilities of SCI individual. . These platforms can be tested for a broader range of participants including participants with arthritis, recovering from paralysis and seniors with movement issues