Virtual interactive musculoskeletal system (VIMS) in orthopaedic research, education and clinical patient care

The ability to combine physiology and engineering analyses with computer sciences has opened the door to the possibility of creating the "Virtual Human" reality. This paper presents a broad foundation for a full-featured biomechanical simulator for the human musculoskeletal system physiology. This simulation technology unites the expertise in biomechanical analysis and graphic modeling to investigate joint and connective tissue mechanics at the structural level and to visualize the results in both static and animated forms together with the model. Adaptable anatomical models including prosthetic implants and fracture fixation devices and a robust computational infrastructure for static, kinematic, kinetic, and stress analyses under varying boundary and loading conditions are incorporated on a common platform, the VIMS (Virtual Interactive Musculoskeletal System). Within this software system, a manageable database containing long bone dimensions, connective tissue material properties and a library of skeletal joint system functional activities and loading conditions are also available and they can easily be modified, updated and expanded. Application software is also available to allow end-users to perform biomechanical analyses interactively. Examples using these models and the computational algorithms in a virtual laboratory environment are used to demonstrate the utility of these unique database and simulation technology. This integrated system, model library and database will impact on orthopaedic education, basic research, device development and application, and clinical patient care related to musculoskeletal joint system reconstruction, trauma management, and rehabilitation

Biomechanics

Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse dynamics, finite element analysis, and musculoskeletal modeling are used to simulate and investigate human situations in regard to movement and injury. Biomechanical technologies are progressing to answer contemporary medical questions. The future of biomechanics is dependent on interdisciplinary research efforts and the education of tomorrow’s scientists

Pediatric Fractures

This reprint contains original research and review chapters concerning the latest advancements in various topics related to pediatric fractures. Topics include fractures of the face, clavicle, shoulder, elbow, forearm, wrist, pelvis, femur, and tibia; special considerations focus on osteogenesis imperfecta patients; and consideration is also given to general pediatric fracture topics, such as the influence of the COVID-19 pandemic, mortality after pediatric trauma, the effects of NSAID and electronic cigarette use, and chapters on epidemiology and physical activity

Proposta de teste pré-clínico para aferir o desempenho biomecânico de próteses do ombro

Dotoramento em Engenharia MecânicaProsthesis commercialization requires the compliance of regulations that ensure the safe use of prosthesis. However, several prostheses have been withdrawn from the market due to their high failure rates, which is a strong indicator of the lack of suitable pre-clinical tests that allow a more rigorous evaluation of its performance and effectiveness. Thus, the main objective of this doctoral thesis consisted in the development of a pre-clinical test capable of accessing shoulder prosthesis performance. For this purpose, a multi-body model of the intact shoulder containing all muscle groups was used in the first stage in view to identify and characterize those that most contribute to the 90º abduction movement, being them the deltoid, the infraspinatus, the supraspinatus and the subscapularis. Two in vitro models were constructed using composite bone structures of the humerus and of the scapula. In the intact model the cartilage and the inferior glenohumeral ligament were considered and in the implanted model a non-cemented anatomical prosthesis (Comprehensive® Total Shoulder System) and a central post in porous metal for glenoid fixation were used. Strain gage rosettes were used to measure the deformation suffered by the bone structures when positioned at 90º abduction and subjected to loading. Finite element models (FEM) of the intact and implanted shoulder, that replicate the in vitro models, were developed. The FEM were subjected to the same loading scenarios as the in vitro models. The comparison between the strains determined numerically and experimentally allowed FEM validation. Stress and strain distribution inside the bone structures, determined with the FEM of the implanted shoulder, agree with the clinical observations present in literature. This indicates that, in a general way, the developed FEM predicts bone behavior in the presence of a prosthesis and may be considered a pre-clinical test to evaluate shoulder implants performance. To verify that the pre-clinical test developed is sensitive to small differences in implant design and that can be used to predict shoulder prosthesis performance, a new central fixation post in polyethylene was used. Stress and strain distributions determined using the FEM with the new fixation post are (once again) in agreement with clinical observations, confirming that the developed FEM can be used for the pre-clinical evaluation of other shoulder implant designs, allowing to analyze their performance before clinical use.A comercialização de uma prótese requer o cumprimento de regulamentos e normas que garantam a segurança de utilização da mesma. No entanto, diversas próteses têm sido retiradas do mercado devido às elevadas taxas de insucesso que apresentam, sendo este um forte indicador da falta de testes adequados que permitam uma avaliação mais rigorosa do seu desempenho e eficácia. Deste modo, o principal objetivo desta tese de doutoramento consistiu no desenvolvimento de um ensaio pré-clínico capaz de aferir o desempenho biomecânico de próteses do ombro. Para o efeito, numa primeira fase foi utilizado um modelo multi-corpo do ombro intacto contendo todos os grupos musculares com vista a identificar e caracterizar os que mais contribuem para o movimento de abdução de 90°, sendo eles o deltoide, o infraespinhal, o supraespinhal e o subescapular. Foram construídos dois modelos in vitro recorrendo a estruturas ósseas compósitas do úmero e da escápula. No modelo intacto foram consideradas as cartilagens e o ligamento glenohumeral inferior e no modelo implantado foi utilizada uma prótese anatómica não cimentada (Comprehensive® Total Shoulder System) e um pino central de fixação da componente da glenoide revestido com metal poroso. Rosetas de extensometria foram utilizadas para medir as extensões sofridas pelas estruturas ósseas quando posicionadas a 90º de abdução e sob carregamento. Foram desenvolvidos modelos de elementos finitos (EF) do ombro intacto e implantado que replicam os modelos in vitro. Os modelos de EF foram sujeitos aos mesmos cenários de carregamento que os modelos in vitro. A comparação entre as deformações determinadas numericamente e experimentalmente permitiu a validação dos modelos de EF. A distribuição de tensões e deformações no interior das estruturas ósseas, determinadas com o modelo de EF do ombro implantado, estão de acordo com as observações clínicas presentes na literatura. Isto indica que, de uma forma geral, o modelo de EF desenvolvido prevê o comportamento do osso na presença de uma prótese e pode ser considerado um teste pré-clínico para avaliação do desempenho de implantes do ombro. Para verificar que o teste préclínico desenvolvido é sensível a pequenas diferenças no design dos implantes e que pode ser utilizado para prever o desempenho de próteses, foi utilizado um novo pino central de fixação em polietileno. A distribuição de tensões e de deformações determinadas através do modelo de EF usando o novo pino de fixação estão (mais uma vez) de acordo com as observações clínicas, o que confirma que o modelo de EF desenvolvido pode ser utilizado na avaliação préclínica de outros implantes do ombro, permitindo analisar o seu desempenho antes da utilização clínica

Investigating the effect of mechanical loading in a total reversed shoulder implant

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The shoulder joint is a multi-axis synovial ball and socket joint, by having a loose connection it provides a wide degree of freedom; however this means the joint lacks robustness and is prone to damage most commonly from shoulder dislocations. A rotator cuff tear causes major problems in allowing the arm to be lifted beyond a 90˚ abduction position. It is common that this insufficiency aggravates arthritis problems that may have occurred due the rotator cuff tear problem. The study focuses on investigating, describing and quantifying the implant geometric properties to evaluate the joint contact characteristics and use the outcome in redesign the implant. The investigation presents results of finite element analysis on a heavy loading condition on a Verso (reverse) shoulder implant which is validated using experimental data on the same prosthesis. The results are validated within a 5% error margin. A Verso implant is modelled using MIMICS (materialise) and imported into ABAQUS (Simulia, Providence, USA) to analyse the distribution of stress, strain and displacement across the Humerus and Scapula. Details of interaction, boundary conditions, loads and material properties are all obtained from research and applied to the model to portray realistic behaviour. The resulting stress, strain and displacement from this simulation are indicated to show the magnitude and distribution across the entire bone region. This validates the benefits of a Verso implant compared to conventional and long stemmed reverse shoulder implants, as well as provide a basis from which improved designs can be built upon and allow further accurate methods to be developed in analysing shoulder implants effectively

Biomechanical analysis of reverse anatomy shoulder prosthesis

PhD ThesisThis study uses adaptation of an established 3-D biomechanical shoulder model (Newcastle Shoulder Model) to investigate the biomechanical properties of reverse shoulder replacements that have become popular for severe rotator cuff arthropathy. The prosthetic model describes the DELTA® III geometry and can predict muscle and joint contact forces for given motion. A custom contact detection algorithm was developed to investigate the impingement problem. Results showed that the reverse design increases deltoid function by providing sufficient moment arm (42% increase compared to normal anatomy) and restores joint stability by reversing the envelope of joint contact forces. The data showed a good agreement with other biomechanical models. Further in this study scapula and arm kinematics of a group of DELTA III prosthetic subjects were recorded and compared with normal shoulder activity. The scapula kinematics showed increased lateral rotation and even if it is highly variable within the subjects (range:1.2-1.8 times the normal). there is a trend showing that good recovery shoulders have small change in their scapula rhythm and vice versa. The arm kinematics showed that even if the prosthetic subjects were able to complete most activities there was a variable range of humeral movement. Compared to the normal group the average elevation values were high but the internal/external humeral rotation was significantly smaller. The kinematic data were further used and analysed with the model and the results showed large differences in glenoid loading compared to normal shoulders. where there is an increase in superior (range:12%-52% bodyweight) and antero-posterior shear forces (range:8%-39% bodyweight). Impingement results predicted scapula bone notches similar in shape and volume with the literature which was impossible to eliminate without design modifications. The adapted prosthetic model was successfully used to analyse the biomechanics of a reverse design and provide a useful dataset that can be further used for design optimisation

Musculoskeletal shoulder modelling for clinical applications

The shoulder is the most commonly dislocated joint in the human body, with the vast majority of these dislocations being located anteriorly. Anterior shoulder dislocations are commonly associated with capsuloligamentous injuries and osseous defects. Recurrent anterior instability is a common clinical problem and understanding the influence of structural damage on joint stability is an important adjunct to surgical decision-making. Clinical practice is guided by experience, radiology, retrospective analyses and physical cadaver experiments. As the stability of the shoulder is load dependent, with higher joint forces increasing instability, the aim of this thesis was to develop and validate computational shoulder models to simulate the effect of structural damage on joint stability under in-vivo loading conditions to aid surgical decision-making for patients with anterior shoulder instability. The UK National Shoulder Model, consisting of 21 upper limb muscles crossing 5 functional joints, was customised to accurately quantify shoulder loading during functional activities. Ten subject-specific shoulder models were developed from Magnetic Resonance Imaging and validated against electromyographic signals. These models were used to identify the best combination of anthropometric parameters that yield best model outcomes in shoulder loading through linear scaling of personalised shoulder models. These parameters were gender and the ratio of body height to shoulder width (p<0.04) and these model predictions are significantly improved (p<0.02) when compared to the generic model. The forces derived from the modelling were used in two subject-specific finite element models with an anatomically accurate representation of the labrum, to assess shoulder stability through concavity compression under physiological joint loading for pathologies associated with anterior shoulder instability. The key results from these studies were that there is a high risk of shoulder dislocation under physiological joint loading for patients with a 2 mm anterior or 4 mm anteroinferior osseous defect. The loss in anterior shoulder stability in overhead throwing athletes with intact glenoid following biceps tenodesis is compensated by a non-significant increase in rotator cuff muscle force which maintain shoulder stability across all overhead throwing sports, except baseball pitching, where biceps tenodesis has significantly decreased (p<0.02) anterior shoulder stability. The work in this thesis has advanced the technology of musculoskeletal modelling of the shoulder through the inclusion of concavity compression and has applied this to various relevant clinical questions through the further development of an anatomical atlas, and an atlas of tasks of daily living. The applications of such modelling are broader than those addressed here and therefore this work serves as the foundation for potential further studies, including the bespoke design of arthroplasty or other soft tissue procedures.Open Acces