Validation of an extended foot-ankle musculoskeletal model using in vivo 4D CT data

openPer simulare il movimento del corpo umano, è necessario creare dei modelli che rappresentino le strutture anatomiche. In questo elaborato ci si concentrerà su un modello biomeccanico del complesso piede-caviglia implementato in un software per la modellazione muscoloscheletrica, nella fattispecie OpenSim. OpenSim è un software che consente di sviluppare modelli di strutture muscoloscheletriche e creare simulazioni dinamiche in grado di stimare i parametri interni delle strutture anatomiche (come le forze muscolari e di contatto tra le ossa), attraverso la simulazione della cinematica e la cinetica del movimento delle varie strutture coinvolte. Nel presente elaborato, si è partiti dallo studio di un dataset, acquisito da Boey et al. (2020) tramite scansione 4D CT in combinazione con un dispositivo di manipolazione del piede su soggetti sani e pazienti affetti da instabilità cronica di caviglia. In questo modo è stata valutata la cinematica dell’osso del piede durante il cammino simulato. Lo scopo di questo elaborato è quindi validare un modello del complesso piede-caviglia sviluppato da Malaquias et al. (2016), partendo dai dati acquisiti affinché, imponendo il movimento della pedana, la simulazione restituisca delle variabili comparabili a quelle reali. Il modello muscoloscheletrico esteso del complesso piede-caviglia è composto da sei segmenti rigidi e cinque articolazioni anatomiche (caviglia, sottoastragalica, mediotarsica, tarsometatrsale e metatarsofalangea) per un totale di otto gradi di libertà. A questo modello è stata aggiunto una pedana (per simulare il dispositivo di manipolazione utilizzato nella sperimentazione) e sono stati incrementati i gradi di libertà delle articolazioni di caviglia e sottoastragalica, per ottenere tre gradi di libertà ciascuna. Dopodiché, è stato imposto un movimento combinato di inversione\eversione ed ab-adduzione alla pedana ed è stato valutato il movimento del modello del piede rispetto al dataset.To simulate the movement of the human body, it is necessary to create models that represent anatomical structures. In this thesis the focus will be placed on a biomechanical model of the complex foot-ankle implemented in a software for musculoskeletal modeling, in particular OpenSim. OpenSim is software that allows to develop models of musculoskeletal structures and create dynamic simulations capable of estimating the internal parameters of anatomical structures (such as muscle and contact forces between bones), through the simulation of the kinematics and kinetics of the movement of the various anatomical structures involved. In this paper, the starting point was the study of a dataset, acquired by Boey et al. (2020) with 4D CT scan in combination with a foot manipulator device. The study was run on healthy subjects as well as patients with chronic ankle instability. In this way, the kinematics of the movement of the foot bones during simulated gait was evaluated. The aim of this project was to validate a model of the foot-ankle complex, developed by Malaquias et al. (2016), starting from the acquired data, so that, by imposing the movement of the platform, the simulation would return variables comparable to the dataset. This extended musculoskeletal model of the foot-ankle complex is composed of six rigid segments and five anatomical joints (ankle, subtalar, midtarsal, tarsometatarsal, and metatarsophalangeal) for a total of eight degrees of freedom. A footplate was added to this model (to simulate the foot manipulator device utilized in the experiment) and the degrees of freedom of the ankle and subtalar joints were increased, to obtain three degrees of freedom each. After that, a combined inversion\eversion and plantar\dorsiflexion movement was imposed on the footplate and the movement of the foot model was evaluated against the dataset

CHANGES IN LUMBAR JOINT MOMENTS USING A FEMALE SPECIFIC TORSO MODEL DURING RUNNING

The purpose of this study was to quantify the peak lumbar joint flexor / extensor moments following changes in torso and breast mass during running using an innovative computer musculoskeletal model. Kinematic and kinetic data were collected for a female participant running at 2.6 m/s. An MRI scan of the breasts was used to calculate breast mass and centre of mass location relative to the torso. An OpenSim whole body model was customised with two point-mass segments added to the torso to represent the breasts. Key findings have shown that changes in breast mass can cause peak lumbar flexor / extensors moments to be over or underestimated by up to ~18%. These results suggest that including the mass of the breasts in female specific models, during dynamic activities such as running, is an important aspect that must be considered for future work

Biomechanical risk factors and reduced bone health in lower limb amputees

Bone constantly adapts to its surroundings through the formation and resorption of material, controlled by bone modelling and remodelling. Strains produced by mechanical loading are one factor that drive these processes and thus determine bone health. Lower limb amputees (LLA) adopt an asymmetrical movement pattern to compensate for the loss of a limb, resulting in a change in mechanical loading and subsequently a degradation in bone health. The aetiology of the majority of amputations is vascular diseases, which affect bone health. Therefore, it is not clear whether the asymmetrical loading, or comorbidities cause the degradation in bone health in LLA. Finite element models (FEM) are used to generate strain plots and predict the bone's response to mechanical loading. To understand the relationship between the degradation in bone health and asymmetrical loads in LLAs the asymmetrical loads can be applied to a healthy bone using FEMs, or simulated within a healthy population using restrictive devices. Therefore, the overall aim was to investigate the relationship between asymmetrical loading, as observed in LLA’s, and bone health, through the use of semi-subject specific FEMs and restrictive lower limb devices. Study one established a novel image processing method to convert peripheral quantative computed tomography (pQCT) scan images into binary and segment the tibia. The outer perimeter of the tibia was identified and sectioned to produce landmarks. The outer geometry landmarks were used to morph a base FEM, constructed from open source scan images to create semi-subject tibia FEM. Study two applied subject-specific joint reaction and muscle forces to the semi-subject tibia FEM. The strain plots output from Study two were validated against longitudinal geometrical changes from Study three. Study three, used 3D motion capture, pQCT and dual energy x-ray absorptiometry (DXA) to investigate gait and tibial geometry within a lower limb amputee and able-bodied population across twelve months. The coefficient of variation (CV) for able bodied subjects was less than 10% for ground reaction force (GRF) in level walking and less than 4% for bone total area. Study four, used a rigid foot orthosis and a trans-femoral prosthesis, to restrict able-bodied gait. Results showed participants walked significantly slower (p<0.01) in the restricted conditions, with a longer non-restricted step length (p<0.001). The loading rate and maximum GRF were higher in the non-restricted limb (p<0.05). Larger knee adductor moments were shown in the un-restricted leg in the trans-tibial condition (p<0.05). This thesis presents a novel method of constructing semi-subject specific FEMs from pQCT scans. This can be used to further investigate the link between asymmetrical loading and bone health in LLA's and other populations with asymmetrical gait. The use of restrictive devices allow investigation into LLA's specifically, without the interference of prosthetic variability, or comorbidities

Construction and assessment of a computer graphics-based model for wheelchair propulsion

Upper limb overuse injuries are common in manual wheelchair using persons with spinal cord injury (SCI), especially those with tetraplegia. Biomechanical analyses involving kinetics, kinematics, and muscle mechanics provide an opportunity to identify modifiable risk factors associated with wheelchair propulsion and upper limb overuse injuries that may be used toward developing prevention and treatment interventions. However, these analyses are limited because they cannot estimate muscle forces in vivo. Patient-specific computer graphics-based models have enhanced biomechanical analyses by determining in vivo estimates of shoulder muscle and joint contact forces. Current models do not include deep shoulder muscles. Also, patient-specific models have not been generated for persons with tetraplegia, so the shoulder muscle contribution to propulsion in this population remains unknown. The goals of this project were to: (i) construct a dynamic, patient-specific model of the upper limb and trunk and (ii) use the model to determine the individual contributions of the shoulder complex muscles to wheelchair propulsion. OpenSim software was used to construct the model. The model has deep shoulder muscles not included in previous models: upper and middle trapezius, rhomboids major and serratus anterior. As a proof of concept, kinematic and kinetic data collected from a study participant with tetraplegia were incorporated with the model to generate dynamic simulations of wheelchair propulsion. These simulations included: inverse kinematics, inverse dynamics, and static optimization. Muscle contribution to propulsion was achieved by static optimization simulations. Muscles were further distinguished by their contribution to both the push and recovery phases of wheelchair propulsion. Results of the static optimization simulations determined that the serratus anterior was the greatest contributor to the push phase and the middle deltoid was the greatest contributor to the recovery phase. Cross correlation analyses revealed that 80% of the investigated muscles had moderate to strong relationships with the experimental electromyogram (EMG). Results from mean absolute error calculations revealed that, overall, the muscle activations determined by the model were within reasonable ranges of the experimental EMG. This was the first wheelchair propulsion study to compare estimated muscle forces with experimental fine-wire EMG collected from the participant investigated

Cancellous bone and theropod dinosaur locomotion. Part II—a new approach to inferring posture and locomotor biomechanics in extinct tetrapod vertebrates

This paper is the second of a three-part series that investigates the architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is widely known to be highly sensitive to its mechanical environment, and therefore has the potential to provide insight into locomotor biomechanics in extinct tetrapod vertebrates such as dinosaurs. Here in Part II, a new biomechanical modelling approach is outlined, one which mechanistically links cancellous bone architectural patterns with three-dimensional musculoskeletal and finite element modelling of the hindlimb. In particular, the architecture of cancellous bone is used to derive a single ‘characteristic posture’ for a given species—one in which bone continuum-level principal stresses best align with cancellous bone fabric—and thereby clarify hindlimb locomotor biomechanics. The quasi-static approach was validated for an extant theropod, the chicken, and is shown to provide a good estimate of limb posture at around mid-stance. It also provides reasonable predictions of bone loading mechanics, especially for the proximal hindlimb, and also provides a broadly accurate assessment of muscle recruitment insofar as limb stabilization is concerned. In addition to being useful for better understanding locomotor biomechanics in extant species, the approach hence provides a new avenue by which to analyse, test and refine palaeobiomechanical hypotheses, not just for extinct theropods, but potentially many other extinct tetrapod groups as well

Influence of obesity on biomechanics models and simulations

Digital Anthropometry, also known as 3D body scanning, has been making its way into biomechanical research in recent years. Biomechanical simulations of motions are commonly developed using a generic model of the human body scaled according to the weight and height of the subject. This assumes that the contribution of each body segment to the total mass remains identical. The goal of this project is to scan human subjects with various morphologies to quantify the Body Mass Index above which a subject-specific musculoskeletal model is necessary for the accurate evaluation of body dynamics.Lew Wentz FoundationMechanical and Aerospace Engineerin

VALIDATION OF A DXA-BASED METHOD FOR OBTAINING INERTIA TENSORS: 'WHEN PIGS FLY'

This paper examines the accuracy of body segment inertia tensors estimated by combining information from dual-energy X-ray absorptiometry and a three-dimensional modelling technique proposed by Zatsiorsky et al. (1 990) (DXAIVol method). The inertia tensor of a frozen pig cadaver was estimated using the novel DXAlVol method and traditional compound pendulum techniques. The pig cadaver was projected through the air and the experimental 'ground truth kinematics' were recorded. Simulated kinematics of the pig cadaver flight were generated using the inertia tensor derived from the DXAlVol and compound pendulum methods and compared to the ground truth kinematics. Simulations based on the novel D W o l method's inertia tensor traded the experimentally recorded flight of the frozen pig cadaver with superior accuracy

Master of Science

thesisStabilization of the head is critical for running. Homo sapiens possess several anatomical features that are useful for head stabilization. In order to test the functional value of some of these features, namely the location of the center of mass and the muscular connection between the skull and shoulder girdle, mechanical models are created. These mechanical models are representative of Homo sapiens and their ancestors. These models are subject to the kinematics and dynamics of a complete running gait cycle. The results show that the location of the center of mass for the Homo sapiens is superior to that of its ancestors for the purposes of head stabilization. Furthermore, the results show that the muscular connection between the skull and the shoulder girdle of Homo sapiens permit the counter rotation of the shoulders to reduce the energy needed to stabilize the head during running

Advancing clinical gait analysis through technology and policy

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 161-165).Quantitatively analyzing human gait biomechanics will improve our ability to diagnose and treat disability and to measure the effectiveness of assistive devices. Gait analysis is one technology used to analyze walking, but technical as well as economic, social, and policy issues hinder its clinical adoption. This thesis is divided into two parts that address some of these issues. Part I focuses on the role public policies have in advancing gait analysis. Through an analysis of gait analysis technologies, case studies of MRI and CT Angiography, and a high-level analysis of data standards used in gait analysis, it concludes that policies cannot directly create the institutional structures and the data standards required to advance gait analysis as a clinical diagnostic tool. Only through indirect means, such as research funding, can policies support the development of organizations to take ownership of gait analysis technologies. Part I also concludes that policies should not fund development of gait technologies but instead should fund research units working on data standards and accurate human body models. Part II focuses on a technical issue in gait analysis, namely, how to address uncertainties in joint moment calculations that occur from using different body segment inertial parameter estimation models. This is identified as a technical issue needing attention from our broader policy analysis in Part I. Using sensitivity studies of forward dynamics computer simulations coupled with an analysis of the dynamical equations of motion, Part II shows that joint moment variations resulting from different segment inertial parameters are significant at some parts of the gait cycle, particularly heel strike and leg swing.(cont.) It provides recommendations about which segment inertial parameters one should estimate more accurately depending on which joints and phases of the gait cycle one is interested in analyzing.by Junjay Tan.S.M.S.M.in Technology and Polic

Development of a neuromusculoskeletal computer model in a chondrodystrophic dog.

Intervertebral disc disease (IVDD) is a naturally occurring disease in dogs that produces a spontaneous injury to the spinal cord. IVDD is characterized by mineralization of the intervertebral disc nucleus pulposus, which reduces its load bearing capacity and results in high rates of intervertebral disc herniation (IVDH). IVDH is disproportionately present in Dachshunds compared to other breeds, affecting an estimated 1 in 5 Dachshunds during their lifetime (Levine, J. M. et al., 2011). Assessment of injury severity and recovery in animal models is generally performed using a point scale, where subjects are graded according to metrics such as pain perception, joint movement, and limb coordination (Basso et al., 1995; Levine, G. J. et al., 2009; Olby, N. J. et al., 2001). Although these methods provide a general view of recovery, they are unable to quantify metrics such as joint motion/torque and muscle activation/force produced during specific phases of gait. OpenSim is an open source software package that allows users to estimate joint kinematics/torques and muscle forces/activations in a musculoskeletal model, which can be scaled to a subject’s dimensions (Delp et al., 2007). Generic musculoskeletal models have been developed in the OpenSim platform for humans (Delp et al., 1990), cats (Keshner et al., 1997), and rats (Johnson et al., 2008), however to the author’s knowledge no model has been developed for dogs. April 12, 2016 The purpose of the proposed study was to develop a subject-specific neuromusculoskeletal computer model of a healthy dog using OpenSim software (Delp, Anderson et al. 2007) to deduce patterns of muscle activity during locomotion. The long- term goal of this study is to utilize the model to inform rehabilitation strategies to enhance recovery and function in dogs with SCI based upon an improved understanding of muscle activation patterns. Additionally, the ability to characterize muscle activation patterns will provide a tool for quantifying the efficacy of therapeutic interventions in a canine model that could allow for potential therapeutic advancement in both dogs and humans. The specific aims of this study were: 1. To characterize joint kinematics of healthy Dachshunds during walking gait. 2. To compare model-predicted joint kinematics to measured joint kinematics in healthy Dachshunds during walking gait. H1: Pelvic limb joint range of motion of the model-predicted kinematics will not be different from kinematics calculated from marker trajectory data. H2: Measured motion tracking marker trajectories will not be different from virtual model-predicted marker trajectories. 3. To quantify model sensitivity to changes in maximum muscle isometric force. H3: Varying maximum muscle isometric force will affect peak muscle activation. v April 12, 2016 To address these aims, a bilateral 3D model of the bony structures of the pelvis and pelvic limb (femur, tibia/fibula, phalanges, and metatarsals) and muscles was created using computed tomography (CT) imaging data. Parameters for the OpenSim model such as muscle origins and insertions, muscle cross-sectional area, and tendon slack length were obtained using computed tomography data or values from literature studies. Kinematic and kinetic data were incorporated in OpenSim to estimate joint kinematics and muscle activation patterns during locomotion. In this study a subject-specific canine pelvic limb neuromusculoskeletal OpenSim model was developed based upon anatomically accurate data, as well as parameters of dogs described in literature. This model included representation of bilateral pelvic limb boney segments and muscles. This model was used to predict kinematics, muscle activation patterns and muscle forces during simulated gait. Findings illustrated that the model provided a reasonable approximation of joint kinematics as compared to measured joint kinematics, based on correlation coefficients calculated between modeled and measured joint kinematics and motion tracking marker trajectory data. The extensor digitorum longus, tibialis cranialis, adductor, vastus lateralis/medialis, rectus femoris, and tensor fascia lata were primarily active during stance. The vastus lateralis/medialis, rectus femoris, tensor fascia lata, sartorius and gluteus medius were active during the first half of swing, while the adductor, semimembranosus, semitendinosus, and biceps femoris were active during the second half of swing. These activation patterns compare similarly with those found in the scientific literature, despite vi April 12, 2016 vii inherent differences in the comparison. This study illustrates the utility of an OpenSim model by demonstrating the ability to accurately model kinematic data, and predict muscle activation patterns during gait. Future work should involve further verification of modeled joint torques and muscle parameters, as well as describe small muscles not included in the current model