Gait analysis methods in rehabilitation

Introduction: Brand's four reasons for clinical tests and his analysis of the characteristics of valid biomechanical tests for use in orthopaedics are taken as a basis for determining what methodologies are required for gait analysis in a clinical rehabilitation context. Measurement methods in clinical gait analysis: The state of the art of optical systems capable of measuring the positions of retro-reflective markers placed on the skin is sufficiently advanced that they are probably no longer a significant source of error in clinical gait analysis. Determining the anthropometry of the subject and compensating for soft tissue movement in relation to the under-lying bones are now the principal problems. Techniques for using functional tests to determine joint centres and axes of rotation are starting to be used successfully. Probably the last great challenge for optical systems is in using computational techniques to compensate for soft tissue measurements. In the long term future it is possible that direct imaging of bones and joints in three dimensions (using MRI or fluoroscopy) may replace marker based systems. Methods for interpreting gait analysis data: There is still not an accepted general theory of why we walk the way we do. In the absence of this, many explanations of walking address the mechanisms by which specific movements are achieved by particular muscles. A whole new methodology is developing to determine the functions of individual muscles. This needs further development and validation. A particular requirement is for subject specific models incorporating 3-dimensional imaging data of the musculo-skeletal anatomy with kinematic and kinetic data. Methods for understanding the effects of intervention: Clinical gait analysis is extremely limited if it does not allow clinicians to choose between alternative possible interventions or to predict outcomes. This can be achieved either by rigorously planned clinical trials or using theoretical models. The evidence base is generally poor partly because of the limited number of prospective clinical trials that have been completed and more such studies are essential. Very recent work has started to show the potential of using models of the mechanisms by which people with pathology walk in order to simulate different potential interventions. The development of these models offers considerable promise for new clinical applications of gait analysis

Development of a global gait symmetry score using biomechanical parameters

The clinical implications of an asymmetric gait pattern led to a growing interest in restoring gait symmetry in clinical populations. This entails the accurate and reliable assessment of overall gait symmetry. Given the limitations of pre-existing symmetry indices, the aim of this thesis was to develop and test a new global index for gait symmetry that comprised information from the lower limbs, trunk and pelvis, throughout the entire gait cycle. To achieve this goal, four studies were conducted. In the first study, a global symmetry index, based on the bilateral differences in 3D joint angles, was developed and tested by comparing the scores obtained by healthy individuals in three walking conditions, in which different levels of asymmetry were induced artificially. The second and third studies analysed the inter-session agreement and reliability of this and other global indices, also in a healthy group. Based on the obtained results, the first index was refined by replacing the joint angles with the joint linear positions. The final study tested the ability of this new index to detect the presence of higher levels of asymmetry in a group of patients with an expected asymmetric gait pattern. These studies showed that while symmetry indices based on joint angles can detect acute changes in symmetry within the same session, their poor inter-session repeatability prevents their application to assess differences in symmetry over time and among individuals. On the other hand, the final index proposed in this thesis has good inter-session agreement and reliability, and is sensitive to the increased level of asymmetry typically found in patients with an asymmetric gait pattern. These findings suggest that this index may be a useful tool to assess gait symmetry in a clinical context.As implicações clínicas de um padrão de marcha assimétrico levaram ao crescente interesse na recuperação da simetria da marcha em populações clínicas. Isto requer uma avaliação precisa e fiável da simetria da marcha na sua globalidade. Dadas as limitações dos índices de simetria pré-existentes, o objectivo desta Tese foi desenvolver e testar um novo índice global de simetria da marcha que abrangesse informação dos membros inferiores, do tronco e da pélvis, ao longo do ciclo completo da marcha. Para alcançar este objectivo, foram realizados quatro estudos. No primeiro, este índice, desenvolvido com base nas diferenças bilaterais de ângulos articulares em 3D, foi testado através da comparação dos resultados obtidos por indivíduos saudáveis em três condições de marcha, nas quais diferentes níveis de assimetria foram induzidos artificialmente. Os segundo e terceiro estudos analisaram a concordância e fiabilidade inter-sessão deste e de outros índices globais, também num grupo saudável. Com base nos resultados obtidos, o primeiro índice foi aperfeiçoado, substituindo os ângulos inter-segmentares pelas posições lineares das articulações. O estudo final testou a capacidade deste novo índice detectar a presença de níveis de assimetria superiores num grupo de indivíduos, cujo padrão de marcha é expectavelmente assimétrico. Estes estudos mostraram que, enquanto os índices baseados em ângulos articulares conseguem detectar alterações agudas na simetria dentro da mesma sessão, a sua baixa repetibilidade entre sessões desaconselha a sua aplicação para avaliar diferenças na simetria ao longo do tempo e entre indivíduos. Por outro lado, o índice proposto nesta Tese apresenta uma boa concordância e fiabilidade inter-sessão, e é sensível ao nível de assimetria tipicamente encontrado em sujeitos com um padrão de marcha assimétrico. Estas conclusões sugerem que este índice poderá ser uma ferramenta útil para a avaliação da simetria da marcha em contexto clínico

Alignment, Mass and Orthoses in Medial Compartment Knee Osteoarthritis

Biomechanical factors during locomotion are important contributors to knee osteoarthritis (OA). A better understanding of their potential role in intervention strategies is required. The overall purpose of this thesis was to examine the interaction between lower limb alignment and body mass on dynamic knee joint loading, and to examine the effects of knee and foot orthoses, in patients with knee OA. The thesis included three studies. Chapter 2 was a cross-sectional study using three-dimensional gait analysis and full limb radiographs in 487 patients. Using sequential (hierarchical) linear regression, results indicated a statistical interaction between lower limb alignment and body mass on the external knee adduction moment, a proxy for the load distribution across the knee and a strong risk factor for OA progression. The relationship between alignment and the knee adduction moment depended on mass, with a higher association observed in patients with higher mass. Chapter 3 was a systematic review with meta-analysis of the biomechanical and clinical effects of valgus knee braces. Data were extracted from 38 articles. When pooling data, standardized mean differences suggested that braces provided a statistically significant decrease in the knee adduction moment during walking, and in patient-reported measures of pain and function, with overall moderate effect sizes. Substantial issues related to appropriate dosage, patient comfort and compliance were also identified. Chapter 4 was a proof of concept study that tested the combined effects of knee and foot orthoses. Sixteen patients with varus alignment and medial compartment knee OA underwent repeated three-dimensional gait analyses with and without wearing a custom-fit valgus knee brace, custom-fit lateral wedge foot orthotic, and both. Results indicated that the combined use of the knee brace and foot orthotic provided greatest reductions in the knee adduction moment. Overall, the results of this thesis emphasize the importance of considering alignment and the distribution of loads across the knee during walking when developing intervention strategies for knee OA. The present findings provide rationale for future research examining the combined use of different interventions that target biomechanics, including orthoses tailored to maximize biomechanical effects while maintaining patient comfort

Quantification of knee extensor muscle forces: a multimodality approach

Given the growing interest of using musculoskeletal (MSK) models in a large number of clinical applications for quantifying the internal loading of the human MSK system, verification and validation of the model’s predictions, especially at the knee joint, have remained as one of the biggest challenges in the use of the models as clinical tools. This thesis proposes a methodology for more accurate quantification of knee extensor forces by exploring different experimental and modelling techniques that can be used to enhance the process of verification and validation of the knee joint model within the MSK models for transforming the models to a viable clinical tool. In this methodology, an experimental protocol was developed for simultaneous measurement of the knee joint motion, torques, external forces and muscular activation during an isolated knee extension exercise. This experimental protocol was tested on a cohort of 11 male subjects and the measurements were used to quantify knee extensor forces using two different MSK models representing a simplified model of the knee extensor mechanism and a previously-developed three-dimensional MSK model of the lower limb. The quantified knee extensor forces from the MSK models were then compared to evaluate the performance of the models for quantifying knee extensor forces. The MSK models were also used to investigate the sensitivity of the calculated knee extensor forces to key modelling parameters of the knee including the method of quantifying the knee centre of rotation and the effect of joint translation during motion. In addition, the feasibility of an emerging ultrasound-based imaging technique (shear wave elastography) for direct quantification of the physiologically-relevant musculotendon forces was investigated. The results in this thesis showed that a simplified model of the knee can be reliably used during a controlled planar activity as a computationally-fast and effective tool for hierarchical verification of the knee joint model in optimisation-based large-scale MSK models to provide more confidence in the outputs of the models. Furthermore, the calculation of knee extensor muscle forces has been found to be sensitive to knee joint translation (moving centre of rotation of the knee), highlighting the importance of this modelling parameter for quantifying physiologically-realistic knee muscle forces in the MSK models. It was also demonstrated how the movement of the knee axis of rotation during motion can be used as an intuitive tool for understanding the functional anatomy of the knee joint. Moreover, the findings in this thesis indicated that the shear wave elastography technique can be potentially used as a novel method for direct quantification of the physiologically-relevant musculotendon forces for independent validation of the predictions of musculotendon forces from the MSK models.Open Acces

Book of Abstracts 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization

In this edition, the two events will run together as a single conference, highlighting the strong connection with the Taylor & Francis journals: Computer Methods in Biomechanics and Biomedical Engineering (John Middleton and Christopher Jacobs, Eds.) and Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization (JoãoManuel R.S. Tavares, Ed.). The conference has become a major international meeting on computational biomechanics, imaging andvisualization. In this edition, the main program includes 212 presentations. In addition, sixteen renowned researchers will give plenary keynotes, addressing current challenges in computational biomechanics and biomedical imaging. In Lisbon, for the first time, a session dedicated to award the winner of the Best Paper in CMBBE Journal will take place. We believe that CMBBE2018 will have a strong impact on the development of computational biomechanics and biomedical imaging and visualization, identifying emerging areas of research and promoting the collaboration and networking between participants. This impact is evidenced through the well-known research groups, commercial companies and scientific organizations, who continue to support and sponsor the CMBBE meeting series. In fact, the conference is enriched with five workshops on specific scientific topics and commercial software.info:eu-repo/semantics/draf

Joint Loading Factors of Articular Cartilage Structure in Healthy and ACL-Injured Knees

Articular cartilage structure and chondrocyte health are sensitive and reliant on dynamic joint loading during activities. The risk of osteoarthritis (OA) is high after anterior cruciate ligament (ACL) injury, but mechanisms underlying its development are poorly understood. The overall goals of this work were 1) to determine the association between measures of individual and cumulative knee joint loading with T2 relaxation times in the knee cartilage of young individuals without injury and 2) to determine if these same knee joint loading factors are associated with cartilage T2 relaxation time one month after ACL injury. The central hypotheses was that lower measures of knee joint loading would be associated with higher (worse) T2 relaxation time throughout the articular cartilage of knees with and without ACL injury. Individuals without a history of knee injury and with an acute ACL injury in the past month served as participants for this study. Participants completed magnetic resonance imaging with T2 mapping, biomechanical gait analysis, and one week of accelerometry during daily living to measure T2 relaxation time, knee joint angles and moments, and daily physical activity levels, respectively. Individual loading factors and cumulative knee joint loading were correlated with higher T2 relaxation times in the articular cartilage of uninjured knees. Altered knee joint adduction moment impulse, less knee flexion excursion, and higher daily physical activity were associated with prolonged T2 relaxation time one month after ACL injury. Gait biomechanics and daily PA may be modifiable targets to alter OA development acutely after ACL injury

Wearables for Movement Analysis in Healthcare

Quantitative movement analysis is widely used in clinical practice and research to investigate movement disorders objectively and in a complete way. Conventionally, body segment kinematic and kinetic parameters are measured in gait laboratories using marker-based optoelectronic systems, force plates, and electromyographic systems. Although movement analyses are considered accurate, the availability of specific laboratories, high costs, and dependency on trained users sometimes limit its use in clinical practice. A variety of compact wearable sensors are available today and have allowed researchers and clinicians to pursue applications in which individuals are monitored in their homes and in community settings within different fields of study, such movement analysis. Wearable sensors may thus contribute to the implementation of quantitative movement analyses even during out-patient use to reduce evaluation times and to provide objective, quantifiable data on the patients’ capabilities, unobtrusively and continuously, for clinical purposes

Estimation and validation of temporal gait features using a markerless 2D video system

Background and Objective: Estimation of temporal gait features, such as stance time, swing time and gait cycle time, can be used for clinical evaluations of various patient groups having gait pathologies, such as Parkinson’s diseases, neuropathy, hemiplegia and diplegia. Most clinical laboratories employ an optoelectronic motion capture system to acquire such features. However, the operation of these systems requires specially trained operators, a controlled environment and attaching reflective markers to the patient’s body. To allow the estimation of the same features in a daily life setting, this paper presents a novel vision based system whose operation does not require the presence of skilled technicians or markers and uses a single 2D camera. Method: The proposed system takes as input a 2D video, computes the silhouettes of the walking person, and then estimates key biomedical gait indicators, such as the initial foot contact with the ground and the toe off instants, from which several other temporal gait features can be derived. Results: The proposed system is tested on two datasets: (i) a public gait dataset made available by CASIA, which contains 20 users, with 4 sequences per user; and (ii) a dataset acquired simultaneously by a marker-based optoelectronic motion capture system and a simple 2D video camera, containing 10 users, with 5 sequences per user. For the CASIA gait dataset A the relevant temporal biomedical gait indicators were manually annotated, and the proposed automated video analysis system achieved an accuracy of 99% on their identification. It was able to obtain accurate estimations even on segmented silhouettes where, the state-of-the-art markerless 2D video based systems fail. For the second database, the temporal features obtained by the proposed system achieved an average intra-class correlation coefficient of 0.86, when compared to the "gold standard" optoelectronic motion capture system. Conclusions: The proposed markerless 2D video based system can be used to evaluate patients’ gait without requiring the usage of complex laboratory settings and without the need for physical attachment of sensors/markers to the patients. The good accuracy of the results obtained suggests that the proposed system can be used as an alternative to the optoelectronic motion capture system in non-laboratory environments, which can be enable more regular clinical evaluations.info:eu-repo/semantics/acceptedVersio

Knee joint biomechanics after anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) is an important stabilizer of the knee joint. After ACL rupture, the knee joint has difficulty maintaining its stability; thus the patient often has to receive an ACL-reconstructive surgery to regain the knee joint functions. Unfortunately, traditional transtibial surgical techniques could not fully restore the normal knee joint kinematics during daily activities. Moreover, a higher rate of osteoarthritis was found from the ACL-reconstructed knees compared to the knees without a history of ACL-injuries. The reason for the increased risk of knee osteoarthritis is still unclear, and the pathologies due to abnormal knee joint kinematics remain controversial. The dissertation was to delineate the knee joint motion and loading after ACL-reconstruction. Thirty patients who received ACL-reconstructive surgeries using the traditional transtibial technique and 14 using the recently developed anteromedial portal technique were recruited from the same center (OrthoCarolina). Twenty healthy subjects without history of knee injuries were recruited as the control group. Human motion data and ground reaction force data were collected during level walking and downstairs pivoting using an optical motion capture system. Three-dimensional (3D) knee joint motions were determined from redundant markers using an optimization approach. The 3D knee joint moments and forces were calculated from motion data, ground reaction data by using an inverse dynamics model of the lower extremity. A finite element model was created, and the distributions of stress/strain within articular cartilage under physiological loading were estimated. The results from two groups of patients using different reconstruction techniques were compared. In the transtibial group, excessive internal tibial rotation (2° on average during stance phase), varus rotation and anterior femur translation (swing phase) were observed in the ACL-reconstructed knees when compared to the control group during level walking. The 3D knee joint motion following ACL-reconstruction was found to be influenced by the leg dominance. The motion and load in the uninjured contralateral knee were also affected. During downstairs pivoting, the normal varus rotation and adduction moment were not fully restored by the transtibial technique. Overall, the anteromedial portal technique improved the postsurgical knee joint kinematics by reducing the offsets in the internal tibial rotation, varus rotation and anterior femur translation during level walking. It also improved the adduction moment during downstairs pivoting. At the same time, the anteromedial portal technique may cause a flexion/extension deficit during the stance phase of walking. Results of finite element analysis demonstrated higher pressures within the medial femoral cartilage during the stance phase of walking; it also demonstrated that there is an increased knee joint laxity after ACL-reconstruction. The anteromedial portal technique was overall better than the traditional transtibial technique in respect to postsurgical knee joint compressive loading and contact pressure. The study provides evidence of the possibility by using anatomical single-bundle ACL-reconstruction technique to fight the knee joint osteoarthritis after ligament injury

Novel Research about Biomechanics and Biomaterials Used in Hip, Knee and Related Joints

Joint replacement is a very successful medical treatment. However, the survivorship of hip, knee, shoulder, and other implants is limited. The degradation of materials and the immune response against degradation products or an altered tissue loading condition as well as infections remain key factors of their failure. Current research in biomechanics and biomaterials is trying to overcome these existing limitations. This includes new implant designs and materials, bearings concepts and tribology, kinematical concepts, surgical techniques, and anti-inflammatory and infection prevention strategies. A careful evaluation of new materials and concepts is required in order to fully assess the strengths and weaknesses and to improve the quality and outcomes of joint replacements. Therefore, extensive research and clinical trials are essential. The main aspects that are addressed in this Special Issue are related to new material, design and manufacturing considerations of implants, implant wear and its potential clinical consequence, implant fixation, infection-related material aspects, and taper-related research topics. This Special Issue gives an overview of the ongoing research in those fields. The contributions were solicited from researchers working in the fields of biomechanics, biomaterials, and bio- and tissue-engineering