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Multiscale computational modelling for natural hip biomechanics and tribology

Periodic Reporting for period 1 - MSCHIPBIO (Multiscale computational modelling for natural hip biomechanics and tribology)

Período documentado: 2017-06-01 hasta 2019-05-31

Joint diseases are the most common health problem, afflicting over 100 million people in the EU Countries. The underlying mechanism of the joint disease has not been fully understood, but it is well recognized that the changes in the mechanical environment of joint and articular cartilage are important contributory factors. In addition, although joint diseases are widespread, the optimization of the patient management - predicting disease progression, selecting therapy, monitoring response, developing new treatments - presents significant challenges. All of these require an in-depth knowledge of the functional biomechanics and tribology of the articular cartilage for improving our understanding in joint disease mechanism, and require a robust, effective approach to gain this knowledge, to diagnose or prognose joint disease, to plan treatment and prevent disease, and to support the development of new issue sparing substitution and regenerative treatment.

The overall objectives of the project are:
(1) Develop a patient-specific musculoskeletal multibody dynamics model (MBD) of the human body;
(2) Develop a patient-specific finite element (FE) model of the natural hip joint, which enable to integrate the solid mechanics of the cartilage and the behaviour of the fluid flow within the joint into one model;
(3) Develop a multiscale approach to couple these two levels of model;
(4) Apply the model to simulate and investigate the temporal variation in biomechanical behaviour of the articular cartilage under physiological loading conditions during seven daily activities.

The action was carried out in the Institute for Biomechanics at ETH Zurich in Switzerland. An advanced multiscale approach for coupling a MBD model of the human body and a FE model of natural hip joint was developed. The biomechanical and tribological behaviours of the articular cartilage under physiological loading conditions for seven daily activities were investigated. During the research action, the fellow has gained substantial knowledge in his area of expertise and improved his personal capacities and skills through a series of training and research activities.
The following works were performed during the Fellowship:
(1) A patient-specific musculoskeletal multibody dynamics (MBD) model was developed using the AnyBody modelling system. The hip contact forces during seven daily activities (i.e. normal walking, ascending stairs, descending stairs, lunge, squat, standing up and sitting down) were predicted;
(2) A patient-specific FE model of the natural hip joint, which integrated the solid mechanics of the cartilage and the behaviour of the fluid flow within the joint, was developed using the FEBio software system;
(3) A multiscale computational modelling to couple the MBD model of the human body and the FE model of the natural hip joint was developed through a python script. The modelling was then applied to seven daily activities to investigate the biomechanics and tribology of the articular cartilage, in terms of the contact stresses, fluid pressures, stresses and strain within the cartilage over 80 cycles for each activity.
(4) A series of training, research and outreach activities have been carried out to disseminate and exploit the research outcome and improve the fellow’s capacity.

The main results:
(1) An innovative and advanced multiscale computational modelling pipeline to couple a MBD model of the human body and a FE model of the natural hip joint was developed in the project.
(2) The patterns of peak contact stresses and peak fluid pressures within the cartilage follow the patterns of the hip contact forces during a cycle of each activity, with higher peak contact stresses and peak fluid pressures predicting during ascending and descending stairs, and lower contact stresses and fluid pressures predicting during standing up and sitting down activities;
(3) For all the activities considered, when the contact areas approach to the rim of the cartilage layers, contact stresses and fluid pressures decreases over a long period due to the fluid flow out from the cartilage, leading to decreased fluid support;
(4) On the contrary, when the contact areas occurs at the center of the articular cartilage, the contact stresses and fluid pressures increase over a long period due to the creep of the fluid and solid matrix, and potentially “ploughing” effects.

Exploitation:
The developed multiscale computational modelling, when applied to the images of patients, can be used for treatment planning and joint disease prevention, diagnosis, and prognosis, which will address the rapidly growing demand for computer-aided medicine and personalised treatment within the healthcare sector.
The approach can also be used as an effective tool for pre-clinical testing and assessment, designing and optimising prosthetic products and new biomaterials.

Dissemination:
(1) The results of the project were submitted and presented in two international conferences, and will published in two peer-review journal papers.
(2) The developed multiscale computational modelling was presented in a summer workshop (Image-based Biomedical Modelling) at University of Utah in the USA in 2017, and in the 6th MCAA General Assembly and Annual Conference in Austria in 2019;
(3) The developed multiscale computational modelling and results were presented at University of Sheffield and Middlesex University in the UK, at Southwest Jiaotong University in China and at DePuy Company in the UK between 2017 to 2019;
(4) The FE technology for modelling the articular cartilage was demonstrated to the Master students in a master module.
Progress beyond the state of the art and expected results:
This research for the first time simulated the non-linear, time-dependent and solid-interactive properties of the three dimensional articular cartilage in a human joint over a long period during different daily activities. The research for the first time coupled a MBD model of human body and a FE model of natural hip joint with biphasic cartilage, which enable the hip contact forces, the solid mechanical of the cartilage and the behaviour of the fluid flow within the joint to be examined under physiological loading conditions for a same specific subject.

Potential impacts:
With respect to the society, the results of the research will improve our understanding of how the joint behaves under different conditions and the pathology of joint diseases, and will help the design of targeted interventions, which in the long-term could be beneficial for the healthcare sector and therefore the patients.
With respect to the economy, considering the universality of the joint diseases and the associated costs, the burden of the joint diseases placed on the healthcare sector is massive. If the research could identify specific biomechanics loading patterns that reduce the incidence to cartilage damage progression, and reduce the response of patients to milder and cheaper treatment, it is conceivable that low-cost physiotherapy protocols offered as coadjuvant of the mild anti-inflammatory therapy would considerably reduce the burden of disease in the EU.
With respect to the industries, the long-term beneficiaries of the research will be the manufacturers of orthopaedic devices and biomaterials to treat diseased joints and deliver improved and safer materials and interventions.