Tutorial A: Finite Element Modelling to Predict Joint Stress
Chair: Rajshree Hillstrom (Anglia Ruskin University)
Osteoarthritis (OA), the number one cause of disability, exceeds 1% of the gross national product in both the UK and US and is increasing in prevalence as the population ages and becomes more obese. Excessive stress damages tissues within the joint, irrespective of the specific biomechanical etiology, and is considered a risk factor for OA. Hence, it is important to monitor joint stress. However, stress cannot be measured in vivo. In vitro experiments are expensive and may not accurately represent in vivo tissue properties. Finite element modelling is a useful computational method to predict joint stress before and after surgical interventions. This is a powerful tool to investigate the impact of surgical procedures on joint stress. The effect of factors, such as tissue geometry, material properties, type of activity and loading conditions, which could affect joint stress, may be investigated in the model.
When modelling human tissues, assumptions are made, for example on tissue material properties, which are subject specific and challenging to measure non-destructively. Sensitivity analyses are conducted to identify and simulate, with higher accuracy, those material properties that drive changes in stress magnitude. In this tutorial, participants will use FEBio finite element software, learn how to create simple finite element models and analyse joint stress. Participants will also have the opportunity to work with a first metatarsophalangeal joint finite element model to investigate the effects of different tissue material properties, foot types, and surgical interventions on joint stress.
Dr. Howard Hillstrom (Hospital for Special Surgery) will introduce the application of finite element modelling and the clinical rationale for its use, based upon his 90 studies in lower extremity biomechanics, including the assessment of foot type and musculoskeletal pathology, employing experimental and computational approaches. This introduction will include contemporary examples of biomechanical problems that could be addressed, using finite element models.
Dr. Rajshree Hillstrom (Anglia Ruskin University) will present a step-by-step method for developing a simple finite element model of a joint, using FEBio software. This will include creating and meshing simple geometry representing joint tissues, assigning tissue material properties, boundary conditions to simulate tissue interactions, loading conditions and to predict joint stress. During this hands-on session, participants will develop their own finite element models and run analyses. Dr R Hillstrom will then explain how to develop anatomically complex models. Participants will split in groups and solve for stress in the 1st metatarsophalangeal joint for different tissue properties and surgical corrections.
Mr. Oliver Morgan (Anglia Ruskin University) will assist participants with troubleshooting any problems during the hands-on aspect of this tutorial. He will make sure that FEBio is running smoothly on either windows or mac laptops and that participants have all the supporting files to participate in the tutorial.