BIE6433 Computational Biomechanics of Musculoskeletal

System (15 credits, Level 7)

Aim

The aim of this project (100% of your module mark) is to estimate the bone strength (i.e., failure load) of either the left or the right proximal femur of one elderly patient and relate the results to the likelihood of bone fracture.

Outline

A 73-year-old, female patient has presented in the hospital for clinical investigation of suspected osteoporosis. The patient weight is  79kg, height is 161cm and her T-score (measured by Dual-energy X-ray absorptiometry) is -1.2. As part of her   clinical examination, a set of full thigh-length CT scan was collected for both the left and right femurs. The fully anonymised CT scans (VTK file) are provided to you (local ethics approval has been obtained from the Sheffield Teaching Hospitals).

In addition to the routine clinical examinations, the clinician has asked an engineer to perform a quantitative finite element analysis (FEA) of the bone strength of this patient to provide additional information on their risk of femoral fracture.

You need to examine the literature on osteoporotic fracture and FEA to review a range of modelling approaches for this problem and critically compare them in your report, before choosing the most suitable modelling approach (i.e.,  boundary  constraints,   loading conditions, etc.) for your assignment.

Your task, as the engineer in charge, is to:

a)   generate a suitable FE model of the proximal femur (do NOT need to segment the entire shaft) based on the CT scans. (The computer lab tasks will guide you through the  creation  of a  personalized  proximal  femur  model  based  on  CT  scans  that contain derived material property. See Lab materials on Blackboard.).

b)   simulate in the computer, a quasi-static sideways fall loading condition (see Fig.

1) using the most suitable boundary constraints to predict the bone strength for either the left or the right proximal femurs of this patient.

c)   compare your results with the previous literature you have examined.

d)   discuss the validity and limitations of your approach.

Fig 1. An illustrative diagram showing a protected sideway fall conducted in a lab.

Make sure that you list all modelling assumptions. Justify your choice of methodology and parameters.

The computer lab handouts (available on Blackboard) are based on ITK-snap and ANSYS  software  packages.  The recommended  FE  software  package to use is ANSYS,  either  Workbench or Mechanical APDL. If you are new to FE and ANSYS, we have provided the Level 3 Fundamental FEA materials (pre-recorded lectures on Blackboard under  Background knowledge) for you to catch up on the fundamentals. You can also ask us questions during the computer labs, which will be led by the lecturer and GTAs. In addition, there are some links (below) to useful online resources that demonstrate the  use  of  ANSYS in various FE applications:

https://courses.ansys.com/ https://forum.ansys.com/

https://www.ansys.com/academic/students/student-teams

Structure of report

Your report should have a maximum of 3000 words (excluding tables and list of references, but including figure/table captions), no appendix is allowed. You should use a minimum  font size of 11 with 2 cm margins. The report should be no longer than 13 pages (excludes  Cover Page and the List of References). Note that any extra pages will not be read. The  report should be submitted via Turnitin by noon Wednesday 11th December UK time.

The  standard   University  penalty  (refer  to  your  student   handbook)  applies  for   late submission. If the use of unfair means is confirmed, the relevant sections will receive a 0 mark and your name will be reported to the Department, who may carry out further disciplinary actions.

Your report should consist of the following main sections: introduction, a brief literature review, methods, results, and discussion.

• Introduction: This should consist of 1 paragraph, it should be clear and concise, and set the scene.

• Literature review: This section should provide a critical review to the range of modelling  methods  used  in  the  literature,  summarizing  their  advantages  and disadvantages,   and   explain   how   they   help   you   determine   your   proposed methodological approach.

• Methods: This  section  should  provide  a  clear  and  concise  description  of  the  methods used for modelling, with appropriate use of figures, tables and equations. List all assumptions (with justification) and  provide  references to any external  parameters used. The pre-processing steps (segmentation and mesh generation)  should  be brief (half  page to  one  page  long)  as the  process  has  already  been  provided  to  you.  Detailed  description  should  be  provided  for  the  type  of  displacement and force boundary conditions used in the FE simulation.

• Results: This  section should clearly describe the  results  obtained from the  FE simulations with illustrated figures and tables. Each figure and table should have informative captions.

• Discussion: This  section  should   provide  a  structured  discussion  with   logical presentation of your arguments, quoting both your results and the literature for comparison on model predictions. Your discussion should demonstrate innovative thinking and critical analysis and show understanding of the wider engineering context.

• References: The School does not have a specific requirement on the referencing style.  Therefore, you can choose any standard referencing styles, e.g.,  IEEE, Harvard, etc.

Learning outcomes assessed

• A1. Apply fundamental laws and principles of physics and/or engineering to

medical applications, some of which are at, or are informed by, the forefront of the discipline.

•    A2. Formulate strategies to solve complex problems in physics or engineering using a variety of experimental, analytical, design, statistical, mathematical and/or computational techniques.

•    A7. Demonstrate a critical awareness of the role of medical physics and/or biomedical engineering in medicine considering the technological, social and ethical aspects of the field and its development.

•    A8. Communicate scientific concepts to a range of audiences in a concise, accurate and informative manner, leading to the presentation of logical conclusions at a level appropriate to the audience.

•    A9. Manage their own learning and make selective use of a variety of resources including appropriate texts, research articles and other primary sources in their work.