Recurring Meeting of Cleveland Clinic - University of Utah

Date: October 22, 2014

Time: 2:00 PM EST

Means: Conference call

Attendees:

1. Ahmet Erdemir (Cleveland Clinic)
2. Ben Ellis (University of Utah)
3. Steve Maas (University of Utah)

Agenda:

1. CMBBE 2014 update.
2. Update on feature implementations.

   1. In situ strain - http://wiki.simtk.org/openknee/Febio/InSituStrain

   2. Set definitions - http://wiki.simtk.org/openknee/Febio/SetDefinitions

   3. Connector elements - http://wiki.simtk.org/openknee/Febio/RigidBodyMotions

3. FEBio issues during simulations.
4. Decide action items for next meeting.
5. Other.

Immediate Action Items:

• Cleveland Clinic (TBD)
  • TBD
• University of Utah (TBD)
  • TBD

Notes:

1. CMBBE 2014 update.
   • Ahmet and Steve iterated over CMBBE 2014 discussions. In terms of defining mechanical joints/connectors, kinematic constraints (relying on penalization of deviation from the constraint) will be implemented. Steve will first go through Gerard Ateshian's code to familiarize himself with the formulation. In the long term this feature will resolve current issue with FEBio version 2.1, which does not allow prescribing flexion while setting other rotations free. Steve may need to find an intermediate solution for this.
   • Steve provided a presentation of the in situ strain feature at CMBBE 2014. This work is essentially complete. Ahmet iterated the need for a synergistic project where in situ strains may be calculated through an inverse analysis. In situ strain can be obtained experimentally for medical and lateral collateral ligaments (as Ben noted) but this may not fit the logistics of Open Knee(s) whole experimentation workflow. Additionally, an experimental approach will still be problematic for cruciate ligaments. Inverse analysis may be useful to provide a reasonable estimate of in situ strains from known ligament (or joint) forces and moments. This will likely be an ill-conditioned optimization problem but may be worth exploring further. Ben will try to check their medial collateral ligament data in that regard.

   • As discussed by Ahmet and Steve at CMBBE 2014, set definitions were implemented for both input and output files. Nonetheless, there is not an easy way to test the utility of those tests at the output file end. Steve will add support in PostView to accommodate browsing/visualization of sets. In additions, he may be able to implement support in the input file format to request output in human readable form for any desirable set.

2. Update on feature implementations.
   • TBD
3. FEBio issues during simulations.
   • TBD
4. Decide action items for next meeting.
   • TBD
5. Other.
   • TBD