Recurring Meeting of Cleveland Clinic Core Team

Date: June 3, 2014

Time: 10:30 AM EST

Means: In person meeting

Attendees:

1. Ahmet Erdemir
2. Jason Halloran
3. Craig Bennetts
4. Snehal Chokhandre
5. Katie Stemmer
6. Robb Colbrunn
7. Tara Bonner

Agenda:

1. Discuss immediate action items from the last meeting.
2. Revisit joint testing coordinate systems.
3. Revisit anatomical imaging.
4. Discuss tissue testing progress.
5. Decide immediate action items for the next meeting.
6. Other.

Immediate Action Items:

• Jason
  • Finish registration marker error analysis and upload singular value decomposition (SVD) script.
• Tara
  • Provide detailed information on location of accessories and supplies to prepare extensor mechanism of the patellofemoral joint.
• Robb
  • Provide processing tools to move between "right knee abstraction" and "physical representation" of knee data collected during joint testing.
• Snehal
  • Write a Python script to read and plot tissue testing files.
  • Provide Martin Garon (Biomomentum Inc.) ACL data to illustrate the problem in displacement data collection.
  • Fine tune confined/unconfined compression and uniaxial tension protocols by further tissue testing.
• Snehal and Craig
  • Design an image-based thickness measurement system.

Notes:

1. Discuss immediate action items from the last meeting.
   • Jason uploaded the sphere fit algorithms.
   • Jason and Tara updated quadriceps tendon preparation procedure.
     • An image was uploaded of the setup and a description of how to prepare the tendon was added.
     • Tara will provide detailed information on location of accessories to prepare the extensor mechanism.
     • A description of the “tube” or cup used to contain the liquid nitrogen for tendon/clamp freezing during testing should also be added.
   • The lab setup is still ongoing.
     • The eye wash station should be setup this week. The tissue testing machine will be moved to the newa lab after that.
     • Manufacturing of the “tall” bath is still in discussion. There's some back and forth about whether the flat face will be glass or plastic. A decision should be made and documented so that this issue can move forward. Snehal will let Tony Shawan (prototype core manager) that glass is fine and he should finish the bath.
   • Elvis finished his testing last week and Snehal has all his data.
     • Preliminary results were briefly looked at and Snehal is working on a script to parse the data.
       • Essentially, they are very large files for each specific test with results for each loading cycle
         • populated in a serial fashion.
       • Snehal will create a Python script to read/plot the data for review.
       • The raw data was plotted and it is apparent the erroneous displacement data points were populating the results, which makes it difficult to decipher the real response.
       • The force results for a tension test also appear to have a large bandwidth for each loading cycle (around 6 grams), which is greater than the resolution (0.5 grams) of the transducer.
       • This data may be difficult to use.
       • Snehal will test the approach to data collection with a tissue test in the upcoming week(s).
       • Robb theorized there may be electrical noise in the results but this is yet to be determined.
       • Another ligament will be tested, with video included, to troubleshoot these issues.
   • Craig and Snehal worked on the thickness measurement approach using a foam sample.
     • 5 measurements were acquired using the optical approach and the constant pressure LVDT probe.
     • The LVDT measured thinner and both had similar variability (approximately 0.02 mm for 1 mm thickness).
     • The result is approximately a 2% error if the thickness is around 1 mm.
     • Softer tissues may exhibit more variability.
     • A specification for how to handle this measurement during testing needs to be developed.
     • Essentially, a jig to reliably hold the tissue sample and measurement apparatus should be designed and implemented, regardless of whether the optical or LVDT is used. In fact, during the first tests, both measurements may be used for redundancy.
     • A separate system, including a camera, stage, ruler and computer, will be configured for the optical measurement setup. During the upcoming troubleshooting, the heating system should also be included.
2. Revisit joint testing coordinate systems.
   • Robb provided a document covering the conventions used to describe the joint coordinate systems, and resulting differences between the right and left knee conventions. The group discussed the general approach for collection and reporting of joint kinematics/kinetics and established the sign conventions. The kinematics follow the convention of the Grood and Suntay convention whereas the kinetics is reported as forces and moments resulting in anatomical movements of tibia's motion, with axis orientations aligned with the tibia coordinate system. The distinction between "right knee abstraction" and "physical representation” was made. The robotics testing system treats all knees as right knees during joint kinematics/kinetics data collection (right knee abstraction). For left knees, post-processing of the data is necessary to return back to actual left knee coordinate systems (physical representation). For right knees, right knee abstraction and physical representation are the same. While the document reflects this, additional clarification will be helpful. Also, a second document will be developed to describe data processing to move between right knee abstraction and physical representation.
3. Revisit anatomical imaging.
   • Ahmet received a spreadsheet from Shannon from the imaging facility at the University Hospitals. Imaging parameters from previous imaging trials are provided in the spreadsheet. These parameters will be used to finalize the imaging specifications. Craig will also take a look at these settings to ensure they make sense.
4. Discuss tissue testing progress.
   • This agenda item was discussed as part of the discussions of the immediate action items from the last meeting (see above).
5. Decide immediate action items for the next meeting.
   • Action items were discussed and agreed on. See Immediate Action Items above.
6. Other.
   • Robb provided an update on the robotics joint testing system upgrades. Dylan is currently replacing the motors.
   • Tara updated the group on the gravity compensation issue of the robotics joint testing system. Apparently the issue is related to the fasteners not being tightened appropriately. The compensation algorithm will be retested for repeatability.