Recurring Meeting of Cleveland Clinic Core Team

Date: July 29, 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. Discuss pilot specimen testing outcomes.
3. Decide immediate action items for the next meeting.
4. Other.

Immediate Action Items:

• All
  • Update oks004 wiki page to provide information on specimen-specific experimentation.
  • Recommend changes in specifications based on oks004 testing experience in the oks004 wiki page.

Notes:

1. Discuss immediate action items from the last meeting.
   • All action items from the last meeting were incorporated to preparations for complete testing of a specimen. See more details in the next agenda item.
2. Discuss pilot specimen testing outcomes
   • Ahmet asked everyone to update the oks004 wiki page to reflect what was learned during the complete pilot test, especially related to their specific tasks. This page will document any deviations from the existing specifications. It will also include recommendations by the team members, and allow the community/group to decide the changes that may be needed in the specifications. Ahmet already added protocol deviations as well as additional notes. One time deviations may happen, and they should be noted in each specimen's page. For example, for oks004, the tibia was mounted “up”. The team can discuss if this is a one time deviation or whether it should be adapted as a change in the joint testing specification.
   • Snehal has started updating her sections in the experimentation summary of the oks004 knee. The oks004 knee effectively serves as a pilot test as it is outside the desired specifications for actual Open Knee(s) specimens.
   • Craig noted that by filling in the lead and supporting team members for each task in oks004 page, all members would know where they need to contribute. In return, the group spent some time documenting each of these sections by assigning them to the appropriate team members. Everyone has the task of updating their relevant sections.
   • The team briefly discussed options for tibia and femur registration, which includes rapid prototyping of uniform spheres, as opposed to using the existing hollow spheres.
   • The group discussed specimen dissection to follow up joint testing with tissue testing. As Snehal noted, the fellow, who helped with tissue testing preparation, managed to excise the MPFL and medial and lateral capsule for future testing. He also confirmed that the specimen appeared “healthy” with no obvious signs of degradation.
   • Major hurdles and specific deviations during the test were discussed.
     • General deviations have already been noted, including potential solutions that were implemented “on-the-fly.”
     • Specific to preparation, thawing required approximately 22 hours.
     • One issue that was not elaborately discussed in the specifications was the fixation of the fibula. During the testing, the fibula was secured to the tibia by passing a drill bit through both bones after the foot was removed. While it is advisable to do this before the foot is dissected (in order to accommodate natural alignment of fibula and tibia), this may be problematic as the imaging may prevent the use of a metal drill bit. Various potential solutions were discussed, which included plastic fixation for imaging replaced by a metal screw before the actual testing.
     • Specific drill bit sizes to prepare bones to secure registration and optotrak markers were not noted in the specifications. This resulted in wasting of time to determine pilot hole sizes that were needed to place various plugs and registration spheres.
     • Snehal noted that the image collection of specimen preparation for imaging needs to be updated to reflect what was actually done before the testing; in particular, making sure that patella registration marker assembly is placed.
     • The largest deviation in the tibiofemoral testing was mounting the tibia up, as opposed to the femur. This allowed direct measurement of the tibia reactions, as opposed to measuring reactions through the flexion axis (includes resolution through two transducers).
     • Regarding imaging, at a first glance, the images look acceptable. Specific documentation concerning the “localizer” and setup of the location of the field of view (e.g. the center of the image set) needs to be documented. This includes making sure the registration markers are included in the general imaging set (the isotropic 0.5 mm x 0.5 mm x 0.5 mm image acquisition).
     • For patellofemoral testing, the knee had to be assembled on the robot by orienting it around the superior-inferior axis so that the quadriceps actuator acted directly above the patella. Digitization of this line of action was not well documented in the specifications, which needs to be incorporated. Ahmet noted that using one perssure sensor per knee is appropriate, especially given the trouble putting the sensor in the joint. Using the same sensor again may be risky. The sensor that was used for the pilot testing should probably be re-calibrated to compare with the pre-testing calibration results (by applying both calibration files to the same raw sensor data). Ahmet is inclined to keep the current specifications and try this protocol again on the next knee. The current approach needs to be documented in more detail on the wiki.
     • Snehal has 30 tissue tests to perform, which encompasses 22 samples (confined and unconfined compression tests on the same samples). Snehal noted that the cartilage was harvested on the following day, which was not ideal. Snehal asked that we start earlier to avoid keeping the specimens in the fridge for another day.
     • Of note, tendon samples from the foot were acquired and tested along the timeline of oks004 testing. These samples were exposed to similar environmental conditions. A simplified loading regime (a shortened stress relaxation test) was used to characterize these tissues compressive behavior along the transverse axis. If drastic changes are noted, this may warrant a study focused on the influence tissue degradation on mechanical response.
     • For thickness/width measurement of tissue samples, Snehal noted we still do not have an acceptable” optical measurement approach. This data will compliment the robot data as well as provide an estimate of the Poisson's ratio and tissue sample cross-sectional area, by acquiring tissue width and thickness.
     • Snehal still finds it challenging to fit all required tests for a single specimen in one day, especially for the compression tests. The result is another day out of the freezer, which is not ideal. Snehal will document the required time for each test so that they can be fit into a single day per sample. Logistics will be worked out but options include using multiple personnel (as Tara noted) to support the testing.
   • Including the offsets in the left to right knee conversion for kinematics description is being worked on by Robb. Ahmet noted that a “sanity check” should be performed to verify matrix results yield expected results, e.g. varus prescription actually moves a knee in varus, etc. Coordinate frame verification needs to be performed first for the J2C data before it is published, and then for the pilot testing (oks004).
   • Ahmet uploaded most, if not all, of the oks004 data to the Midas platform. It's relatively unorganized at this point but it will be cleaned up as the data is used.
3. Decide immediate action items for the next meeting.
   • Action items were discussed and agreed upon. See Immediate Action Items above.
4. Other
   • None noted.