Weekly Update in lieu of Recurring Meeting of Cleveland Clinic Core Team
Date: February 07, 2017
Provided by: Snehal Chokhandre
Ongoing Action Items:
- Review drafts of data manuscripts for submission.
- Complete studies for tissue testing reproducibility.
- Continue tissue testing of Open Knee(s) specimens.
- Continue segmentation of Open Knee(s) specimens.
- Tissue testing.
- Snehal tested a cartilage sample under unconfined compression over 4 days (8 tests total). The cartilage strip from which the sample was taken was frozen once the sample was punched out. Within a day, two tests were conducted with an hour wait time between them. The preconditioning protocol for these tests incorporated a ramp load -unload cycle before and after 1000 preconditioning cycles (15% strain at 20%/s). It appears from the stress relaxation data that the sample progressively got stiffer. The sample does not seem to have recovered even after unloading over night (as indicated by first test on the day 2,3 and 4). For details check dashboard in ["Specifications/ExperimentationTissueMechanics"].
- To assess whether this stiffening is a result of the ramp load unload cycles in updated preconditioning, another sample was taken from the cartilage strip and tested with previous preconditioning protocol. Two tests were conducted with an hour between the tests. The tests were not repeatable.
- Another sample was taken from the cartilage strip (at this point frozen-thawed 4 times) and the same test was repeated. The tests were reasonably repeatable.
- These samples were obtained right next to each other and still demonstrate different recovery behavior under the same testing conditions. The only difference was the sample thickness. The first sample was 1.81 mm thick and the repeatable sample was 2.4 mm thick.
- Snehal speculates that location specific degeneration might be causing the sample to not recover and saline solution may further be dehydrating the degenerated sample. To further explore this, she will tests samples in phosphate buffered saline (PBS) which has the same osmolarity and ion concentration as the synovium in the human body. Use of PBS may help in recovery.
- Ahmet suggested that multiple tests should be conducted on a rubber sample to ensure that the variations or non repeatability is not coming from the testing system or the test protocols but solely from the sample itself. Snehal will conduct 8 tests on a rubber sample with updated preconditioning protocol (with ramp before and after 1000 preconditioning cycles).
- Ahmet also suggested Snehal to check the ramp rates applied are same as the expected rates. Snehal mentioned that the applied rates are within 1% of the expected rates.
- Data manuscripts.
- No progress.
- No progress.
- None noted.