Weekly Update in lieu of Recurring Meeting of Cleveland Clinic Core Team
Date: March 21, 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 started testing samples from the 48 yr old specimen. She did four cartilage unconfined compression tests. Two tests on day 1 and one each on day 2 and and 3. The tests were conducted in saline and did not include ramp load-unload before-after preconditioning to compare test results with 40 yr old specimen, which were fairly repeatable. This set of tests were not as repeatable. From the thickness measurements and 'find contact' position values it appears that the sample did not recover even after left without load overnight (as evident from test 3 and 4). Also, on a visual inspection the superficial layer looked degenerated, which may have affected the recovery.
- Snehal took another sample from the neighboring location and tested under unconfined compression using phosphate buffered saline (PBS). There was one and half hour between test 1 and 2 on day 1 and it appears that the error was ~9%. The sample did not appear to have recovered completely (evident from find contact positions). Test 3 was conducted next day and thickness was measured again. Thickness difference was 2% between days 1 and 2.
- Protocol settings (strain, rate etc) were adjusted accordingly. Even with slightly increased thickness and resultant strain and strain rate values, the sample appeared less stiff but the error between test 1 and 3 (where sample rested and recovered overnight between tests) was lower, the repeatability was better (~6%). This is encouraging.
- Sample recovery appears to be essential in repeatable behavior. PBS and longer unload time between tests seems to aid the recovery. Note that solely implementing longer resting time did not appear to aid reasonable recovery of the sample on its own as seen in sample 1 results and therefore PBS use is recommended, especially for potentially degenerated samples.
- Snehal will conduct at least 3 more tests on this sample to study the trend over multiple days.
- Snehal will also test the updated preconditioning protocol next (with ramps before and after preconditioning), longer wait time between two tests on the same day (2 hours min) and remeasuring sample thickness.
- Data manuscripts.
- No progress.
- No progress.
- None noted.