Weekly Update in lieu of Recurring Meeting of Cleveland Clinic Core Team
Date: April 11, 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.
- 1. Snehal conducted week long unconfined compression tests on 2 tibial cartilage samples taken from neighboring locations. This set differs from the previous weeks' set in that, 0 to 15% strain at 20%/s load-unload ramps were applied before and after preconditioning. As the previous set demonstrated repeatability with 6-8.5% error, it was expected that this set would have similar repeatability characteristics.
One sample had a repeatability error ~15 % and the second had ~50%. However, in the second sample test set, the first two tests started at >50g force instead of 10g, the position for which is found from 'find contact' protocol as a starting position to apply desired strains. This was an anomaly and was not as pronounced in other tests. This may have amplified the error, as the last three tests were fairly repeatable.
- Note that for the 'find contact' protocol, the force data is filtered and for 'stress relaxation', it is not and therefore may read higher when unfiltered at the same indenter location. However, the position at which the force starts to increase is the same regardless.
- Ahmet suggested that in post-processing instead of choosing the 10g force position as the starting thickness/position, pick the position at which the indenter makes contact with the sample/ when force starts to increase. This only changes how the data is processed. Snehal is updating the tissue data analysis script to accommodate the recommendation.
- Snehal is currently testing effects of multiple freeze-thaw cycles on cartilage properties by testing a sample under unconfined compression over a week by freezing it every day after testing.
- Data manuscripts.
- No progress.
- No progress.
- None noted.