Amniotic Membrane Supplementation in Rotator Cuff Reconstruction

Amniotic membranes have been of recent inquiry in the surgical world because of their composition of stem cells. These stem cells can differentiate into the desired type of cells in the body. In this study, amniotic membranes were placed on the insertion of the rotator cuff muscles after rotator cuff surgery to see how this affected recovery time. In order to determine this, the strength of the individual muscle fibers was determined using the single fiber isometric strength method. This method involves pulling out a single muscle fiber from a bundle of fibers obtained from the rat, tying it onto the apparatus and exposing it to high levels of calcium in order to allow for a contraction to occur. After determining the cross-sectional area and the peak isometric force, the specific force (the force per cross-sectional area) can be calculated in order to compare the relative strength of fibers from different samples. This study consisted of four different groups; uninjured control (no surgery performed), control repair (no amniotic membrane supplementation), injury only (no rotator cuff surgery performed), and experimental repair (surgery with amniotic membrane supplementation). There were six fibers obtained from each rat sample with 8 rats per group totaling 192 fibers. Once the specific force is determined for every group, comparisons were made to see if the amniotic membrane supplementation helped restore the specific force of the rats 4 weeks post intervention. This is applicable to human rotator cuff surgeries because it could help patients recovering from this surgery and decrease the recovery time. This would allow for these individuals to return to their normal activities more quickly. In addition, this method can be used in multiple different surgery sites to help improve recovery time.

Realities of Research

This project got frustrating at times because of the variable conditions of the fibers. There were some bundles that contained large, healthy fibers and some that contained extremely small and frail fibers (size comparison can be seen in images 1 and 2). While we did not know what groups these fibers were a part of because of the double-blind format, it was possible to infer which groups these fibers were from. Another interesting thing about this study is that it took three weeks to train for this technique. It started with learning how to tie the minuscule ties used to tie the fibers and then learning how to tie them on a practice machine. We practiced on separate machines because of the high probability we would break the real apparatus if we started on that. However, once data collection started, around 12-18 fibers were run each day and real progress was made. It was also interesting to see the variability of specific forces in a given bundle. This is something that we were not expecting, but was most definitely present. Luckily, the research question never changed, but there were many times that we would have to re-run fibers due slippage, ripping or any other issues that presented themselves.

The difference in cross sectional area for given fibers from different rats.










Day-to-Day Life of a Scientist

Life as a researcher was much more relaxed than I initially thought it would be. The arrival and departure time for each day was variable. While it was expected that you completed all of the work for the day, this could be done earlier or later in the day. This made it very low stress and everyone in the lab was extremely friendly and fun to be around. The best part of the research was definitely at the end of data collection when we were able to compare the specific forces and see if the amniotic membrane supplementation was effective. However, the worst part was definitely the struggles that I had with a specific rats sample that took me three days to get 6 good fibers run. I also had a great time in the collaborative lab meeting that was help in August with the entire research team. This gave an amazing opportunity to share results from multiple aspects of the project and see how all of the data fits together.

Jeffrey Kepple is a senior at Gonzaga University in Spokane, WA. He is a 2017 Undergraduate Summer Research Fellow (UGSRF) doing research in Dr. Chris Mendias’ lab at the University of Michigan in Ann Arbor, MI.  After graduating, he plans on pursuing an MD/PhD.

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