Week 7

The last week of the immersion program has come to an end, and it was definitely one of the most productive weeks here in NYC. All the preparations----IACUC protocol, surgical and rodent cadaver trainings-----payed off as we finally went in to the OR in the animal facility to practice ACLT on live rats. I am very glad that we were able to do this, as I realized that cadaver practices cannot capture the scope of complications on live animal surgeries. I learned how to manage and monitor the depth of anesthesia, when and where to administer pain killers and antibiotics, and all the little details that you can only pick up in a real OR (such as how to effectively maintain sterile barrier, how to minimize pain and discomfort of the subjects, and etc.). One thing I overlooked when I was preparing myself for the live animal training is the importance of monitoring the depth of anesthesia. The depth of anesthesia affects the heart rate and respiratory rate of the animal (the respiratory rate is actually one of the ways to monitor depth of anesthesia), and thus affects the bleeding when incisions are made. Unlike cadavers where there are no bleeding, the live animals can bleed excessively if it is heart rate has not slow down properly from anesthesia, resulting obstructed views by the blood and thus longer and more complicated procedures.

The other good news it that our closed PTOA apparatus is now functional. After numerous iterations and trails and errors, we have finally achieved control speed, displacement and alignment, and ease of operation. As it turns out, the ease of operation was actually more changeling than we originally thought. Because we were modeling our system based on the previously existing PTOA apparatus in rats, we often forget how small mice are. For example, mounting the tibia to the feet clamp is a easy task on rats, but it has proven to be much harder on mice which are around ten times smaller. The size limited the space we can operate, and many mechanisms of stabilizing ended up being too bulky to be practical. Luckily, we gotten it almost figure out by Friday and proceeded to testing on some cadaver mice. Our measurements agrees with the mechanical testing of ACL and the data from the manual methods. However, with manual methods when the force is greater than 10N the PCL are often also ruptured. With our device, we can exert >20N of force and rupture the ACL only, as a result of the controlled displacement. This is great because we know the strength of ACL varies greatly from animal to animal, and with the apparatus, we don’t have to sacrifice the ones with stronger tendons just because we cannot rupture it properly. The ongoing theory of why the manual method always rupture the PCL with the ones of greater force is that once the ACL is ruptured the human hand will accelerate due to the sudden decrease of resistance and hit the PCL. The great the force requires to rupture the ACL (tougher ACL), the greater this acceleration will be and the more likely the PCL will be ruptured. This is precisely why we went to the more controlled methods with a loader in the first place----with a control displacement, no matter the force needed to rupture the ACL, the PCL will remain intact as the loader will never reach it.

I am very happy that all my goals have been accomplished. I am glad that I was able to challenge myself and try new things, both in lab and in life. I had a fantastic summer here in NYC and I will certainly miss the city. In truth, I am already missing it as I am typing my last immersion blog in Newark Airport, but who knows, since my flight has already been delayed for four hours I may never get to leave here after all.