Monday, July 12, 2010

Katie - week 4

Week four of summer immersion involved working on my project extensively. For this project, I am working with both Dr. Wright and Dr. Padgett to determine the wear of total knee arthroplasties that have been retrieved. Another medical student and I are analyzing 38 knee implants, all of a similar design, to compare to previous data on "mobile bearing" knee implants. Although the mobile bearing implants are supposed to provide more movement, less shear forces, and less pain for certain subjects, there is a huge concern with wear as the piece that can rotate will scratch and wear much more easily than a stationary piece.

This project involves dividing the knee implant into ten regions on either side, and then grading each region according to seven different wear modes: burnishing, pitting, scratching, abrasion, delamination, third body debris, and surface deformation. By looking under a 10x dissecting microscope, the wear is examined and recorded on a scale of 0-3. This week I spent a great number of hours analyzing about 1/3 of the implants. I am hoping that in the next coming weeks I will finish the evaluation and be able to compare the data to previous data.

Also this week, I gained a lot of experience on the 5th floor of Caspary with immunohistochemistry of estrogen receptor alpha. Because of my research at Cornell, this technique is very relevant and will be useful for me to learn for my PhD. I have never dealt with immunohistochemistry before, and so this was a great experience for me. Estrogen receptor alpha plays a major role in bone formation and maintenance through estrogens, androgens, and SERMs.

As usual, I attended both Dr. Boskey and Dr. Bostrom's lab meetings, and attended the total arthroplasty grand rounds. I still am fascinated at how much of an art surgery is. Many of the fellows and attendings use different surgical techniques. For a half an hour, only one patient was discussed! During this time, the leader of the meeting was quizzing the residents, and also some of the attendings were asking questions and sharing their ideas, such as the weight limit for a ceramic hip implant, the age at which a metal on metal implant might be a possibility, and when bone grafts are often used. During grand rounds, I get a lot of experience with interpreting x-rays. I am beginning to understand how to look for loosening of total hip and knee implants, indicated by the osteolysis around the stem. However, it can be tricky to see a misaligned implant, and the angle of extension or flexion and the angle at which the x-ray comes through the leg play huge roles on interpreting the x-rays. Sometimes an implant may look slanted, but it is only due to the angle of the x-ray or leg. A lot more goes into reading x-rays than I would have initially thought!

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