Week 4

A lot of interesting things happened this week. On Tuesday I met with Dr. Dempster at Helen Hayes to go over some of the details of my project. I will be investigating whether the anabolic effects of parathyroid hormone (PTH) treatment are different under tensile loading versus compressive loading. I will be looking at histomorphometry data from the femoral necks of patients who underwent a total hip replacement after being treated with PTH or a control. The femoral neck provides a good platform to study how mechanical environment influences the effects of PTH because it is essentially under bending, with a tensile side and a compressive side.

On Wednesday I went with Aaron to shadow Dr. Spector in the OR. One of the patients required a split thickness skin graft to cover a large wound on her buttock. I always pictured skin grafts to be much more substantial, but the graft was extremely thin. The instrument to remove the skin reminded me of a cheese slicer/grater, and then they used another instrument similar to an old clothes wringer for drying clothes to perforate the skin before grafting it.

Thursday was a big day in the OR with Dr. Bostrom. He had only scheduled one case for the whole day (even though he ended up also doing a hip revision). The patient was in a car accident back in 2004 that broke both his tibias and caused traumatic brain injury. His left knee is essentially fixed at about ninety degrees due to disuse, scar tissue, and potentially some fusion of the joint. Dr. Bostrom replaced his right hip about a year and a half ago. On his left proximal femur, he had severe heterotopic ossification that needed to be removed, and his hip and proximal femur needed to be replaced. The problem was that the bone had formed very close to the important blood vessels in the groin, so a vascular team was brought in to help (Dr. Connelly). The first incision was more anterior in order to remove the majority of the bone, while the second incision for the implant was posterior-lateral. The amount of bone that was removed was incredible. They just kept pulling huge chunks of bone out of the incision. It's not entirely known what causes these ossifications to form. It could be something on the neural side, where some chemical signal is stuck in "on" or there is a miscommunication following some minor damage to the bone that causes excessive modeling, or something else altogether.