Week 3: Wedding this weekend!

This week, I was introduced to avascular necrosis (AVN) in the clinic. Avascular necrosis is the death of bone due to an insufficient blood supply. The first patient had been on a high steroid regimen to treat his ulcerative colitis, a chronic inflammation of the digestive tract. The long-term steroid use lead to AVN in his distal femur. I was not familiar with how steroid use induces AVN but it seems that many factors ultimately contribute to vascular impairment. The treatment plan involves an approach which incorporates a bone marrow transplant into a subchondroplasty. Developed by Zimmer, the subchondroplasty procedure allows a calcium phosphate substitute to be delivered to the site of bone marrow lesions. This substitute can also be used as a carrier for autologous stem cells from bone marrow which are a more pathophysiologic approach to treating AVN. Alternatively, AVN patients can undergo core decompression, in which a small piece of bone is replaced with a vascularized graft. This, however, is a temporary solution as I learned from observing the second AVN patient. She presented with AVN of the femoral head due to Thalassemia. In other words, she has some abnormal formation of hemoglobin, resulting in improper oxygen transport and destruction of red blood cells. Dr. Lane recommended that she undergo a hip replacement considering she was already 66 years old. The replacement would last the rest of her life and eliminate the need to undergo a second surgery once the benefits of core decompression were gone (1-2 years).

At the metabolic bone meeting on Monday, Dr. DiCarlo spoke more on the subject of combined drug treatments for osteoporotic patients. A few points stood out during that meeting. First, he highlighted the deposition of osteoid by osteoblasts occurs in a directional and layered manner, going against the simplified remodeling schematic presented in many animations and textbooks. Next, Dr. Lane asked if there is a way to determine whether particular osteoblasts will become osteocytes. Dr. DiCarlo pointed out that it could be a random process but the answer is unknown. Finally, although combination treatments seem promising, more animal studies need to be done to conclude the benefits and deterrents at different anatomical regions. Cortical and trabecular bone respond differently to these medications and so it is unlikely that all bones respond the same way.

I was also able to clarify my research responsibilities with Dr. Lane. I will be performing a case study on the previously mentioned patient with a Stanmore extendible prosthesis. The next time he comes to have a lengthening procedure done, he will be sent to HSS for a functional assessment. I hope to tag along so as to gain additional perspective on the rehabilitation process. We will consider his current function and the unique considerations for his customized prosthesis. This also will pave the way for easy follow-up in future months and years.