Orthopedics This Week—March 20, 2014
Geoffrey H. Westrich, M.D. is Research Director of the Adult Reconstruction and Joint Replacement Service at HSS. Dr. Westrich has found himself being sought after for hip revisions, doing several per month on patients who fly in from all across the country.
He told OTW, “I’ve just published an article in Arthroplasty on how to approach recalled hip replacements. The original idea was to allow surgeons to intraoperatively do more customization of hip replacements. We traditionally put in a stem which includes a neck; the only modularity we had before that was with the head. The newer designs allowed a modular neck that allowed surgeons to put in a stem and then put in a neck (with a choice of many different lengths and angles). It also came in neutral, anteverted, or retroverted. This allowed us to place the stem in a way that accommodates the patient’s anatomy; it also allows us to intraoperatively select a neck that gave us the best chance of restoring leg length offset.”
“The greatest risk is that of dislocation, which can happen if you don’t restore offset. At HSS we had four surgeons doing this surgery with a dislocation rate of 1.2%. After modular neck prostheses initially came out, fractures of the metal neck (at the neck-stem junction) were reported.”
“Manufacturers switched to cobalt chromium, and although testing revealed no fractures, along came a new failure mechanism no one had ever seen—corrosion. This corrosion led to adverse local tissue reactions and elevated cobalt levels in the blood. The latter brings on systemic cobalt toxicity that causes problems like cardiomyopathy, renal problems, hair loss, rashes, etc. I’ve had patients showing up in my office with their teeth falling out because of this. Unfortunately, the manufacturers sold a lot of these implants before they realized it was a problem. My office constantly get calls from patients and even attorneys whose clients need to have the stem removed. This has greatly increased the amount of revision surgery that I am seeing on a monthly basis, not just for recall hip prostheses, but also for more revisions for other reasons as well.”
“To best care for patients with these recalled hips, surgeons should make sure that their patients return to the office for follow up. Many doctors will say, ‘Oh, I haven’t heard from the patient so everything must be alright.’ But this is an insidious process and not everyone has bad pain that brings them into the office, and if the problem lingers there could be major tissue damage that can result in a very poor outcome in spite of revision surgery. Also, you must always check the blood work to assess metal ion levels. Third, you should use a high resolution metal artifact reduction sequence (MARS), a special MRI for metal suppression to rule out an adverse local tissue reaction. This can show us in the earlier stages if the person has an adverse tissue reaction; at the end stage it will show any destruction of the abductor muscles.”
Read the full article on ryortho.com.