Wednesday, July 13, 2011

In Depth: Ankle Distraction Arthroplasty

Surgery four is a big one. The only thing I know about it: I want to have it in August. Depending on which treatment option I elect, future treatment options may no longer be available.

Time to research the crap out of these options.


Also referred to as arthrodiatasis, Greek for "to stretch out through a joint," distraction is a relatively new and experimental procedure to treat post-traumatic ankle arthritis. I hadn't heard of it until doing some research on Dr. Jeng last week.

This technique was first used on knee and hip joints in 1975. By pulling it apart, a low-pressure environment is created in the joint, allowing cartilage to repair itself. Studies have noted a "signi´Čücant reduction in pain along with improvement in function and radiographic appearance of the ankle...in most adults with post-traumatic arthritis undergoing ankle joint distraction."

Because the procedure is new, there isn't much data available on its success rate. The first article I read, "Five-Year Followup of Ankle Joint Distraction for Post-traumatic Chondrolysis in an Adolescent: A Case Report," discussed an outcome for a 15-year-old treated with this procedure around 2002.

The external fixator for this procedure is similar to the one I wore last year -- with one key exception: it's hinged, allowing you to bend your foot. The treatment also requires you to bear weight while wearing the external fixator for approximately 3 to 4 months. In fact, most surgeons will recommend weight bearing a day after surgery. This one-two punch has been shown to encourage cartilage growth while the joint is pulled apart.

The article indicates that the patient's joint was distracted to about 5mm by turning screws on the external-fixator 0.5mm a day. I found a video on YouTube showing how this is done.



As you pull the joint apart, it puts a great deal of pressure on the pins through your foot. I've read that as you distract, it's quite painful to walk. But after a transition period of pulling the joint apart, it becomes easier to walk.

This is a before and after x-ray of the patient's ankle. As you can see, before the treatment, the patient had no joint space. Six months later, you can see a significant amount of joint space has returned to the joint.

Another article, "Treatment of Ankle Arthritis with Distraction Arthroplasty," published in June 2010, recommends arthroscopic surgery to repair any bone spurs or other deformities before attaching the external fixator. To achieve dorsiflexion, the Achilles tendon can be lengthened and soft-tissue impinging motion can be removed.

This paper also surveyed existing literature on the subject, noting that there are more reviews on the topic than clinical studies. Here's a link to another preliminary review from 2009 discussing some early outcomes of the procedure. In general, results continue to improve for most patients after 1 to 2 years, but some had to have a fusion within the first year. Another paper indicated 16 out of 22 patients experienced clinical benefit for up to 7 years after the procedure.

Unfortunately, "patients with limited range of motion were not thought to be good candidates for distraction and were offered arthrodesis." My range of motion was good a few months ago -- around 10 to 11 degrees of dorsiflexion. I'm not sure where I'm at now. If I had no pain, I could probably get back to 10 degrees.

So let's get down to pros and cons:

Pros
  • It does not "burn bridges," meaning I can still opt for arthroplasty or arthrodesis
  • Snowboarding is an option
  • Reduced pain
Cons
  • Patience
  • Pin site infections
  • There's a 25% chance it may not work
  • The results may not last long

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