Taking a Step Back to Look at Ankle Joint Replacements

In this review and update, orthopedic surgeons at Duke University Medical Center take a look at the results of ankle joint replacement called total ankle arthroplasty or TAA. They present a thorough examination of all aspects of TAA from studies published and evidence gained so far on this topic.

Total ankle arthroplasties have been around long enough now to be in what is referred to as second-generation implants. Second-generation means the original design has been improved and changed in a significant way. Along with improved implants come better surgical techniques and surgical tools.

But are the results matched in terms of implant performance and survival? What about patient satisfaction, which is usually based on reduced pain levels and restoration of ankle joint motion and function?

In other words, what's the evidence to support this treatment for end-stage ankle arthritis? And are there real advantages to ankle replacement over the current standard procedure of ankle arthrodesis (fusion)? Should the various types of ankle arthritis (inflammatory, post-traumatic, osteoarthritis) be treated differently?

There are many individual (small) studies on total ankle arthroplasty (TAA). Surgeons explore the results of their own techniques or results of a specific implant. There are a couple meta-analyses (multiple small studies combined together for greater statistical significance). But an analysis of most of the studies reveals problems with study design and research standards.

Based on their review of current published analyses of total ankle arthroplasties, the authors of this report give a C grade of recommendation for the treatment of end-stage ankle arthritis with TAA. A C grade means the evidence is of poor quality and conflicting. Does this poor grade mean no one should get an ankle joint replacement?

No -- a closer look at the details of various studies still gives some good information. But the need for better study designs and comparisons is pretty clear. Here are a few of the observations the authors made as they summarized study findings.

  • Implants last up to 12 years so far in 95 per cent of the patients. Younger age (less than 50 years old) and higher activity level may be linked with risk of implant failure.
  • As with other types of joint replacements, loosening and subsidence (sinking down into the bone) are the two most common problems.
  • There isn't one brand of implant that has tested superior to all others.
  • Patients often still experience some ankle pain after an ankle joint replacement. The reason(s) for this remain unclear.
  • Technical errors are more common as the surgeon is first learning to perform this surgical procedure. Complication and revision (second surgery) rates are higher and implant survivorship is lower for patients when the surgeon is new to this procedure.
  • Active adults can expect to return to light recreational sports and activities. Hiking, biking, and swimming seem the most popular activities. High impact or strenuous activities are not advised.
  • It is possible to convert a fused ankle to a moveable ankle with an ankle prosthesis. Patients must be selected very carefully for this procedure. Guidelines for patient selection for this conversion have not been published.

    As surgeons become more familiar with ankle arthroplasty procedures, the criteria for who qualifies to receive these implants will continue to expand. Survivorship of implants can be extended by minor surgeries to improve alignment, relieve impingement if anything is being compressed, and/or replace the plastic liner that is part of the implant when it wears out.

    Future research that uses standardized patient outcomes will make it easier to compare results of total ankle arthroplasty (TAA) with ankle arthrodesis (fusion). Likewise with consistent reporting of results, it will be possible to compare one type of TAA to others.

    The goal will be to find out which one works best for different patient problems (inflammatory arthritis versus post-traumatic arthritis or degenerative osteoarthritis). And finally, long-term studies (10, 15, 20-year follow-up) are really needed to see what happens over time for these patients. This type of information will help surgeons advise and guide patients through the decision about what type of treatment is best.

  • Reference: 

    Mark E. Easley, MD, et al. Results of Total Ankle Arthroplasty. In The Journal of Bone and Joint Surgery. August 2011. Vol. 93-A. No. 15. Pp. 1455-1468.

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