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Doctors hope newer versions of artificial ankles will better mimic nature’s joint


3 Star

Doctors hope newer versions of artificial ankles will better mimic nature’s joint

Our Review Summary

This news story attempts to explain the treatment options available for people who have severely disabling pain caused by osteoarthritis of the ankle. The article is generously sprinkled with both hope and caveats about the newest generation of ankle replacement implants intended to improve life for people like patient Dan Sivia: “Specialists hope… although it’s too soon to be sure.” “If the newer implants pan out…” “There is little research to tell how long newer versions will last…” Despite this attempt at even-handedness, however, readers are left with a fuzzy understanding of the potential harms of ankle replacements, little hard data about their potential benefits, virtually no understanding of the quality of the evidence on this topic, and no mention of a key source’s potential conflicts of interest.

  • Are there any randomized trials comparing 3rd-generation ankle replacement to nonsurgical treatments or fusion or any other treatments? If not, are there large cohort studies? Small case series? What are the limitations of the evidence?
  • What exactly do we know about the clinical outcomes of the new implants? What proportion of patients report less pain and improved mobility? How many fail? (See “Quantification of Benefits of Treatment” criterion.)
  • What are the short- and long-terms harms associated with ankle replacement? (See “Harms of Treatment” above.) This is not a simple procedure and complications are an important outcome.
  • What does it mean for an ankle replacement to fail, other than the need for “additional surgeries on your ankle in the future”? Can a failed implant usually be converted to an ankle fusion without problems? (There is some research to suggest that this is often the case.)
  • Given that the new generation of implants were approved in 2005, does that mean there are no published data on their durability beyond a year or two?
  • Is there any precedent in the development of other weight-bearing joint replacements (hip, knee) to suggest that outcomes improve after an implant is re-engineered to “work more like the joint you’re born with?” Is there good research to buttress the contention that the new ankle implants “really mimic a natural ankle”?
  • Is there no expert free of industry conflicts who could provide more than a few words of independent assessment of the newest ankle implants? The absence of such a source is troubling in a story about a medical device with a long history of problems. (See “Sources of Information” criterion.)

 The story provides good reasons to be cautious. So, in the end, why wasn’t it?


Does the story adequately discuss the costs of the intervention?


The article says that the costs of a typical ankle replacement can “reach $50,000.” However, it doesn’t mention the cost of the most common alternative, fusion, or take into account the future cost of treatment after the device fails.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story provides no quantitative estimate of benefit from ankle replacement or ankle fusion—-no information about what patients would consider "real" outcomes.  One meta-analysis has reported that 38% of patients treated with ankle replacement had an excellent result, 30.5% had a good result, 5.5% had a fair result, and 24% had a poor result. Among people who had fusion, the corresponding numbers were 31%, 37%, 13%, and 13%. (J Bone Joint Surg Am. 2007;889(9):1899-905.) Even reporting the research on earlier generations of ankle replacement would be helpful, since it would reinforce the message that people should approach the new treatment with caution. It would be fairer if the writer simply stated that these are patients who have a real problem, but one that currently lacks a good, proven treatment option.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

The article explains some of the potential harms and limitations of an ankle fusion, but says little about those of ankle replacement. What are the short- and long-term risks? (In the closing paragraph there is a vague reference to “different risks of wound infections” with different implants.) What does it mean when an ankle replacement “fails”? Is fusion usually still an option? This is not a simple procedure and complications are an important outcome.

For example, an analysis of more than 5000 patients in California found that people who received an ankle replacement had an increased risk of device-related infection and were more likely to require a major reoperation than people who had an ankle fusion. The rates of major reoperations after ankle replacement were 9% at one year and 23% at five years compared with 5% and 11% following ankle fusion. (J Bone Joint Surg Am. 2007;89(10):2143-9.)

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The news story summarizes the literature on ankle replacement in a single sentence. The article says that a review in the Journal of the American Academy of Orthopaedic Surgeons (JAAOS) “cautions that so far, there is little research to tell how long newer versions will last—and that few hospitals have much practice in implanting them.” In doing so, the story cites one review article, no original research, and makes no attempt to characterize the quality of the clinical evidence to support the review’s conclusions.

Although it issues a number of caveats, the story fails to simply state that there are no large, long-term studies examining these devices. Part of the problem is the "FDA approval". To the lay person, this may imply efficacy even though it often requires only a minimum amount of short-term evidence.

Does the story commit disease-mongering?


The article says some 200,000 people seek care for their ankles annually. A reader could come away with the mistaken impression that there is an alarmingly high prevalence of ankle pain that is disabling enough to warrant an ankle replacement. The actual prevalence is unknown, but is likely to be a small proportion of that number, though more than the 10,000 or so annually who are currently getting fusions and ankle replacements. 

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

The story fails on a critical point: It neglects to mention key potential conflicts of interest in its main expert source. The story includes interviews with one patient who had a successful ankle replacement and one surgeon (Dr. Haddad) who is currently developing an ankle replacement implant for Wright Medical Technology and is also the lead investigator in a trial sponsored by device maker DePuy Orthopaedics of a DePuy ankle implant, according to Haddad’s website. The story briefly cites a second orthopaedic surgeon (Dr. Wapner), who is said to believe that the newest implant designs will last longer than previous designs.

Does the story compare the new approach with existing alternatives?


The story describes some of the pros and cons of ankle fusion, the main alternative to ankle replacement. It makes no mention of other surgical or nonsurgical treatments. According to the story, fusion appears to be a more predictable operation than ankle replacement, but also one that triggers unwelcome long-term problems.

Does the story establish the availability of the treatment/test/product/procedure?


The story explains that ankle replacements have gone out of favor and that device makers are attempting a comeback with a “third-generation” model. It also explains that the FDA began approving the current generation of implants in 2005, but few hospitals have experience with the procedure.

Does the story establish the true novelty of the approach?


The story explains that ankle replacement has been around for decades, but that a new generation of implants was recently approved in 2005.

Does the story appear to rely solely or largely on a news release?


The story uses several sources and does not appear to rely solely or largely on a news release.

Total Score: 6 of 10 Satisfactory


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