Are Ankle Implants On The Comeback Trail?
Older ankle implants, initially used in the late ‘70s and early ‘80s, were failures. They either popped out, wore out or subsided into the bone. One podiatric surgeon recalls removing at least one failed ankle implant a week during his residency. Lately, however, there has been a resurgence of interest in ankle implants, although a palpable amount of trepidation and skepticism remains.
While only a handful of podiatric surgeons in the United States have used the newer implants (the Agility Ankle and the Beuchel-Pappas device), the majority believe they are more biocompatible. They are reportedly more durable and less-constraining, which should decrease the risk of component loosening and allow for greater motion.
Striving for increased motion is one reason why surgeons might consider the implant ankle arthroplasty over the arthrodesis procedure for treating chronic ankle pain. While experts say arthrodesis success rates are certainly higher (in the 80 to 90 percent range) now than they were a couple of decades ago (in the 50 percent range), this procedure is reportedly more limiting in terms of motion and may lead to subsequent degeneration in proximal and distal joints.
While both procedures offer pain relief and improved stability, there are other key considerations to keep in mind.
• Ensure proper patient selection. The majority of opinion on implant ankle arthroplasty is that it’s indicated for older patients (some say greater than 50 years of age while others say 60) who have rheumatoid arthritis or osteoarthritis caused by trauma or ligamentous injuries. More specifically, surgeons tend to reserve this procedure for patients who are more sedentary and have sufficient ankle stability to withstand the implant.
If the patients are extremely active, obese or have a history of severe osteoporosis, Charcot neuroarthropathy or neuromuscular disease, surgeons say you should opt for the ankle joint arthrodesis.
• Consider the degree of difficulty and potential complications. All the surgeons agree that there is a significant learning curve with the implant ankle arthroplasty. One well-respected DPM notes that performing a syndesmotic fusion, a technically difficult procedure for even the most experienced surgeons, is “critical” to the success of the Agility implant. Even an enthusiast of the ankle implant procedure says the learning curve is steeper “ … than anything else we’ve seen in podiatric surgery.”
Experienced podiatric surgeons also cite the procedure’s potential for serious complications, ranging from mallelor fractures and nerve damage to subsidence and deep infection, just to name a few.
• A need for more follow-up studies. A 1998 study from The Journal Of Bone and Joint Surgery assessed long-term results of the Agility implant and found that 79 percent of patients were extremely satisfied with their implants. One DPM, who has used the Beuchel-Pappas implant overseas and in investigational U.S. trials, reports that a study of over 1,500 Beuchel-Pappas implant procedures in Europe found that 80 to 85 percent of patients had “good to excellent” long-term results. Still, the paucity of other research showing long-term outcomes with ankle implants is a sticking point that shouldn’t be overlooked.
Upcoming articles in the journal literature may shed further light on this issue. As this issue went to press, the FDA was still collecting data from the investigational trials of the Beuchel-Pappas implant and a few more podiatric surgeons will reportedly be able to start using the Agility implant later this year.
However, unless future developments reveal otherwise, it is clear the arthrodesis remains the surgical gold standard for end-stage rheumatoid or arthritic disease of the ankle.