Perceived by patients to cause the same extent of impairment as congestive heart failure and end-stage kidney disease, ankle arthritis affects about 1% of the United States population and mostly occurs from post-traumatic ankle injuries.
Although ankle fusion has historically been the gold standard treatment for ankle arthritis, sources who spoke with Healio/Orthopedics Today said the use of total ankle replacement (TAR) for this indication has increased in the past decade.
“Total ankle replacement is definitely growing, and it has particularly grown over the last 15 years as we have had new and better implants,” Scott J. Ellis, MD, professor of orthopedic surgery at Hospital for Special Surgery and Weill Cornell Medical College, told Healio/Orthopedics Today.
According to Lew C. Schon, MD, FACS, FAAOS, director of orthopedic innovation in the Institute of Foot and Ankle Reconstruction at Mercy Medical Center, the main benefit of ankle fusion is that it can provide patients with good pain relief, stability and a decent gait, and can lead to a comfortable and functional life. Although patients with an ankle fusion can sometimes walk 10,000 to 15,000 steps per day, Schon said many of his patients with fused ankles can only walk up to 5,000 steps per day.
“There is a range of activities they can do, but certain things that they cannot do,” Schon said. “For example, going up and down hills, operating foot pedals, sliding on boots, getting up from a squatted position and kneeling can be difficult for them.”
While ankle fusion and TAR provide equal pain relief for patients, James K. DeOrio, MD, professor of orthopedic surgery and director of the foot and ankle fellowship at Duke University, said patients experience more comfort from a functional standpoint after TAR. He uses the Vantage ankle replacement (Exactech), which he helped design.
“From a functional standpoint, [ankle replacement] is more comfortable to be able to move around your apartment, your house, go for walks or go for a 5-mile hike,” DeOrio told Healio/Orthopedics Today. “Without that movement, it is awkward," he said.
Compared with ankle fusion, Schon said his patients who undergo TAR can anticipate achieving 5,000 to 15,000 steps a day.
“We have not had trouble with people operating any pedals, foot controls. Squatting is easier, kneeling is easier, patients can go up and down hills better, their cadence is more normal, their symmetry between the legs is usually more normal than with the fusion and we have not seen any hindfoot or midfoot arthritis significantly advance,” Schon, who utilizes the Trabecular Metal Total Ankle (Zimmer Biomet) implant, said.
David I. Pedowitz, MD, MS, chief of the division of foot and ankle surgery and associate professor of orthopedic surgery at the Sidney Kimmel Medical College, Thomas Jefferson University, Rothman Orthopaedic Institute, said patients who undergo TAR may have a quicker recovery compared with ankle fusion and more patients report feeling that their ankle is more normal after a replacement.
“It also allows them to keep the motion that they have in their ankle,” Pedowitz, who is an Orthopedics Today Editorial Board Member, said. “Some people are under the false assumption that an ankle replacement will give them motion, but an ankle replacement does not give anyone motion. It hopefully allows you to keep the motion you already have.”
Another similarity between ankle fusion and ankle replacement is the procedures both come with the risk of needing additional surgery, according to sources.
Ankle fusion places stress on the subtalar joint which can lead to arthritis and the need for subtalar arthrodesis, according to DeOrio.
“If you fuse an ankle joint, patients can get along well, but when you get arthritis in the subtalar joint, then the only treatment for that is to do a subtalar arthrodesis,” he said. “That locks down even more motion, and it feels more like a peg leg than it does a real ankle.”
While the joints around the ankle do not experience as much stress with an ankle replacement as they do with a fusion, patients who undergo TAR may need to undergo a revision, depending on patient and anatomic factors, according to Pedowitz.
“Essentially, most patients under the age of 70 [years] will require a revision at some time in their lives just because ankle replacements are expected to last 10 to 15 years with, of course, exceptions,” Pedowitz, who utilizes the Cadence Total Ankle System (Smith & Nephew), said.
Ellis said a second procedure may also be needed among patients with a TAR if they develop cysts in the bone or experience loosening or an infection.
“If the implant becomes loose or it becomes infected, then you have to take it out and revise it and we know that the results of revision are never as good as the primary total ankle,” Ellis said. “You could also convert the total ankle replacement to a fusion, but the problem is then you take out the implant and there is a hole there, essentially, because of the bone that you have taken out plus the implant, and so it is not easy to get an ankle to fuse at that point.”
If a patient with a TAR presents with a loose tibia, sources who spoke with Healio/Orthopedics Today agreed they would prefer to perform a revision over a fusion.
W. Hodges Davis, MD, who said a big part of his practice consists of performing revision TAR, said he has not fused a failed replacement in 7 years.
“A fusion with big bone defects has a high complication rate and a high nonunion rate, and I feel like I have a lower complication rate with the revision than with doing the fusions,” Davis, of the OrthoCarolina Foot and Ankle Institute and Atrium Health, told Healio/Orthopedics Today.
When a revision procedure cannot be performed in a patient with a loose tibia, Schon said another option is a tibiotalo or tibiotalocalcaneal fusion. However, these fusions may have trouble healing, he said.
“It could be the patient is a poor host, meaning that they are unhealthy or that they have some local tissues that are not optimal for healing,” Schon said. “Then, we have found that the large void that remains after removing the implant requires a bone graft, either from a bone bank or the patient’s own body. Unfortunately, many surgeons encounter trouble at the junctions getting complete healing. So, maybe around 30% of the patients have a significant problem with a replacement take-down converted to a fusion.”
When performing TAR, sources who spoke with Healio/Orthopedics Today said most of the time they also have to perform an ancillary procedure, depending on associated injuries.
“Many of these patients have prior hardware, so if I am taking down a fusion, I have to remove the fusion hardware,” Schon told Healio/Orthopedics Today. “Similarly, if I have a previous ankle fracture, those plates and screws must be extracted.”
Schon, who is also a professor of orthopedics at NYU Langone Grossman School of Medicine and Johns Hopkins University, said he often must repair ligaments and tendons that are responsible for ankle instability, deformity or chronic weakness.
DeOrio said he performs as many as six or seven ancillary procedures occasionally at the time of TAR, including a calcaneal osteotomy, a dorsiflexion osteotomy of the first metatarsal, a midfoot fusion, a complete medial deltoid release and a medial malleolar or tibial osteotomy.
Another common ancillary procedure done at the time of a TAR is a gastrocnemius or Achilles recession, according to Pedowitz.
“A common complaint of patients with ankle arthritis is not only that it hurts, but that it is stiff, and when you put a new ankle in using an ankle replacement it does not necessarily give you more motion. But if one of the obstacles to motion is a tightness of the calf muscle, you can sometimes lengthen the calf muscle alone or the Achilles tendon itself to get a little more motion,” he said.
Currently, there is no research on which patients may do best and be most satisfied with ankle replacement vs. ankle fusion, according to Pedowitz.
“I want to resist the temptation to say that one procedure is better over the other based on how it looks on an X-ray or how many years afterward patients need a second surgery because that is using my metrics to say it was worthwhile and successful when, really, I am not the one living with that ankle,” Pedowitz told Healio/Orthopedics Today. “In a young patient who we know in advance will require a second surgery because the ankle replacement will not last, if we allow that patient to have an ankle replacement and 10 or 15 years later they need another one, some surgeons might think of that as an unsuccessful paradigm for surgery. However, that patient may have been given an ankle and a life with that ankle that they were happy with and happy with the decision they made.”
More research with long-term data may tip the scales in favor of ankle replacement or ankle fusion, according to Davis. With the current data that are available, Davis, who utilizes the InBone Total Ankle System (Wright Medical), the Infinity Total Ankle System (Wright Medical) and the Invision Total Ankle System (Wright Medical), said his research has shown that most failures occur within the first 2 years of a TAR and that patients who do not experience a failure within the first 2 years can expect to have implant retention at 10 years.
“Occasionally, in the first 10 years, in particular in 8 or 9 years, a small percentage, maybe 10%, will have to have a tune up operation where they will develop some bone spurs. We call that gutter impingement, or they will start getting some stiffness because they are developing bone in places we do not want it” or heterotopic ossification, Davis said. “We occasionally have to do a second operation, but rarely do we have to replace the implant.”
Although Pedowitz quotes to his patients a survival rate of 70% to 90% at 10 years for ankle replacement, surgeons should be cautious when reviewing data on ankle replacements because much of the data do not reflect the same type of ankle replacement on the market today or even one specific model of ankle replacement prosthesis, he said.
“The data that say your ankle replacement will last for 15 years, that replacement is probably not even on the market anymore in its same form. So, you have to interpret those data as best as you can,” Pedowitz said. “The other thing is there are no data that are specific for one implant over another. So, the 70% to 95% survival rate at 10 years is just ankle replacement in general, not any one company’s ankle replacement.”
In addition to long-term data, Davis said revision data are also needed on ankle replacement.
“Can you replace a replacement if it fails?” Davis said. “That is a question a lot of my patients ask me and, because I do so many revisions, it is an easy one for me to answer. But something that we need more data on is: How do we do with revisions and, also, what is the function of those patients?”
Research is also needed on how to diagnose infection in a patient with a TAR, which Pedowitz said is a complex issue with regard to all total joint replacement procedures.
“Since ankle replacement is done at only a fracture of the volume of hip and knee replacements, it is hard to get a massive amount of data to review and on which to draw conclusions,” Pedowitz said.
Davis said more data are also needed on how to balance the foot and fix foot and ankle deformities during a replacement procedure, while Ellis said a greater understanding is needed on why a patient may continue to have pain after an ankle replacement.
One important item to research is whether there is an ideal position of the TAR implant that makes it function better, Ellis said.
“There are so many degrees in components to how you put them in, meaning if it is in varus or valgus, how it is turned, how it is rotated, how high or low you put the implant. I just think there are so many variables of how we put the replacement in that we need to understand how those influence outcomes,” he said.
As more research comes out on TAR, Pedowitz said he believes the procedure will ultimately be used more frequently than ankle fusion.
“I see [total ankle replacement] being done through smaller incisions and gaining greater popularity, not only with surgeons but with patients, over ankle fusion,” Pedowitz said.
Schon said the new generation of implants will improve TAR outcomes by taking away less bone and using better materials (metal and plastic) and more sophisticated alignment systems. The mechanics of the available implants will be better assessed with longer term follow-up. Ultimately, the modifications will provide for a more reproducible procedure with superior results, he said.
“It’s important to know, however, that there is no point in doing something easier if you do not have a better, durable implantation,” Schon said.
Reference: Hermus JPS, et al. Foot Ankle Surg. 2021;doi:10.1016/j.fas.2021.12.001.
Even with more data and improved techniques and implants, TAR will not become well-known without orthopedic surgeons, primary care physicians and nonoperative physicians being educated on the procedure and knowing that it is an option for their patients with ankle arthritis, according to Davis.
“[Total joint replacement] is a life changer and if you have a chance to change someone’s life like that, it validates so much of what we are about,” Davis said. “So, just getting the word out about it is something that I think will also be a tipping point.”
DeOrio said patients with TAR are great to care for because they are so appreciative of how the surgery preserved motion and relieved their pain.
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