Total ankle revolution: Reduce pain, preserve function
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Affecting approximately 1% of adults worldwide, ankle arthritis is often found in patients with a history of ankle fractures and ligament injuries around the ankle joint.
While research has shown conservative treatments, such as weight management, medication and physical therapy, can alleviate symptoms and slow disease progression, these treatment modalities have limited benefits in advanced cases of ankle arthritis. In these cases, ankle fusion has historically been considered the gold standard of treatment. However, with improved materials, instrumentation and surgical techniques in the past few decades, total ankle arthroplasty has begun to supplant fusion as the go-to surgical treatment option.
Image: Amanda Rossback
“What we have noticed is that, traditionally, the gold standard to treat [patients with end-stage ankle arthritis] was ankle fusion,” Samuel B. Adams, MD, orthopedic surgeon at Duke Health, told Healio | Orthopedics Today. “But we found that, with ankle replacement, patients seem to be happier.”
Fusion shortcomings
Although ankle fusion provides pain relief to patients, Gregory C. Berlet, MD, FRCS(C), FAOA, orthopedic surgeon at the Orthopedic Foot and Ankle Center, said it has its downsides.
“One is it takes away motion, so you are going to give up function in order to get pain relief,” Berlet, the Section Editor, Foot and Ankle for Healio | Orthopedics Today, said.
Roy W. Sanders, MD, president and chief medical officer of the Florida Orthopaedic Institute, said adjacent joint stiffness is another drawback of ankle fusion.
“The problem with a fusion is that the subtalar joint and the talonavicular joint needs to do all the work, but that is not their primary function,” Sanders said. “Their primary function is eversion and inversion of the foot. For those two joints to start doing plantar flexion and dorsiflexion, over time, they will get arthritic, and then the only treatment for arthritis of those two joints is a fusion.”
Patients who undergo ankle fusion may also experience a slower recovery time, according to Carroll P. Jones, MD, section chief of the Foot and Ankle Institute at OrthoCarolina.
“Interestingly, for routine ankle replacement in my hands, recovery is quicker with a replacement than fusion,” Jones told Healio | Orthopedics Today. “You are not having to wait 6 weeks for the bones to fuse or grow together. And with replacement, you do not have a risk of nonunion because you are not doing a fusion.”
Benefits of total ankle
Alternatively, one of the main benefits of total ankle arthroplasty is the ability to preserve motion, according to Berlet.
“With joint replacement, the idea is that we are going to preserve your motion and, in some cases, improve your motion,” Berlet told Healio | Orthopedics Today. “I am going to be able to give you predictable pain relief, and I am going to be allowed to give you motion. That motion is important because you walk better, you feel better and you do not shift all of that stress to the adjacent joint, so subtalar joint arthritis after ankle replacement is much less common than it is after ankle fusion.”
Although there are subsets of patients contraindicated for total ankle replacement, including those with severe deformity, Sanders said patients with a cavovarus foot may benefit from the procedure.
“In people that have flat feet or cavovarus foot, you have to do fusions or at least a lot of soft tissue procedures to protect those joints if [the arthritis] is mild,” Sanders said. “But if it is severe, those patients often come in with not only a deformity, but additional instability in their ankle. Because of the deformity you are going to have to do fusions in their hindfoot. In those patients, now you can offer them a total ankle instead of ankle fusion. Avoiding pantalar fusion is a tremendous benefit.”
Failure of early implants
Despite positive outcomes associated with total ankle arthroplasty today, early total ankle arthroplasty implants were flawed, Sanders said.
“I was involved in the original DePuy Agility ankle [implant] in the ‘90s and 2000s, and the problem with that product was that the talus was a little too narrow and it was a complicated tibial component insertion where you had to fuse the tibia and fibula together in order to get the tibial component to be secure,” Sanders told Healio | Orthopedics Today. “Over time, they improved the talus so that it covered the entire surface of the talus, but by then the implant had fallen into disfavor.”
Sanders added that there were issues with the keel on the tibial side, which caused the medial malleolus to become osteopenic and cystic with time. The complicated instrumentation associated with the original Inbone prostheses (Wright Medical Group) also stalled the acceptance of other total ankle products early on, and there were no revision options when the ankle failed.
Fixation
One gamechanger for total ankle implants was the improvement of fixation of the implant to the bone, according to Berlet.
“In the early days of ankle replacement, we used to implant the implants, but they were not stable. If you want bone to grow into the implant, it has to be immediate, stable fixation. And we just did not get it,” Berlet said. “With modern materials and the availability of stems, we now leave the operating room knowing that it is solid, and any postoperative protocol is usually driven as much by the soft tissue envelope as it is by the implant itself because we know the implant is stable.”
Sanders said newer fixation methods have also improved the durability of implants and expanded the procedure's indications.
“Between the in-growth capabilities, the fact that they are semi-constrained, the talus is covered and the fibula is not part of the procedure, these products work well, and they work for a long time,” Sanders said. “And if they fail, now there are revision options.”
Patient-specific instrumentation
In addition, Kenneth J. Hunt, MD, associate professor and chief of foot and ankle surgery at the University of Colorado School of Medicine, said most companies that produce total ankle implants use “engineering specs from a CT scan that build in anatomy and alignment to make the process of placing the ankle replacement more predictable.”
“Incisions are smaller, operative time is less, the number of incisions is less and the accuracy is greater,” Hunt told Healio | Orthopedics Today.
This patient-specific instrumentation may also allow foot and ankle surgeons to have more foresight prior to an operation, according to Adams.
“We can almost do our surgery preoperatively with preop planning, and it helps make more accurate cuts and position the total ankle components more accurately,” Adams said. “Studies have shown that when the components are positioned correctly and the alignment is corrected, patients have a better outcome with their total ankle.”
Risks of total ankle
However, total ankle arthroplasty is not without its risks. According to Hunt, the polyethylene in a total ankle implant “will likely wear out in the patient’s lifetime.”
“It may not always be true for elderly patients, but for many patients who are in their 50s, 60s and 70s, they have to be prepared that that implant may wear out, that they may need a revision like a polyethylene exchange, which is similar to other joint replacements,” Hunt said.
Revision total ankle arthroplasty can be complicated if the patient’s bone has been resected, Jones said.
“If an ankle replacement goes bad, it is pretty devastating, whether it is an infection or early implant failure,” Jones said. “It is difficult to revise and get over that complication because often the implant might need to come out, might need to be fully redone and then you do not have as much bone to work with. It can be a challenging problem.”
He added, “There is an argument to use an implant that resects less bone so that when it fails, you have more to work with.”
Implant longevity
Questions also remain about the longevity of current total ankle implants, according to Hunt.
“The real answer is we do not know,” Hunt said. “The implant that I use has only been on the market for 11 years, and there have been upgrades to the materials in that implant.”
However, Berlet said new research slated to be published in 2024 will provide data showing the Inbone prosthesis has a 95% survival rate at an average of 11.7 years.
“We are finally at the point where we know if we put these in, they are going to last,” Berlet said. “We have always known that if you put ankle replacement next to ankle fusion, they do equally as well for pain relief, but ankle replacement does better for function. It has never been an argument that ankle fusion does better functionally. Nobody believes that, but the real holdback was always the longevity.”
He added, “Now that we are getting into these longevities, which 95% at 11.7 years is comparable to knee replacement, we can say we do not need to compromise function. We can give patients both function and pain relief and have confidence in the longevity.”
Trauma surgeons
Because ankle arthritis tends to be seen in patients who have previously experienced ankle trauma, Jones said these patients may be treated by trauma surgeons, which may lead to challenges.
“There are so many nuances that involve the foot. Not just an ankle replacement, but maybe the foot is crooked underneath the ankle. Then you need to do a lot of procedures to get the foot straight. That is something that trauma surgeons generally are not trained or comfortable doing,” Jones said. “If they are delving into a straightforward, simple ankle replacement, maybe it is feasible. When you start to get into nuances of deformity, that may be a bigger challenge.”
While some foot and ankle surgeons may believe trauma surgeons do not belong in the total ankle space, Berlet said total ankle techniques have evolved and are reproducible and teachable.
“Ankle arthroplasty can be done by foot and ankle surgeons, it can be done by traumatologists and it can be done by those who have experience in major joint arthroplasty,” Berlet said. “They will need to understand that ankle replacement is quite different than than knee and hip [replacements]. They will have to embrace the subtleties, but it is doable.”
However, trauma surgeons need to be interested in learning the nuances of the procedure, Sanders said.
“I do not know how to get [trauma surgeons] to have the interest, but most of them do not have a foot and ankle surgeon in their residency program that tackles a lot of this. This is an inherent problem,” Sanders said. “As total ankles become more common and consistent, then people will be more interested in it and residents will do and see a lot more and realize it is a procedure they need to learn.”
Tips, pearls
For trauma surgeons who are interested in performing total ankle arthroplasty, Sanders said they should learn how to perform soft tissue reconstructions around the hindfoot.
“It is not difficult for them to learn how to reposition a foot. They already do osteotomies of the calcaneus and do a whole host of other foot and ankle procedures, like ligament and tendon repairs individually,” he said. “But they need to feel comfortable putting it all together, so that when they see a patient with a bad pilon fracture or they see patients with a talus fracture with arthritis, they can then offer their patients alternatives to a fusion and feel comfortable in managing those associated deformities.”
Berlet said trauma surgeons should consider their incisions for total ankle arthroplasty and that “a fusion is not a great bailout for trauma.”
“The foot has been traumatized by an original trauma. If we traumatize it again with a fusion, it is a cumulative injury,” Berlet said. “I would do trauma surgery with the mindset that if they do develop posttraumatic arthritis, motion-sparing options are likely what is going to be best for the patient.”
If an ankle fusion is needed in a patient, Jones said keeping the lateral malleolus provides the opportunity to convert the fusion to an ankle replacement at a later time. He also said trauma surgeons should use hardware sparingly in trauma cases.
“We are seeing a lot of trauma cases where a tremendous amount of hardware is being put in, and if it is necessary, it is necessary,” Jones said. “But if these are younger patients that might be candidates for an ankle replacement down the road, all that metal has to come out and that can be quite difficult. So, potentially using less metal or resorbable implants might be advantageous for future reconstructive procedures.”
However, Hunt said it is also important to know when to refer a patient to a foot and ankle specialist who performs ankle replacements.
“Ankle replacements are unique. It is the only procedure that I do that I predict will wear out during the patient’s lifetime,” Hunt said. “It is technical. It has a high learning curve. It is not something you can dabble in. In short, any surgeon interested in doing ankle replacements should get foot and ankle training and do a lot of ankle replacements. It is not an easy thing to do once in a while.”
- References:
- Consul DW, et al. Foot Ankle Spec. 2022;doi:10.1177/1938640020980925.
- Gagne OJ, et al. Foot Ankle Int. 2022;doi:10.1177/10711007211060047.
- Goldberg AJ, et al. Health Technol Assess. 2023;doi:10.3310/PTYJ1146.
- Hermus JP, et al. Foot Ankle Surg. 2022;doi:10.1016/j.fas.2022.07.004.
- Li T, et al. J Orthop Surg (Hong Kong). 2024;doi:10.1177/10225536241244825.
- Wang Y, et al. Sci Rep. 2019;doi:10.1038/s41598-019-50091-6.
- For more information:
- Samuel B. Adams, MD, of Duke Health, can be reached at sarah.avery@duke.edu.
- Gregory C. Berlet, MD, FRCS(C), FAOA, of the Orthopedic Foot and Ankle Center, can be reached at gberlet@gmail.com.
- Kenneth J. Hunt, MD, of the University of Colorado School of Medicine, can be reached at jana.garin@cuanschutz.edu.
- Carroll P. Jones, MD, of OrthoCarolina, can be reached at carrolljones3@gmail.com.
- Roy W. Sanders, MD, of the Florida Orthopaedic Institute, can be reached at rsanders@floridaortho.com.
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