Total ankle arthroplasty shows promising results, but obstacles exist

Although total ankle arthroplasty has gained greater acceptance as a viable ankle treatment option, some challenges with the procedure remain. For example, modern implant designs continue to be associated with some complication risks and clinical success often depends greatly on surgeon experience and the implantation technique used.

“Total ankle replacement has gained more popularity in the last years, and there are an increasing number of orthopedic surgeons doing them,” Beat Hintermann, MD, chairman of the Orthopaedic Clinic, Kantonsspital, in Liestal, Switzerland, said. “However, as a majority of osteoarthritic ankles are of a post-traumatic or deformity origin, doing a successful total ankle replacement requires a broad armamentarium of techniques to address these complex pathologies.”

Timothy R. Daniels, MD, FRCSC, of the University of Toronto, said rebuilding the ankle — a construct that must function for a long period — depends greatly on the skill set of the surgeon. Daniels noted that most patients who require total ankle arthroplasty (TAA) have had previous deformities or traumatic conditions. The intricacies of ankle anatomy, ankle deformities and the precision required to balance the ankle demand surgeon experience.

“You need to be an expert in the management of all deformities surrounding the lower extremity and the foot and ankle in order to be a competent ankle arthroplasty surgeon,” Daniels told Orthopedics Today. “People who do not do this operation often have a higher failure and complication rate.”

Steven Douglas K. Ross, MD, of the University of California, Irvine, stressed that surgeons must correct all deformities before performing the TAA to ensure a good plantigrade position. It is not uncommon for him to perform tibial or fibular osteotomies, calcaneal osteotomies, midfoot or hindfoot fusions around the ankle joint replacement and tendon transfers all in the same operation to balance the foot.

“The arthroplasties do poorly if deformities are not able to be corrected, so all the forces have to be corrected,” Ross told Orthopedics Today. “It does take quite a bit of effort to master the skills in terms of [correcting] the deformities that exist and having the implant end up in a nice plantigrade position.”

Hintermann, Daniels, Ross and Roy Sanders, MD, of Florida Orthopedic Institute, said surgeons require extensive experience to learn the technical skills to perform TAAs. In soft tissue procedures, such as a posterior capsular release, a surgeon could easily cut the nerve or posterior tibial tendon with the saw, Sanders said.

“You need to do fellowship or at least spend time with somebody who does total ankles so you can see their patients, the complications [and] understand what it is you need to do,” Sanders told Orthopedics Today.

Hintermann recommends surgeons perform about 20 procedures with an experienced surgeon before attempting the operation alone.

Implant designs

According to Daniels, cemented first-generation implant designs universally failed, but newer, uncemented prostheses provided a more anatomic ankle with improved functional outcomes and greater longevity. Researchers of published studies have found no significant differences for longevity or function across different brands of implants, he said. The Swedish, Norwegian and New Zealand TAA registers – three of four such registers worldwide – reported average TAA failure rates of 10% in 2007.

In a 2007 study, Hosman and colleagues examined a cohort of 202 ankles in the New Zealand National Joint Register and found a 7% failure rate across four models of TAA implants. The designs studied were the Agility prosthesis (DePuy, a Johnson & Johnson company; Warsaw, Ind.), the Scandinavian Total Ankle Replacement or STAR (Waldemar Link; Hamburg, Germany), the Mobility implant (DePuy International; Leeds, United Kingdom) and the Ramses prosthesis (FH Orthopedics; Chicago).

Overall ankle replacement survival was 89% at 5 years and 76% at 10 years in a study Fevang and colleagues conducted of 250 ankles in the Norwegian Arthroplasty Register in 2007. The overall failure rate was 11%. Their analysis included the STAR prosthesis and the Thompson Parkridge Richards or TPR implant (Smith & Nephew; Memphis). Head-to-head survivorship results were the similar for both designs.

Henricson and colleagues studied 531 prostheses in the Swedish Ankle Arthroplasty Register, including the STAR prosthesis, the Buechel-Pappas implant (Endotec, Inc., Orlando, Fla.), the Ankle Evolutive System or AES design (Transystème, Nimes, France), the Hintegra prosthesis (Integra LifeSciences, Plainsboro, N.J.) and DePuy’s Mobility device. The investigators reported 78% overall survival at 5 years and 62% survivorship after 10 years.

Indications

Sources interviewed agreed that the main indication for TAA is symptomatic end-stage ankle arthritis, with or without deformity. However, Hintermann said that patients with systemic types of arthritis, such as rheumatoid arthritis, may also require TAA. Patients with post-traumatic fractures or deformity may also be candidates for the procedure.

“In our country, about 80% of post-traumatic cases occur after fracture or trauma,” he said.

Many patients with end-stage ankle arthritis are young and the decision to perform TAA is challenging because the implant could fail in 10 years to 15 years, Daniels said.

“When I am consulting with patients with regards to whether they should have a fusion or replacement, I am telling them all the factors. My bias is to consider an ankle fusion in a younger patient population, but do it in a way that it could be converted to an ankle replacement down the line should they begin to develop painful ipsilateral hindfoot arthritis or should they begin to get frustrated with the stiffness of their foot,” Daniels said.

Patients with neuropathic diseases, such as diabetes, nerve injuries or neuromuscular injuries, are not indicated for TAA, Daniels said. Other contraindications include inadequate bone stock diagnoses, such as avascular necrosis of the talus or tibia, severe deformities or a history of infection.

The decision for patients to undergo TAA should be individualized based on the patient’s functionality, gender and comorbidities, according to Hintermann, Daniels, Ross, Sanders and Dan-Henrik Boack, MD, of the Foot and Ankle Center, Berlin, Germany.

“[Patients] have to be physiologically active enough to justify the intervention and not have significant comorbidities that make it unreasonable,” Ross said.

At his institution, Hintermann has seen a higher TAA failure or revision rate in men than in women. Therefore, he and Sanders are more likely to recommend women for the procedure.

Upper and lower age limits

There are no published studies supporting the use of age as an indication for TAA. “When it comes down to an age limit, it is more of a longevity issue in terms of how long that individual is going to be functionally using the reconstructive procedure you performed,” Daniels said. “Current data suggests 10-year survivorship is 75% or 90% depending on which article you read, and if the patient is 65, there is a better chance that implant is going to last their lifetime as opposed to if they are 45.”

Daniels said young patients may be indicated for TAA if they are not physically active, but most are recommended to undergo fusion.

“The more physically demanding and the younger the patient is, the more likely they are going to be advised to undergo fusion,” he said. “The older they are, the less physical demands on their lifestyle they are, the more likely there will be more people recommending a total ankle arthroplasty.”

According to Boack, regardless of age, patients who require a more mobile ankle may be ideally suited for TAA, although he advised against TAA in children. Ross warns patients must be physiologically active enough to justify the intervention because the plastic and metal implant will eventually wear out and require a revision.

“Plastic wears and [the implant] can become loose and require revision,” Ross said. “When they do require revision, of course you are losing more bone.”

Arthroplasty vs fusion

Before TAA prostheses and surgical techniques became more commonplace, fusion was the only option for patients. Of note, no published studies currently recommend fusion over TAA. A recently presented study by Daniels and colleagues using the Canadian Orthopaedic Foot and Ankle Society ankle reconstruction database found equivalent function between TAA and fusion in patients with end-stage arthritis.

Today, fusion may still be better suited for individuals with poor range of motion, previous trauma or pain due to soft tissue changes, according to Boack.

“Some of the soft tissue changes could also lead to pain, and if you try to bring motion into the joint, it could lead to more soft tissue pain,” Boack said.

Fusion provides stability, but the stiffness causes increased stress to the surrounding joints, which may lead to deterioration and ipsilateral peritalar arthritis, according to Daniels.

Common complications

Surgeons who spoke with Orthopedics Today noted mechanical loosening following insufficient implant/bone fixation, osteolysis, low grade infection, deep vein thrombosis, instability of the artificial joint, asymmetrical polyethylene meniscus wear, bony impingement, malleolar fracture and cystic deformity as potential complications of TAA.

Little is known about the revision of TAA beyond 15 years. In a study beginning in 1990, Boack and colleagues found four loosenings among 750 TAAs. Bony cysts and polyethylene wear led to 1.8% of those patients requiring revision.

National registries in Europe, New Zealand and Australia have reported revision rates higher than studies published by the implant designers, according to Daniels, which may point to bias reporting and/or reflect the degree of expertise that is required to make ankle joint arthroplasty a successful procedure.

“Maybe in 5 [years] to 10 years, we can say more and we can give more accurate indication of the survivorship of the current ankle arthroplasties,” he said.

Patient restrictions and the future

After TAA, Ross asks patients to limit running and jumping activities.

“The forces are more concentrated in ankles because the surface areas are smaller than the knee, so you have to be willing to limit your activity to daily, community-type activities, but no running and jumping,” Ross said.

Hintermann advises against contact or high-impact sports. However, Hintermann and Daniels allow downhill skiing, walking, bicycling and non-competitive tennis. Boack said it is most important for patients not to overload the ankle, and he allows walking, climbing and water sports.

In the future, implant designs are expected to become more physiological, according to Hintermann and Daniels. The understanding of balancing the unstable or deformed hindfoot has improved in the last 10 years to 15 years, leading the “foot and ankle community” to a better understanding of hindfoot biomechanics.

“There are too many ankle [designs] on the market; just copies, or mostly copies,” Hintermann said. “We know from history that some designs do not work. There are some concepts that allow for too much of the motion on non-physiological planes, such as the front plane.” – by Renee Blisard Buddle

Should there be an upper or lower age limit where you recommend not doing total ankle arthroplasty?

No established age limits

There are no established upper or lower age limits for total ankle replacement (TAR). However, there are limited long-term data on the effectiveness of TAR and available data suggest that TAR has a relatively short lifespan. It is for this reason that some suggest that TAR not be recommended for people younger than 50 years. However, one must not mistake the ideal candidate who is older than 50 years , not too heavy and is not extremely active, as the only candidate. In fact, there is no published age limit for TAR. There is an expectation that the patient not participate in strenuous activity after the procedure. A younger patient might be more apt to engage in this type of activity. Furthermore, the younger patient may simply outlive the TAR. Other predictors of a poor outcome include diabetes, neuropathy and poor circulation, which are more likely to exist in an older population. All this must be weighed against the fact that ankle fusions develop problems over time as well. Each patient must be evaluated individually by diagnosis, activity level, reasonable expectation and neuromuscular ability. Age has nothing to do with it.

Carol C. Frey, MD, is Section Editor, Foot and Ankle for Orthopedics Today and Director of Orthopedic Foot and Ankle Surgery at West Coast Center for Orthopedic Surgery in Manhattan Beach, Calif.
Disclosure: Frey has no relevant financial disclosures.

No strict limitations

Total ankle replacement (TAR) has evolved into a reliable treatment option for patients with end-stage ankle arthritis and a valuable alternative to ankle arthrodesis. Aside from skeletal maturity, I do not feel that there are any strict limitations on age for TAR. Rather, I think other factors including choice of implant, physical condition, activity level and lifestyle are more important in the decision to perform ankle replacement. In fact, no age limits have been formally established and there is little scientific literature to help guide the surgeon. The average age for TAR is not much different than hip or knee replacement, probably around 60 years of age. In general, it is best to delay surgery as long as possible because of concerns for implant longevity. However, in certain etiologies, such as rheumatoid arthritis or hemophilia, progression to end-stage ankle arthritis occurs much earlier in life. With diminished quality of life, patients in their 30s and 40s can certainly be candidates for ankle replacement if they understand the risks of the procedure and the potential for multiple revision surgeries.

On the other end of the age spectrum, medical comorbidities of patients in their 70s, 80s and 90s should be more of a concern than age itself in precluding ankle replacement. In many instances, this patient population is more suitable for TAR (over arthrodesis) as postoperative immobilization and progression to weight bearing times are generally shorter, providing for less muscle atrophy and earlier return to function. Likewise, ankle replacement may result in less gait alteration and functional impairment. Additionally, elderly patients are generally low demand with regard to activity thereby decreasing the risk of prosthetic revision. In summary, a successful TAR relies on many factors and regardless of age can be a successful alternative to arthrodesis.

Samuel B. Adams, MD, is the assistant professor and director of Foot and Ankle Research in the Department of Orthopedic Surgery at Duke University Medical Center in Durham, N.C.
Disclosure: Adams has paid consultant relationships with Extremity Medical and Integra.

No upper limits

We are a little bit biased. We are comfortable with not only the primary total ankle replacements, but doing revisions and dealing with many of the complications associated with ankle replacements. So our age limits tend to be probably outside the norm. But we will, in the right patient, go down to the age mid to low 20s. I think as long as patients are medically healthy and stable, I do not think there is necessarily an upper age limit for an ankle replacement.

Selene G. Parekh, MD, MBA, is Associate Professor in the Department of Orthopedic Surgery at Duke University, Durham, NC.