Complications, surgeon experience limit greater adoption of total ankle arthroplasty

Total ankle arthroplasty has greatly improved in effectiveness to the point where it has gained greater acceptance in Europe as a viable ankle treatment option by orthopaedic surgeons and their patients. Some challenges with the procedure remain, however. For example, modern implant designs continue to be associated with some complication risks. Each country also varies in how surgeons perform the procedures and, as a result, 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 orthopaedic 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. Therefore, the overall amount of specialized centers for total ankle replacement may be limited.”

The popularity of total ankle arthroplasty (TAA) has varied by countries and regions in Europe. Hintermann has completed more than 1,100 TAA procedures. He said he performs them as part of his daily clinical work and other surgeons frequently refer their patients to Hintermann’s hospital.

Jan-Willem K. Louwerens, MD, president of the European Foot and Ankle Society, does 20 to 25 TAA cases a year at St. Maartenskliniek in Nijmegen, The Netherlands. According to Louwerens, there is no exact count of how many TAAs are performed in The Netherlands because no register currently exists. Dan-Henrik Boack, MD, of the Foot and Ankle Center Berlin, Germany, told Orthopaedics Today Europe he treats about 350 patients with ankle arthritis each year and in those he implants about 100 to 120 ankle prostheses. Boack’s practice includes patients from Germany and elsewhere in Europe.

Obstacles to success

Hintermann, Louwerens, Boack and Sunil Dhar, FRCS, FRCS(Orth), of Nottingham University Hospitals in Nottingham, United Kingdom, told Orthopaedics Today Europe the TAA learning curve is steep and an experienced foot and ankle orthopaedist is essential to a successful outcome.

“If you do not balance the hindfoot, if you do not understand what the muscles are doing that are adjacent to the ankle, your ankle replacement may have been put in wonderfully, but it is likely to fail because there are so many other things going on around it,” Dhar said.

To learn the technique, Hintermann recommends performing about 50 of these procedures with an experienced surgeon before attempting one. In fact, Henricson and colleagues who studied 531 TAA cases in the Swedish Ankle Arthroplasty Register reported increased survivorship after Swedish orthopaedists performed their first 30 cases.

Although TAA designimprovements were made after problems with the ball-and-socket ankle prostheses surfaced in the 1970s, design is a factor that remains an obstacle to successful TAA results, Louwerens said. Second-generation constrained two-component polyethylene-on-metal prostheses were associated with many complications, he added.

“With a two-component system, the polyethylene is fixed to the tibial component, so it might be that you have to exchange the tibial component as well, and it is a major surgery,” Hintermann said.

Modern three-component nonconstrained, meniscal-bearing TAA systems introduced in the 1990s have achieved good results, according to Louwerens. The Swedish, Norwegian and New Zealand TAA registers — three of four such registers worldwide — reported average TAA failure rates of 10% in 2007, he said.

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., USA), 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 same 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., USA), the Ankle Evolutive System or AES design (Transystème; Nimes, France), the Hintegra prosthesis (Integra LifeSciences; Plainsboro, N.J., USA) and DePuy’s Mobility device. They reported 78% overall survival at 5 years and 62% survivorship after 10 years.

Other complications

Physicians who spoke with Orthopaedics Today Europe said the complications with which they regularly contend include mechanical loosening following insufficient implant/bone fixation, low grade infection, instability of the artificial joint, asymmetrical polyethylene meniscus wear, bony impingement, malleolar fracture and cystic deformity.

“One of the problems we have not solved yet and we do not fully understand are the cystic deformities in the bone surrounding the prosthesis,” Louwerens told Orthopaedics Today Europe. “Sometimes we think it is polyethylene wear or it might be a form of stress shielding, or a combination, or it is joint fluid getting into these cysts.”

Frequently TAA fails due to ongoing deformity and instability in patients in whom that was present prior to arthroplasty, according to Dhar. “But, there are implants that have … high failure rates because of aseptic loosening and cyst formation and osteolysis around the implant — the AES, which was withdrawn from the market earlier this year,” he said.

Respect the indications

Sources interviewed agreed that the main TAA indication is symptomatic end-stage osteoarthritis, with or without deformity. However, systemic types of arthritis, such as rheumatoid arthritis, may also require TAA, Hintermann said.

TAA is indicated if there are no other reasonable conservative or surgical options, or when these options fail or are no longer acceptable for the patient. In case the ankle is not sufficiently aligned and stabilized, this problem must be solved prior to or in addition to the TAA, Louwerens said. The procedure’s contraindications include infection, poor soft tissue coverage, insufficient bone stock, or older, sick patients with much comorbidity, he said.

In terms of patient age, there are currently no published studies supporting upper or lower age limits or a particular specific gender being associated with better TAA outcomes. Furthermore, the consensus among the surgeons who spoke with Orthopaedics Today Europe was there is no upper age limit for patients undergoing TAA.

Louwerens said older, homebound patients may be more suitable candidates for the procedure since the recovery time is quicker for TAA than fusion, and its 10-year survival rate is good. However, the surgery may also be indicated in younger patients aged from 30 years to 50 years old who are more likely to develop degenerative changes after a fusion, he said.

According to Boack, regardless of age, patients that require a more mobile ankle may be ideally suited for TAA, although he advised against TAA in children who are still growing.

TAA revision may be necessary should problems occur postoperatively. Revisions are commonly performed for pain, loosening, instability, or malalignment, Louwerens said, but he added that there are very few studies detailing TAA revision rates and their outcomes.

When fusion is indicated

Before TAA prostheses and surgical techniques became more commonplace, fusion was the only option for patients. Today, ankle 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,” he said.

A patient’s occupation affects Dhar’s decision for fusion over TAA. Therefore, he does not recommend TAA for patients requiring a lot more motion in their ankle.

“If I get a 60-year-old farmer who is still pretty active, lifts stuff, goes up and down his tractor, and has to walk on uneven plowed land, then clearly an arthroplasty is not going to last him very long,” Dhar said.

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 no significant difference between TAA or fusion in patients with end-stage arthritis.

Allowing activity, sports

Another problem is a lack of evidence for which activities of daily living are advisable following TAA, according to Louwerens. However, he and the other surgeons interviewed noted patients should not attempt anything too dangerous or strenuous after TAA surgery. They recommend some activities based on the local popularity of certain sports. For example, Hintermann allows downhill skiing, walking, bicycling, skiing and tennis, but advises patients against participating in contact or high impact sports.

Dhar allows recreational, but not competitive tennis.

“I prefer [they] perform sporting activities which are either in a straight line, but not high impact, or…activities that [do not] require them to accelerate or decelerate, or twist and turn,” Dhar said.

Use smallest implant size possible

The success of TAA depends on implant type, anatomical positioning of components, patient selection, and using an image intensifier or fluoroscopy for the bony cuts, according to Orthopaedics Today Europe sources. Louwerens and Dhar rely on such imaging to ensure correct component and joint alignment.

However, “if you do not have a normal situation, [such as] deformity, instability, contracted joints, then it is not possible to use the aiming device,” Boack said.

During surgery, Hintermann prefers positioning the patient in the supine position and uses an anterior approach. “You have to plan the surgery carefully with a standardized weight-bearing axis,” he said.

Hintermann also advises against using bulky implants with big pegs, keels, bars or cement.

“The implants are so small, and the surrounding bone is small, when you add cement between the interface and the bone, you automatically increase the size of the implant. The bigger the implants, the bigger are the moments created during gait,” he said.

In the future, implant designs are expected to become more physiological.

“There are actually 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.”

Louwerens expects the number of TAA surgeries performed to steadily increase in the future.

“It is clear total ankle arthroplasty now has a definite place in our armamentarium,” he said. “I have the feeling that in the future, less and less fusions will be performed and more replacements will be done. I do not know how fast this will be. The alternative of fusion is still a very good alternative, [but] people hate the idea of their ankle becoming immobile.” – by Renee Blisard Buddle

Should there be upper and lower age limits for patients eligible to undergo total ankle arthroplasty? Why?

No age limitations needed

My short answer, when it comes to adults, is no.

The discussion has for years been concentrating on the indications, as well as contraindications for total ankle replacement (TAR). Age is just one of several parameters. Suggestions have ranged from 67-year-old and older patients with very limited walking demands to young people performing sports. For elderly patients, a fusion with unloading and 3 months to 4 months in a cast implies a serious impact on their muscle power compared to a TAR with immediate weight-bearing in an orthosis for 3 weeks to 4 weeks. So, for the older generation with end-stage arthritis, sufficient blood supply, and no diabetes, I would certainly recommend a TAR.

On the other end of the scale, it could be an 18-year-old with juvenile arthritis and the usual hindfoot varus. In such cases, I would also perform a TAR and a calcaneus osteotomy, whereas in a soccer player of the same age, other procedures (distraction, osteotomies, even necrotransplants) should be tried instead of TAR. The worries about the young patients are that the TAR will not last a lifetime. This is probably true, but today’s results with a 90% success rate at 10 years, and the option for an ankle fusion later on in case of failure, a TAR as the first choice is probably better than a fusion.

Ankle fusions do lead to secondary degeneration of the neighboring joints after 10 years to 20 years necessitating fusion of these joints, as well. This means that for all patients one must individualize the treatment depending on diagnosis, level of activity, neuromuscular power and mental status. Age is not the limitation.

Hakon Kofoed, MD, inventor of the STAR ankle replacement prosthesis, is at Skodsborg Private Hospital, Skodsborg, Denmark.
Disclosure: Kofoed has no relevant financial disclosures.

Younger age limit may be warranted

The longer life expectancy and higher level of activity in younger patients place higher demands on any total joint replacement. Several total hip and total knee replacement studies report inferior results and higher revision rates in patients aged younger than 55 years or 60 years. There are also several series of total ankle replacement (TAR) reporting higher risk of revision in younger patients. In the Finnish, Norwegian and New Zealand total ankle registers, age did not influence the revision rate. However, in a recent study I and my colleagues conducted using the Swedish Ankle Arthroplasty Register, we found a statistically significantly higher revision rate in patients aged younger than 60 years. Detailed analysis revealed this higher risk only was statistically significant concerning women with osteoarthritis. In patients with rheumatoid arthritis or in men, the revision rate was not influenced by age. Even if there are some medium-term reports of sports activity in patients with TAR, I believe we have to be cautious in patients younger than 55 year to 60 years old, especially in women, at least until we have longer follow-up studies.

Any upper limit concerning age does not seem to be necessary, although severe osteopenia constitutes a contraindication of TAR.

Anders Henricson, MD, is at Falun Central Hospital and Center for Clinical Research Dalarna, in Sweden.
Disclosure: Henricson has no relevant financial disclosures.