Aetna considers total ankle replacement (total ankle arthroplasty) experimental and investigational because its clinical value has not been established.

Total ankle replacement is a procedure in which an injured ankle joint is replaced with a plastic and metal joint. The procedure has been used as an alternative to surgical fusion in patients with loss of ankle function and pain that is refractory to medications, especially because of rheumatoid arthritis. Arthritis from other causes is rarely a reason to do ankle replacement.

Conservative management of ankle pain includes acetaminophen, aspirin, or other medication for pain and inflammation, limiting activity, wearing an ankle brace, shoe modifications, application of heat, and physical therapy.

When conservative measures of treatment fail to provide adequate pain relief, either an ankle fusion or total ankle replacement (ankle arthroplasty) may be considered. Ankle fusion has been the traditional method of treating arthritis of the ankle. In recent years, total ankle replacement has developed as another option. However there is little long-term data on the effectiveness of total ankle replacement. Available data suggests that total ankle replacement has a relatively short lifespan. For this reason, ankle replacements are not usually recommended for people under the age of 50.

The procedure is performed under general or spinal anesthesia. Patients are generally hospitalized for 1 to 4 days. A period of physical therapy is often required after ankle replacement. The patient is able to ambulate within a few weeks following the procedure. The most common complications include thrombophlebitis and pulmonary embolism. Swelling or pressure as a result of the procedure may injure the nerves in the ankle. The new joint can be dislocated rather easily. In addition, there is a risk of infection and hemorrhage.

Encouraged by the excellent results attained by total joint arthroplasty of the hip and knee, several surgeon-engineer teams designed and developed total joint prostheses for the ankle. In the early and middle 1970's reports appeared of early success with these implants in 80% to 85% of patients. In 11 reports that included 346 arthroplasties, good or fair results were reported in 83% and failures in 17% at a mean follow-up of less than 5 years. A wave of enthusiasm developed for total ankle arthroplasty, and the indications for the procedure were expanded, often to include young people engaged in strenuous work or recreational activities. After further experience and longer periods of observation, reviews of most series of total ankle arthroplasties revealed extremely poor long-term results, especially in younger patients with isolated traumatic arthritis. In later reports in which the average follow-up was longer than 5 years, failure occurred in 35% to 76% of arthroplasties.

Comparison of long-term series of total ankle arthroplasty are difficult because of variability in diagnosis, patient age, length of follow-up, prosthesis design, and absence of a uniform scoring system. The largest series of total ankle arthroplasties is that of Kitaoka et al. (1994, 1996), who reported their experience with 204 primary Mayo total ankle replacements. The overall cumulative rate of implant survival was 79% at 5 years, 65% at 10 years, and 61% at 15 years. The probability of an implant being in place at 10 years was 42% for patients 57 years of age or younger and who had previous operative treatment of the ipsilateral ankle or foot and 73% for those older than 57 years of age who had no such previous operative treatment. Because of these poor long-term results, they do not recommend the use of the Mayo total ankle arthroplasty, especially in younger patients who have had a previous operative procedure on the ipsilateral ankle or foot. In a series of 36 constrained Conaxial (Beck-Steffee) ankle replacements, Wynn and Wilde (1992) found that 27% were loose at 2 years, 60% at 5 years, and 90% at 10 years; they recommend that this ankle prosthesis not be implanted.

Complications other than implant loosening also are more frequent after total ankle arthroplasty than after total hip or knee replacement. Delayed wound healing has been reported to occur in as many as 40% of patients, and most long-term series cite rates of deep infection of 3% to 5%. Loosening has been reported in 6% to 25% of implants after 3 to 5 years; usually the talar component is involved. Demottaz, et al. (1979) reported radiolucent zones of 2 mm or more at the cement-bone interface in 88% of prostheses at 1 year, and Unger et al. (1988) reported talar subsidence in 14 of 15 arthroplasties and tibial component tilting in 12 of 15 at an average 6-year follow-up. Wynn and Wilde (1992) reported an overall complication rate of 60%, including wound dehiscence (39%), deep wound infection (6%), fractures of the medial or lateral malleolus (22%), and painful talofibular impingement (14%).

Although some more recent reports of uncemented, unconstrained replacements have shown better short-term results, currently no ankle implants are available that provide consistently good long-term results. There are no prospective randomized controlled clinical trials comparing total ankle replacement to fusion or other alternatives. In a review of total ankle arthroplasty, Saltzman (1999) concluded that despite efforts to develop a workable total ankle replacement the long-term results of most new designs are unknown. Saltzman concluded that prospective clinical trials are needed to determine which factors lead to successful and unsuccessful outcomes.

A 2003 AOFAS position statement on total ankle arthroplasty stated that ankle arthritis has many treatment options, both operative and non-operative. Operative treatment is available for patients with persistent symptoms. Surgical options include joint debridement, distraction arthroplasty, osteotomy, ankle arthrodesis and total ankle arthroplasty. Total ankle arthroplasty is a viable option for the treatment of ankle arthritis. However, this position statement does not appear to be substantiated by a vigorous assessment of the technology.

In a review on total ankle replacement, Hintermann and Valderrabano (2003) stated that although the results of the different design approaches are encouraging in limited clinical series, there is still the need for careful, long-term analyses to estimate to what extent the current designs are mimicking the biomechanics of the ankle joint. More attention must be paid to more accurate implantation techniques that result in a well-balanced ligament and allow the ligaments to act together with the replaced surfaces in a most physiological manner. Gill (2004) noted that there is a need for further basic science research in total ankle arthroplasty. The lessons learned from other arthroplasty should be considered in ankle arthroplasty design.

Spirt et al (2004) reported a relatively high rate of re-operation after total ankle arthroplasty with a second-generation total ankle replacement device -- the DePuy Agility Total Ankle System. Younger age was found to have a negative effect on the rates of re-operation and failure. Most prostheses could be salvaged; however, the functional outcome of this procedure is uncertain. Haskell and Mann (2004) tested the hypotheses that pre-operative coronal plane mal-alignment and incongruence of the ankle can be corrected and maintained for 2 years with total ankle replacement. These investigators found that patients with pre-operative incongruent joints are 10 times more likely to have progressive edge-loading develop than patients with congruent joints. They state that surgeons must be attentive to coronal plane alignment during and after ankle replacement, and that longer follow-up is needed to assess the longevity of the correction and the impact of minor mal-alignment on implant wear.

Easeley et al (2002) stated that four 2nd-generation total ankle arthroplasty designs have shown reasonable functional outcomes: (i) the Scandinavian Total Ankle Replacement, (ii) the Agility Ankle, (iii) the Buechel-Pappas Total Ankle Replacement, and (iv) the TNK ankle. They noted that intermediate results are promising but should be interpreted with care. Knecht et al (2004) stated that arthrodesis of the tibiofibular syndesmosis impacts the radiographical and clinical outcomes with the Agility total ankle replacement. The relatively low rates of radiographical hind-foot arthritis and revision procedures at an average of 9 years after the arthroplasty are encouraging. Agility total ankle replacement is a viable and durable option for the treatment of ankle arthritis in selected patients.

On the other hand, in a cost-effectiveness analysis of total ankle arthroplasty, SooHoo and Kominski (2004) stated that the currently available literature has not yet shown that total ankle arthroplasty predictably results in levels of durability and function that make it cost-effective at this time. However, the reference case of this analysis does demonstrate that total ankle arthroplasty has the potential to be a cost-effective alternative to ankle fusion. This reference case assumes that the theoretical functional advantages of ankle arthroplasty over ankle fusion will be borne out in future clinical studies. Performance of total ankle replacement will be better justified if these thresholds are met in published long-term clinical trials. Furthermore, Stengel and associates (2005) performed a meta-analysis of studies exploring the effectiveness of 3-component total ankle prostheses for treating end-stage ankle arthritis of different origin. These investigators concluded that ankle arthroplasty improves pain and joint mobility in end-stage ankle arthritis. Its performance in comparison to the current reference standard (i.e., ankle fusion) remains to be defined in a properly designed randomized trial.