Is Total Ankle Replacement More Effective Than Ankle Arthrodesis?
With advances in the design of newer generation ankle implants, an improved understanding of the biomechanics involved with this procedure and a reduced risk of long-term complications, this author says total ankle replacement is increasingly becoming the procedure of choice for properly selected patients with end-stage arthritis.
By Lawrence A. DiDomenico, DPM, FACFAS
This year in the United States, the use of total ankle joints is expected to increase. According to industry estimates, over 4,000 patients are anticipated to undergo surgical treatment this year for ankle joint replacement.
Presently there are five FDA-approved ankle implants in the U.S. Four of these implants are commonly used in the U.S. and there are over 30 ankle implants currently being utilized in Europe. The demand for total ankle replacement in the U.S. is projected to grow as more and more baby boomers age with debilitating ankle pain.
The ideal patient for ankle joint replacement is someone who is older (preferably around retirement age), thin, active and with low physical demands. Today, the efficacy of total ankle replacement in comparison with that of ankle fusion continues to be one of the most debated topics in foot and ankle surgery.1
Key Insights On The Evolution Of Total Ankle Replacements
Ankle replacement was first introduced to the U.S. in the 1970s. In the past, total ankle replacements had an unfortunate history stemming from poor mechanical designs and the operating physicians had limited experience. At that time, early reports on total ankle replacements appeared to be promising.2
However, shortly after these reports, long-term follow-up studies highlighted many failures and poor survivorship of the implants. This led many surgeons to abandon the procedure in favor of arthrodesis as it has now become very dependable with limited complications.3-5
There are a couple of things to bear in mind with the early history of total ankle replacement. In the 1970s and 1980s, many of the surgeons implanting total ankles in the early years were not foot and ankle surgeons. Balancing the biomechanics of the foot and ankle was not well understood or consistently done.
The poor performance of these older ankle implant designs and a lack of understanding of the biomechanics, coupled with use by general (non-specialist) surgeons, resulted in a negative stigma. This consequently made ankle fusion the treatment of choice.
Indeed, problems with early implants left surgeons and patients cautious. Until recently, this patient population had limited surgical options: ankle arthroscopy, ankle arthrodiastasis and ankle fusion for end-stage arthritis.
Ankle fusion typically relieves pain but these patients lose mobility in the ankle. This leads to changes in gait and, ultimately, additional wear and tear causing arthritic pain in other areas of the local anatomy. In 2009, approximately 25,000 people out of 50,000 potential candidates underwent ankle fusions.
However, with an improved understanding of biomechanics and surgeons learning from previous implant failures and successes, total ankle replacement is becoming the procedure of choice for certain patients with end-stage arthritis. The new generation of ankle implants has an improved anatomical design and there is a better understanding for the need to balance the foot and ankle.
In addition, the surgeons implanting these ankle replacements are foot and ankle surgeons. Accordingly, the implants are becoming an increasingly more popular and successful alternative to ankle fusion.
What About Long-Term Complications?
Ankle arthrodesis remains a steadfast surgical procedure of choice for end-stage arthritis. The short-term outcomes of ankle arthrodesis are vastly improved, particularly with nonunion rates because of improved internal fixation and better surgical techniques. Most reports suggest the average time to fusion is approximately 10.5 weeks, the average fusion rate is almost 93 percent and patient satisfaction rates are almost 90 percent.6