by Benjamin R. Williams, BS, and Jonathan T. Deland, MD
Ankle joint distraction is relatively new and is not for everyone. Young people with severe ankle arthritis are most likely to benefit. More studies need to be done to prove the technique’s long-term effectiveness.
Ankle fusion is the most common surgical treatment for ankle arthritis. This operation has been in use for many decades, so we have good long-term information on its success. In an ankle fusion, cartilage is removed from the talus and tibia, and the bones are compressed against one another in a position that allows for walking. Screws or other fixes are then used to hold the bones in place while they fuse. (See an illustration.) Rehabilitation after an ankle fusion involves using crutches to keep the weight off the foot for two to three months until the tibia and talus are fused.
Ankle fusion is usually used in people with RA. Between 80% and 90% of people who have an ankle fusion experience a significant decrease in their pain and feel the operation was a considerable help. It may seem as though an ankle fusion would cause a complete loss of the motion used for walking, but in fact, the ankle joint is only one of several joints in the foot used for walking. Joints below the ankle and in front of the ankle also contribute to motion during walking. As long as the joints surrounding the ankle are mobile and in good shape, the ankle can retain a surprising amount of mobility after an ankle fusion.
A downside to fusing a joint is that it puts increased stress on the neighboring joints. By removing the motion of a joint, the forces that would normally go through that joint are placed on nearby joints. The result is an increased risk of arthritis in the joints around the ankle. Studies show that eight years after an ankle fusion, over 50% of people show some sort of arthritis in the joints around the ankle. And 20 years after surgery, almost all of them have some form of arthritis in the joints around the ankle, although those joints may not be painful at the time. Despite this risk, the majority of people who have had an ankle fusion are much happier than they were before, as long as their ankle was positioned correctly and successfully fused and their other joints are in good condition.
In recent years, total ankle replacement has become a reasonable alternative to ankle fusion. This was not always the case. The first ankle replacements were introduced in the 1970’s, and the results were not positive. Since then, better replacements have been and continue to be designed, and the results of the surgery have significantly improved. At the moment, there are several types of replacement joints on the market, all with somewhat different designs. But compared with the earlier models, today’s devices have much better shapes and produce better results. The ability to fix the implant to the bone is also improving as new fixation methods and materials are developed. We know that ankle replacements can last for 10 years in most recipients; after 7–10 years, about four-fifths of implants remain successful. Longer-term studies are in progress.
In a typical ankle replacement, an incision is made above the ankle, and the damaged cartilage and some bone from both the tibia and talus are removed. The amount of bone removed varies depending on the type of ankle replacement used. Usually two metal pieces, a tibial and a talar component, are fixed to the respective bones. A plastic bearing piece can then be attached to the tibial piece or just placed in between the two metal pieces. (See an illustration of an ankle replacement.)
Recovering from a total ankle replacement requires some time and commitment. It usually involves staying off your feet for several weeks, followed by exercises to move the ankle forward and backward before progressing to full weight bearing at 6–10 weeks after surgery.
Recent improvements in the design of ankle replacements have made it a more reliable solution for people with ankle arthritis. In a study recently presented at the annual meeting of the American Orthopaedic Foot and Ankle Society, researchers compared people who had an ankle fusion with people who had an ankle replacement. Two years after their surgery, people who’d had an ankle replacement functioned better in their daily lives than those who’d had an ankle fusion. It is important to note that two years is a very short period over which to measure effectiveness. Studies of newer ankle replacement designs that follow recipients for more than 10 years are not yet available. As with the other surgical options discussed in this article, ankle joint replacement may not eliminate joint pain or discomfort altogether.
Last Reviewed on September 7, 2011
Benjamin R. Williams is a research assistant and Jonathan T. Deland is Chief of the Foot and Ankle Service, both at the Hospital for Special Surgery in New York City. Dr. Deland has acted as a consultant in the production of a new ankle implant from Zimmer.
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