Ankle Fusion Surgery for Arthritis

Although arthritis in the knees, hips, and hands gets most of the attention, arthritis in the ankle is a serious and relatively common condition. In fact, about 50,000 new cases of ankle arthritis are diagnosed every year in the United States. Of these, 70% are caused by trauma to the ankle. A sports injury or other significant trauma can raise the risk that the ankle will develop arthritis later on. In other cases, ankle arthritis is due to rheumatoid arthritis (RA) or primary osteoarthritis (OA) that isn’t a result of past injury. Whatever the cause of ankle arthritis, there are treatment options that can effectively relieve pain and restore the function of the joint, such as ankle fusion surgery.

Our ankles bear the full weight of our bodies, and problems with them can have a profound effect on our quality of life. Pain and stiffness in the ankle can make it difficult to perform even the simplest activities, such as walking to the car or taking a stroll around the block. Stairs in particular can be a problem. Possible signs of arthritis in the ankle include stiffness and swelling and pain during walking.

Before discussing the treatments that can help you manage your ankle arthritis, let’s review the anatomy of the ankle and discuss what happens when the ankle joint has arthritis.

Anatomy of the ankle

The ankle is the meeting place of three bones. The two bones in the lower leg, the tibia and fibula, form a mortise-shaped joint with a bone from the foot called the talus. The positioning of the bones allows the ankle to move forward and backward but limits side-to-side motion. (The majority of the foot’s side-to-side motion comes from joints just in front of and below the ankle.) As with all mobile joints in the body, the ends of the bones that meet to form the ankle joint are covered with cartilage, and the joint space is filled with a viscous fluid. The cartilage serves to cushion the impact on the bones when you walk, run, and jump. With the fluid, it makes a nearly frictionless surface for the bones to glide across one another, reducing wear and tear during motion. The bones in the ankle joint are held together by ligaments, and the muscles in the lower leg, which attach to bones in the foot, are responsible for moving the joint.

Ankle arthritis occurs when this finely tuned system breaks down. For example, an injury to the ankle can cause unusual pressures to be placed on the joint. As a result, the cartilage between the bones can break down, allowing bone to rub on bone and causing pain, stiffness, and loss of mobility. This condition of cartilage breakdown after an injury is known as secondary OA (also called posttraumatic arthritis). In RA and other types of inflammatory arthritis, damage to the ankle joint is a result of body-wide inflammation that erodes the cartilage and other structures in the joint.

It is important to recognize that although there are many different types of ankle arthritis, the available surgical options for each type are similar.

Conservative treatment versus surgery

If you are experiencing constant ankle pain, it is important to seek out a medical professional (preferably an orthopedic surgeon, a doctor who specializes in surgery for skeletal disorders). The doctor will take x-rays to help diagnose your condition. If you are diagnosed with ankle arthritis, you should start with conservative treatment before rushing into surgery. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin IB) or naproxen (Aleve) can be helpful for relieving pain and inflammation. Wearing different shoes, such as ones with a softer, more shock-absorbing sole, or perhaps with a rubber rocker bottom design, can be helpful, as long as you are able to maintain good balance. The MBT brand of shoes or Skechers Shape-Ups are examples of shoes with rocker bottoms, but for some people these shoes may “rock” too much. As an alternative, milder rockers can be glued onto the outer soles of many shoes. The key is to make walking easier without compromising your balance.

If the conservative treatments described above are not effective, surgery may help. However, it isn’t for everyone. A fear of anesthesia, complications, or infection may deter some people, though the risk of these problems is small. If you feel apprehensive about having surgery, your best bet may be to try to adjust your lifestyle to accommodate your arthritis and maintain your ability to walk. If you try conservative treatment but still have a lot of pain or difficulty walking, then you and your doctor should consider ankle surgery. Below, we review three types of surgery for severe ankle arthritis: ankle joint distraction, ankle fusion, and total ankle replacement.

Ankle joint distraction

Some people choose to try a procedure called joint distraction to treat their ankle arthritis. In joint distraction, a doctor puts a frame that looks a bit like an Erector Set around your ankle. Surgical wires attached to the frame are then inserted through the skin and attached to the bones. The tension created by the frame and the wires holds the ankle joint open so that the bones are not rubbing against one another. The frame is left on for several months while the wearer moves around and bears weight on the joint. The goal is to allow the ankle to move while normal pressures are taken off the joint. Early studies of joint distraction have shown that it can reduce pain, although it can take a year to feel the benefit, and some pain may remain afterward.

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

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.

Total ankle replacement

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.

What is the best choice for you?

If you are considering ankle surgery, you are probably asking yourself the following question: To fuse or not to fuse? As with any surgery, you and your orthopedic surgeon need to carefully consider the particulars of your situation. The following information can help you make an informed decision.

The state of the joint plays a critical role in determining the right type of surgery. If your foot or ankle has severe deformities, these deformities can put abnormal stresses on an ankle implant and result in early failure. Fusion may be a better choice in this situation. However, people who are 50 or older and whose ankle joint is well-aligned are often reasonable candidates for ankle replacement. People with arthritis in joints surrounding the ankle can be particularly appropriate candidates because a fusion would place extra stress on those surrounding arthritic joints.

Age is a big factor. In people under the age of 55, ankle fusion is often the best option because young people will put more stress on their ankle and are more likely to outlive an implant and need revision surgery down the road. People older than 55 are better candidates for ankle replacement because they will typically put less stress on an implant and are less likely to wear it out.

Body weight is a third important factor to consider when deciding between ankle fusion and replacement. Someone who is overweight or obese will exert more force on a replacement joint than someone of average weight. The increased stress on the implant may wear it out or loosen it much more quickly than usual. For overweight people, fusion is often a better choice, although being overweight can exacerbate the problem of placing additional stress on joints near the fused ankle joint, leading to problems with those joints.

Finally, you should consider your lifestyle. An active lifestyle requires more movement and thus a more mobile ankle joint. In this case, an ankle replacement may be most appropriate. However, very vigorous activities (especially running, jumping, and manual labor) are likely to wear down or loosen the implant. Because of the many different variables you must consider before deciding on surgery, it is essential that you receive a consultation from an orthopedic surgeon. If possible, you should see an orthopedic surgeon who specializes in the foot and ankle, and the surgeon should perform an examination of your ankle and the nearby joints. Ask your primary-care doctor to recommend an orthopedic surgeon, or go to the American Academy of Orthopaedic Surgeons Web site to search for one in your area.

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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