Presented by: Kenneth Hunt, MD
Assistant Professor, Orthopaedic Surgery
Stanford University Medical Center
October 13, 2010
- Over time the ankle’s bone surfaces become worn, resulting in arthritis.
- The most common cause of ankle arthritis is previous injury.
- Ankle joint replacement works well in some cases, replacing the damaged ankle joint with an artificial implant.
- Fusion remains the standard of care for many patients.
- Ankle replacement implants are showing increasingly positive results.
More than 50 million Americans suffer from some form of arthritis-about 22 percent of the country’s population. Between 6-13 percent of those people have ankle arthritis. Because the ankle is highly constrained, with bone on all sides, it requires the cushioning of cartilage for smooth movement and range of motion. Over time the joint surfaces become worn, resulting in inflammation, swelling, and pain in the joint.
“There’s a lot of stress on the ankle,” said Kenneth Hunt, MD, an assistant professor of orthopaedic surgery, who spoke at a presentation sponsored by the Stanford Health Library. “The ankle has half the thickness and half the surface area of the knee, yet receives a force of up to five times your body weight with each step.”
The most common cause of ankle arthritis is previous injury. About 70 percent of all cases arise from an injury causing the cartilage to be damaged. Ankle sprains are the most common foot injury, often caused when the when the foot is inverted beyond the control of the ligaments or muscles. “Sprains are often inadequately treated, which can lead to more problems later on,” said Dr. Hunt. “It’s relatively easy to damage the cartilage with ankle injury.”
Another possible cause are osteochondral defects of the talus or tibia (OCD): A bone bruise from a chip or cyst on the anklebone (the talus) that leads to softening of the cartilage. Though there is no proof of a direct link between OCD and ankle arthritis, Dr. Hunt said it may be a precursor to the condition in young people and should be checked regularly.
Symptoms of ankle arthritis include pain, stiffness, swelling, and limitations in movement. X-rays can show changes in the spacing between bones or in the shape of the bones themselves and are usually clear enough that more detailed imaging, like CT or MRI, is not required.
“The first line of treatment is non-surgical,” said Dr. Hunt. “The goal is to reduce pain and to preserve function and range of motion.”
First steps may include limiting activities, if possible, and using boots, braces, or orthotics. Wear sensible shoes, and look into specialty shoes with rocker bottoms to help propel you forward as you walk. Walkers and canes may also be useful to help take pressure off your ankle. Physical therapy can help with strength and stability, but because there is little or no cartilage, certain movements can cause flare-ups.
Medications include anti-inflammatories, NSAIDs (aspirin or ibuprofen), steroids, or acetaminophen (mild painkillers like Tylenol or Anacin). Studies have shown that weekly injections of hyaluronic acid improved the condition, with no side effects, but more long-term data is required, Dr. Hunt said, before this approach can be applied broadly.
When lifestyle changes and medication are not enough, there are several surgical options.
The most common surgical option is fusion, which uses pins, plates, screws, or rods to hold the bones in place while they heal together. Though both durable and successful, fusion does affect the gait since it limits the ankle’s up-and-down motion. It also is related to adjacent joint arthritis in 90 percent of patients 20 years later.
“Fusion remains the gold standard of care,” said Dr. Hunt. “It usually lasts a patient’s lifetime. And having a fusion does not necessarily mean you will walk unnaturally. It remains the procedure of choice for many patients.”
Although not as common as total hip or knee joint replacement, advances in implant design have made ankle replacement a feasible option for many people. Arthroscopy works well in cases of isolated cartilage injury or osteochondral defects. In addition to providing pain relief, ankle replacements provide better mobility and movement compared to fusion.
Today there are 20 ankle replacement products worldwide-five of which are approved by the FDA for use in the United States. All are equal in in terms of quality and longevity (about 10-15years for most patients), Dr. Hunt said, so ask your orthopaedic surgeon which implant he or she is most experienced in using.
Total ankle replacements work best on patients with minimal bone deformity, who are age 50 or older, in good shape (not obese) but not a hard-core athlete. Studies comparing implants with fusion found that patients with implants had higher satisfaction and mobility, but more complications. While improvements continue, there is still very little data on long-term results, although Dr. Hunt said the results so far have been very encouraging.
About the Speaker
Kenneth Hunt, MD, is a specialist in foot and ankle reconstruction and in treating lower extremity trauma and deformity. He received his MD from the University of Utah School of Medicine and completed his internship and residency at the University of Utah. He did his fellowship training in foot and ankle reconstruction at Orthocarolina and Carolinas Medical Center in North Carolina. Dr. Hunt joined Stanford in 2009.
For More Information:
About Dr. Hunt
Stanford Orthopaedic Surgery & Sports Medicine
American Academy of Orthopaedic Surgeons