Treatment for hips and knees worn down by arthritis is usually straightforward: joint replacement surgery. But surgical solutions for osteoarthritic ankles are less clear-cut. That's because most traditional methods relieve pain at the expense of long-term joint health. Joint repair through joint distraction arthroplasty may offer the best solution.

Traditional repair methods such as fusion – or arthrodesis – require bones in the ankle and leg to be permanently locked together with plates and screws. Pain relief can be dramatic, but it comes at a price: an abnormal gait, potential arthritis in nearby joints and an ankle too immobile for sports or climbing stairs.

The alternative is an artificial joint, similar to a hip or knee implant. Ankle replacement is more complicated though, and requires a high degree of surgical skill. Ankle implants also tend to wear out quickly, making them a poor choice for the younger, more-active patients who often need them.

"Most people with knee arthritis are in their 60s and thinking about retirement, whereas ankle arthritis frequently strikes people in their 40s who need to function and provide for their families," explains Gregory C. Berlet, MD, an orthopaedic surgeon at the Orthopaedic Foot and Ankle Center in Columbus, Ohio.

Some doctors advise younger patients to grin and bear it until a better option comes along.

But that option may already exist. Called joint distraction arthroplasty, it uses the body's natural repair mechanisms to heal the joint without damaging it.  

Distraction involves pulling the joint surfaces slightly apart and holding the bones in place with pins set in an external fixation frame. The theory is that the absence of mechanical stress on the joint combined with changes in intraarticular fluid pressure allows damaged cartilage to repair itself, explains Austin T. Fragomen, MD, director of the Limb Lengthening Clinic at Hospital for Special Surgery (HSS) in New York City and assistant professor of orthopaedic surgery at Weill Cornell Medical College.

HSS physicians have used distraction arthroplasty for ankle arthritis for a decade and recently began using it for knees.

The procedure itself is relatively straightforward. Surgeons remove any bone spurs – growths common in ankle arthritis – and drill small holes in the bone (called microfracture) to help stimulate cartilage repair.

"These are standard procedures we've been doing for dozens of years with mediocre results," Dr. Fragomen says. "What is exciting is adding distraction to it."

The next step is assembling the frame, which is composed of one or more rings, about six inches in diameter, that encircle the ankle like a halo. Pulling the rings apart and locking them stretches the joint surfaces about 5 millimeters – less than a quarter inch.

Mesenchymal stem cells from the patient's bone marrow are used to jumpstart the repair process. Because they can transform into cartilage cells, stem cells are often used in orthopaedic surgeries.

"We're constantly tweaking the way we use stem cells," Dr. Fragomen says. "We have the option of just injecting them into the ankle, putting them into a fibrin matrix, which is like sticking them in jello, or we can mix them with small pieces of [donor] cartilage in hopes that will help form an even better layer of new cartilage."