What We Don't Know About the Ankle

The ankle is such a small joint for the entire body to walk upon. Why does it rarely get arthritis unless injured?

The ankle joint is a mortise joint, with the talar bone fitting into the tibia. It has a 1 mm tolerance for any irregularity. If the joint or the bones above and/or below are fractured or if the ligaments around the ankle are damaged, the joint can progress down a degenerative pathway to arthritis. Yet if it remains uninjured, people can walk and run on this small joint for a lifetime without ever developing the arthritis that plagues the hips, knees, and other joints.

The articular cartilage (the bearing surface of the ankle joint) looks like the cartilage found in the knee and hip. Yet subtle differences in its thickness, chemistry, and cellular structure probably account for its resistance to arthritis. However, the exact combination of factors is unclear; otherwise, we would reproduce it to repair other joints.

We know that when the ligament around the ankle is loose, surgical repair of the ligament generally works well to tighten up the joint. We also know that when the bones are broken around the joint, a perfect repair must be achieved to avoid eventual joint degradation. What we don’t know is what to do with the arthritic joint.

When most surgeons see a severely arthritic ankle joint, they counsel younger patients to live with it—and the associated pain and loss of motion. Older patients are advised to consider a joint fusion or joint replacement. But neither is an adequate solution. Joint fusion is, in our opinion, a total failure of science. It successfully relieves pain but leads to the destruction of the joints below the fusion due to the lack of normal gait and motion. It is a treatment of last resort. 

Ankle joint replacement has a checkered history, with failures rampant amongst active patients. Over time, the designs have improved and the courage of surgeons to use them has increased. The problem remains that the bones of the tibia and the talar bone of the ankle, once diseased or injured, do not hold the components of the artificial joint well. The surfaces are just too small and the body weight upon them too large.

Bone and cartilage grafting, which amounts to a biologic reconstruction of the ankle, is a technique we have pursued in selected patients—even those with near complete loss of the ankle joint—for the past two decades. The technique requires arthroscopic removal of the damaged surfaces and stimulation of a regenerative process using graft and growth factors. Many of these patients have returned to sports. The number of patients who have had this procedure is too small and too selective to recommend it widely; but since the alternatives are so poor the upside vs. risk seems reasonable. 

Still, even our best biologic reconstruction techniques fail to produce normal ankle joints. The pain is reduced, the motion increased and the return to sports is often satisfying but since our goal is to restore a normal ankle, we still have a ways to go, on a very small but critical joint.

Ankle Replacement or Ankle Fusion. Which to Choose?

Our answer is: Possibly neither. Many people who are told to have an ankle fusion or an ankle replacement, likely don't need one as their next procedure. Biologic therapies are now advanced enough to provide significant relief for many people with severe ankle arthritis. Our BioAnkle program surgically repairs arthritic ankles without any hardware or implants and helps our patients delay—or completely avoid—more drastic, invasive surgeries such as ankle fusion or ankle replacement.