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How One Bad Turn Leads to Another

Once sprained, an ankle becomes prone to repeat injuries. It's just part of how the body works, but the vicious cycle can be broken.

July 08, 2002|MARLENE CIMONS | SPECIAL TO THE TIMES

Have you ever wondered why, whenever you sprain your ankle, it's always the same one?

It's no coincidence: The biggest risk for suffering an ankle sprain is having had one already.

The reason for this is a little-known phenomenon known as proprioception. This tongue twister of a term refers to a human body's intuitive ability to know where it is in time and space without directly looking, like being able to walk a straight line without looking down. It's a fine-tuned coordination that each of our joints has, an innate ability to instantly shift the body in an unconscious and instantaneous course correction to keep it centered.

It affects the performance of all of the joints in the body, although we rarely are aware of it. We may glance down when shaking someone's hand, for example, "but the professional handshake is perfected when you look someone in the eye," says Dr. Glenn Pfeffer, a San Francisco orthopedic surgeon. "Can you imagine what would happen if every time we went to shake someone's hand, we missed?"

Some people are better at it than others, just as with any natural physical skill, and this ability can diminish with lack of use--such as when someone breaks a bone and spends weeks or months in a cast. Tightrope walkers, long jumpers, ballet dancers, cross-country runners, for example, have heightened proprioception.

These athletes and artists perfect these intuitive skills through high levels of training for their sport, or their craft. But proprioception is an ability that actually develops in early childhood. "Watch a 1-year-old learn to walk: He looks down at his feet," Pfeffer says. "We, as adults, don't do that because we have developed our proprioception."

So what, then, does this have to do with ankle sprains?

While every joint in the body is affected by proprioception, it plays an especially important role in weight-bearing joints such as ankles or knees. "The hands and arms don't have joints that control your full body weight, unless you are doing handsprings all the time," says Dr. Nicholas DiNubile, a Pennsylvania orthopedic surgeon who is a consultant to the Philadelphia 76ers basketball team and the Pennsylvania Ballet.

Moreover, it is a key factor in whether, once injured, we are prone to re-injure those same joints again.

Every ligament in your ankle has thousands of nerves, and every time you hit uneven ground, a curb in the street, a crack in the sidewalk or a branch snaking across a hiking trail, your brain performs millions of calculations to ensure that your foot lands properly.

When you sprain an ankle, the key nerves that regulate this process are damaged, altering the body's ability to perform this function. As a result, if you don't do something to retrain those injured nerves, you're more likely to sprain that same ankle repeatedly.

What we think of as a floppy or loose ankle that results from the first sprain is actually a slowdown in the feedback loop between the nerves in the foot and the brain. The brain can't react quickly enough to prevent that ankle from being re-injured.

When the already vulnerable foot lands unevenly, and the ankle starts to turn, the proprioceptors--the part of the nerves that tell the ankle where it is in time and space--send a message, in effect, to the muscles: "Go back, go back." But often the message comes too late, health experts said.

The foot doesn't know quite where it is when it plants on the ground, and can't adapt to variations in ground surface.

And a vicious cycle begins. This is one of the reasons ankle sprains are among the most common injuries afflicting Americans, even among people who don't regularly engage in sports or other exercise. About 27,000 ankle sprains occur every day in this country.

An ankle sprain can happen during routine activities, such as stepping off a curb, just as easily as during exercise, particularly among those with earlier sprains. Sometimes the cause is not apparent. The ankle turns, and the person falls, utterly baffled as to exactly what he or she did to cause the sprain.

The ankle joint is made up of bones held together by ligaments--think of how a hinge keeps a door connected to the wall. In a mild sprain, the ligaments are just strained or stretched; with a moderate sprain, they are partially torn. And in the worst case, a severe sprain, the ligament is completely torn and no longer able to control the ankle joint.

The vast majority of ankle sprains are inversion sprains, meaning the foot turns inward, injuring the ligaments on the outside of the ankle. This occurs because of the way the ankle is built.

"The muscles on the outer part of the leg tend to be weak; there is a large muscle imbalance between the muscles on the outside of the leg versus the muscles on the inside of the leg," says Janet Sobel, a Chevy Chase, Md., physical therapist who treats many athletes. Because of this, she says, "if it's going to sprain, it's usually going to turn in."

Treating an Injury

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