SHIN SPLINTS Too much muscle in too little space


YOU DON'T GET shin splints if you're in good shape, Jack Lawrence kept telling himself. And several years ago, the Toronto businessman and life-long athlete, then 49 years old, was definitely in shape: Regular games of squash, five-mile runs and the occasional marathon helped keep him that way.

Yet something was undeniably wrong with his legs.

"Every time I ran, I felt a tightness and soreness in my shins," Lawrence remembers. He consulted a physical therapist, who said he probably had a case of "regular shin splints," although she, too, was surprised that a fit athlete would get them.

What the therapist didn't tell him was that the term shin splints covers a grab bag of ailments ranging from stress fractures in the shin bone to damage to the membrane covering it.

The therapist suggested ultrasound treatments to increase blood flow to what she believed was damaged tissue, removing waste products and speeding healing. That didn't help, so Lawrence went to see a physician. When X-rays failed to show any bone fractures, the doctor gave him a shot of anti-inflammatory cortisone, another common shin splint treatment. That didn't help either.

"I reduced my mileage a little and didn't run up any hills, but it kept getting worse," Lawrence says. "Even if I played golf, my shins would be quite sore. Even when walking."

He saw three more doctors before an orthopedist at the University of Western Ontario was able to tell him he was suffering from a strangely named type of shin splint called chronic compartment syndrome.

And Lawrence was lucky, according to a University of Wisconsin at Madison study of 100 people with the syndrome. Those patients spent an average of 22 months seeing as many as 10 doctors before getting an accurate diagnosis.

Christine Hekhuis, a 37-year-old Virginia woman, had compartment syndrome for several years yet didn't run at all. She swam and worked out on a NordicTrack machine.

Still, Hekhuis recalls, "any kind of walking for more than 15 minutes would make my legs hurt" with a burning pain running down the outside of both shins.

Muscles lie in anatomical "compartments" bounded by walls of connective tissue called fascia. There are seven compartments in the lower leg. During exercise, increased blood flow causes muscles to expand against the fascia, which then stretches a bit. That's normal.

But some people, such as Lawrence and Hekhuis, are born with particularly small compartments. As muscles grow larger with repeated exercise, they push longer and harder against the fascia, which toughens like a skin callus. The expanding muscle ends up squeezed against the stiff walls, raising pressure in the compartment and causing soreness.

The pain's location is an important clue.

"People with this syndrome feel it equally throughout the entire compartment," says Lawrence Lutz, a physician at the University of Colorado Health Science Center.

"When you ask specifically, 'Where does it hurt?' they'll draw an outline of the compartment." The pain of muscle tears and bone fractures tends to be felt most sharply in one spot.

"Typically, people have been running for months or even years before the pain becomes a problem," says Don E. Detmer, a vascular surgeon at the University of Virginia Health Science Center. It tends to affect both shins at once.

The conclusive test is to measure the pressure in the compartment. For this, physicians use a regular syringe with a little fluid in it. The doctor inserts the needle into the compartment and notes the pressure needed to push the fluid out. The highest normal pressure for someone who walks into a doctor's office is about 15 millimeters of mercury, and people with compartment problems usually show readings well above that.

Getting it is mostly a matter of having small compartments to begin with, says Detmer, "and then doing things that will bring it forth."

The most effective treatment for most sufferers is minor surgery. Using local anesthesia, usually, a surgeon makes a small incision in the leg, then cuts the fascia of the affected compartment and lets the sides of the incision spread, opening a narrow, oblong window. The idea is to open it enough to let the muscle expand, yet still leave fascia to hold the muscle bundles in place.

As the fascia heals, new tissue forms in the gap. "You more or less put a gusset in the fascia," says Detmer, comparing the process to enlarging a dress by sewing in a new piece of material.

It's also helpful for runners to cut back on the mileage when symptoms first appear, Detmer says, before the fascia gets really tough and inflexible.

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