Here's a step-by-step setup to president's knee injury Hopkins surgeon describes how it happens, its repair

March 15, 1997|By Jonathan Bor | Jonathan Bor,SUN STAFF

President Clinton's stumble on the staircase was a classic setup for a quadriceps tendon tear, a painful injury that makes it impossible for someone to extend the leg to bear weight.

Although not rare, it is not one of the more common knee injuries. In 1994, about 7,000 people were admitted to U.S. hospitals with this problem -- about one-seventh the number who were admitted with torn knee ligaments.

The quadriceps tendon is a broad bundle of fibers that connects the quadriceps -- four large muscles running down the front of the thigh -- with the top of the kneecap. One can easily feel it straightening the leg and pinching the area just above the knee.

"When you're going up the stairs, the quadricep is actively extending the knee to propel you up the step," said Dr. David S. Hungerford, professor of orthopedic surgery at the Johns Hopkins University School of Medicine. "When you're going down, it's letting go in a controlled way."

Descending a staircase is much like lowering a heavy weight over a pully, he said. The person lets the weight down gently, releasing and "hanging on" at the same time.

"When you stumble, you accelerate your body mass." You put out a foot to break your fall, but the quadriceps bear most of the weight. In some cases, the energy of the falling weight overcomes the strength of the tendon -- and it snaps. "It is physically ripped off the bone," Hungerford said. "There's a mechanical disruption. The muscle is no longer attached to the bone."

Doctors described the president's injury as more than a 50 percent tear, meaning more than half the tendon fibers tore off while the rest remained in place.

The injury can occur during racquetball or tennis, sports that can require sudden starts and stops. A perfect scenario is a place kicker extending his knee to boot a football but accidentally jabbing his toe into the earth. Two other injuries can occur in such cases. The tendon that connects the kneecap to the lower leg can tear. Or the kneecap can shatter.

To repair the knee, surgeons stitch the tendons to a few holes drilled into the top of the kneecap. The knee is protected in a splint, cast or brace. With the aid of crutches, the person can bear some weight and walk.

"You would expect a full recovery," Hungerford said.

Clinton's surgery lasted two hours, and he is expected to need six months of physical therapy before regaining full use of his knee.

Pub Date: 3/15/97

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