Orthopedic surgeon's new instrument is a refinement on a Pep Boys tool

November 24, 1992|By Knight-Ridder Newspapers

PHILADELPHIA -- Ask a surgeon -- especially a bone man -- precisely what he does and it becomes apparent that he's mostly a craftsman, a mechanic.

"Yes, I'm a carpenter, stone mason and plasterer with a medical degree," orthopedic surgeon Dr. Marvin E. Steinberg says with a laugh.

Hammers, saws, high-speed drills, chisels and screwdrivers are all tools of the trade in the hip replacement game.

So it should be no big surprise that when Dr. Steinberg had an idea for a new surgical instrument, he visited hardware stores searching for something similar.

He found it eight years ago at a Pep Boys store, on sale for $9.99.

It looks like a drill but operates like a small, hand-held jackhammer and is used mostly for removing stubborn mufflers.

It took years for Dr. Steinberg to find a company willing to adapt the tool purchased at Pep Boys into a medical instrument.

About two years ago, Micro-Aire of Valencia, Calif., developed a prototype. Dr. Steinberg has used it often in the operating room with great success.

And now the Steinberg Revision System is about to hit the market. It's somewhat higher in price than the Pep Boys' version -- about $10,000.

What does it do?

It breaks up, and thus makes easier to remove, stubborn old glue from a prior hip replacement.

Dr. Steinberg, 59, is director of the Hip Clinic and Joint Reconstruction Center at the Hospital of the University of Pennsylvania in Philadelphia.

"We've been doing total hip replacements for about 20 years," says Dr. Steinberg. "We're very successful. About 200,000 are done every year nationwide.

"But about 10 to 20 percent fail after 10 or 15 years," he says.

"Even the best car won't last forever."

This is a very good analogy because metal hip joints placed into human bodies look exactly like the ball joints on a car.

In some cases screws -- they look just like regular screws -- hold the ball and socket in place. But in most cases cement is used.

"The cement works very well," says Dr. Steinberg. "It's a quick-setting plastic cement. You mix a powder and liquid and it hardens into Plexiglas.

"That's exactly what it is, Plexiglas.

"We use a device that looks like a caulking gun to get the cement in," he adds.

If and when the replacement fails the surgeon must remove the metal ball and metal and plastic socket, which means chipping away the cement.

And how do you chip away cement connecting the metal hardware to human bone?

With a mallet and chisel and a high-speed drill, of course.

"Using the hammer and chisel and various gouges is slow and laborious," Dr. Steinberg says. "The drill is a little dangerous. You have to be very careful because you can go right into the bone.

"My idea was to combine the advantages of both," he explains. "Combine the hammer principle with power . . . It's a hand-held jackhammer that splits the cement. If you can split it, you can get it out fairly easy with a variety of implements like forceps."

Just using the Pep Boys tool on cement samples in a shop proved to Dr. Steinberg that the principle would work.

Finding a company willing to make the instrument was difficult. The market would be small. The California firm agreed to try it because it already made a somewhat similar device.

The second hip replacement is called a "revision," which explains the name of the new tool.

"It's a longer, more complicated procedure than the first hip replacement that might involve bone drafts," he says.

The Steinberg impacter looks like a handgun with a scope.

The "scope" is a small fiber optic light that helps the surgeon see what he's doing.

Various sizes of chisel and gouge tips can be inserted in the air-powered gun.

Dr. Steinberg says an advantage of his instrument is that it enables one hand to control three functions: power, light and direction.

Naturally Dr. Steinberg is a handy guy and excellent woodworker who, during his leaner years, made all the family furniture.

He's also one of the nation's most experienced and published joint replacement specialists. But this is his first invention.

"I hope it improves the state of the art. That's why I did it," he says. "I don't expect to make much money. I'll get 2 1/2 percent from the manufacturer. But the market is small, a few hundred units at most."

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