Artificial-Limb Gains Put Some Spring in Step

When Bob Singer jumped on a pogo stick in a ballroom Friday at the Marriott Hotel in Newport Beach, a crowd quickly gathered to watch.

The attraction, however, was not the sight of a full-grown, slightly paunchy public relations man bouncing about on a child’s toy. The attraction was the pogo stick’s foot, complete with sole, heel, ankle, and five toes with simulated toenails and cuticles.

As Singer bounced, the artificial foot, which had been attached to the bottom of the pogo stick, bent and flexed at the joints, just as a real foot would if a person were hopping up and down.

Singer was attending the 14th annual meeting and scientific symposium of the American Academy of Orthotists and Prosthetists, a six-day conference for makers of orthopedic braces and artificial limbs.

Those at the conference are a long way from helping physicians create bionic men and women with super-human powers, they stress. But new, space-age materials and a better understanding of human physiology have allowed them to do things that only a few years ago were just dreams.

One researcher Friday was showing off a $30,000 artificial arm that operates on electrical impulses produced by muscle contractions. It is so sophisticated that it allows a user to hold an eggshell in its lifelike fingers or grip up to 20 pounds a few seconds later.

At another booth, an exhibitor demonstrated a leg with a hydraulic device inside that allows a person to walk up or down inclines with ease. Another booth had leg braces so light that they could be balanced on the fingertips.

The plastic artificial foot, when attached to an artificial leg, puts the bounce back in a user’s walk and allows him or her a natural gait.

That may seem like minor developments to those with both arms and both legs. But to the estimated 413,000 amputees in the United States and those who try to return them to normal lives, they are major victories, said Albert Rappoport, a certified prosthetist based in Seattle.

Rappoport, who lost a leg in an accident in 1979 at age 16, said he was fitted with a foot made of wood and foam. When he tried to run, “it felt like a board. All the impact would translate through shock waves” from his foot up to his thigh.

That ended only when he bought one of the newer feet first marketed in 1984, said Rappoport, who skis, plays tennis and runs. The foot is referred to as “energy conserving” because implanted devices made of plastic or other material translate the impact of a step into a thrust forward and saves the wearer effort as well as pain.

John W. Michael, director of the department of prosthetics and orthotics at Duke University Medical Center in North Carolina, said almost all the newest advances involve the conservation of human energy through implanted devices or lighter weight.

“Forty years ago, the major materials were wood and leather” for prostheses, said Michael. Today, he said, prosthetists are using such things as laminated plastics, carbon fibers and acrylic resins. The new materials have led to what Michael described as “an explosion of new concepts.”