March 1, 2008 Biomedical engineering principles helped an inventor create a boot that fits over a supportive cast, making it easier to walk without crutches. The device spreads the load over a larger area to reduce the stress put on the foot. Research has found that walking on an injured limb speeds the healing process by encouraging blood flow and muscle movement.
Maybe you've been there -- a sports injury, a car accident or a mishap at home. Next thing you know, your broken or fractured bones are wrapped in a cast for weeks. Now, a retired firefighter has invented a new type of cast that helps the injured ditch their crutches for short stints so they can get up and go.
Four years ago, Bob Bentivegna needed a cast to allow a fractured ankle bone to heal. A day later, Bentivegna begged his doctor to cut the cast off. He said it was impossible to get around.
"I had no relationship with those crutches. I made up my mind I wasn't going to walk around on them for six weeks … couldn't," says Bentivegna.
So Bentivegna began looking for a way to bear weight on his cast. In his basement workshop, he removed the padded headrest from exercise equipment, and attached four bungee cords to it. He anchored the contraption to his leg using a vaccuum cleaner belt. That's how he walked around for six weeks.
"When I was re-MRI'ed they discovered that there was no disunion. The ankle had actually healed," says Bentivegna. That's when he launched the idea for what he calls the "cast skate" -- a lightweight appliance that attaches to a plaster or fiberglass cast. The cast skate absorbs impact, distributes weight, and protects the cast from wear and tear.
The cast skate attaches to the leg with adjustable straps, giving it the appearance of a skate -- without the wheels. The wearer then inflates a foam insert in the sole of the cast skate, stabilizing it.
Podiatrist Dr. Gregory Parker has had patients grumble when he hands them crutches. He likes the theory behind the cast skate.
"Essentially, if you put your foot into a big pillow and plant it on the ground, it's gonna disperse the weight evenly. That's what this looks like it aims to do," says Gregory Parker, D.P.M., from Langhorne, Pa.
Biomedical engineering, born out of necessity, may soon help patients get around easier. Bentivegna says the cast skate has been issued a patent and he is currently talking to manufacturers willing to produce it.
ABOUT FRACTURES: A fractured bone is the same thing as a broken bone. They occur because a bone area is unable to support the energy placed on it. That energy can be acute, as from a car crash or a two-story fall, or chronic and low-energy repetitive activity. The latter is responsible for stress fractures, an overuse injury commonly seen in athletes. The increased demand places on the bone causes it to remodel and become stronger in areas of higher stress, but if the repetitive demands become too great, a stress fracture can result.
HOW BONES HEAL: The 206 bones in the body renew themselves continually through a process known as remodeling, which is also how fractures heal. Complex chemical signals prompt cells called osteoclasts to break down and remove (by absorbing it) old bone. Other cells called osteoblasts deposit new bone. When a bone breaks, inflammatory cells rush to destroy invaders and isolate injured tissue, causing pain, swelling and heat at the breakage site for a few days. Tiny new blood vessels (capillaries) begin growing into the site, and new cells grow, too. New connective tissue bonds fractured bone ends and the remodeling process begins.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.