Magnets Make Limb Lengthening Easier

Jan 7, 2019

Using magnets and the body's ability to regenerate bone, a University of Cincinnati orthopedic surgeon is taking patients to new heights.

If one leg is longer than the other what are your options? Years ago, the only choice was a painful procedure using an external frame that would stretch the leg, or even amputation. But Dr. John Wyrick is having success with the NuVasive Precice.

This is the titanium rod that is inserted into the leg. Combined with a remote controller, it helps lengthen the limb.
Credit Ann Thompson / WVXU

Precice is one of several "lengthening nails," doctors saw through the bone crosswise and brace it. The body grows new bone in the gap. A titanium rod is placed lengthwise inside the bone. The rod has a magnet-powered motor and the patient has a remote controller with a magnet outside the body that is placed over the rod. Three times a day, three to four minutes at a time, the patient uses the external magnet to lengthen it.

Here is a video of one case NuVasive has on its website.

For Ben Brenner of Loveland, it was a car accident that shattered his femur and damaged his growth plate at age 12. Now decades later with a leg 1-and-5/8-inches shorter, he had severe back pain and was ready to try anything. Dr. Wyrick had just heard about the Precice system using a titanium rod with a magnetic motor.

"I was all about it. He was all for it," Brenner says. "I was his first patient and we worked as a team."

It took just less than a month for Brenner's leg to reach the desired length and he says he "felt a million times better."

There are downsides. Dr. Wyrick says the device is expensive - $15-20,000. It also doesn't work on people who are overweight, because the signal can't reach the bone.

The pain level for Precice doesn't compare to the external fixer, the old technology that screws into a patient's leg. "The different between using the frame and using the nail was night and day," Wyrick says. "The pain level is way down, and in this day and age of opioid problems that has been a huge benefit."

Doctors nationwide also use Precice on cancer patients and patients born with limb defects.