Summer 2008

Magnets to Correct Sunken Chest

Michael Harrison, M.D.

Pediatric surgeon Michael Harrison, M.D., is conducting a trial to test whether magnets can effectively correct the chest deformity pectus excavatum, or sunken chest.

Sunken chest is a congenital abnormality that causes the cartilage that connects the ribs to the sternum to pull the sternum inward. The most common congenital chest deformity, it occurs in about one in 800 children born in the United States each year, and is three times more common in boys than girls.

Nationwide, there are roughly 4,000 patients per year who are candidates for treatment, but, Harrison explains, only about half of them undergo surgery because the available procedures are severe and the condition itself is not life-threatening.

"The real issue is the procedure to have this corrected is agonizing," says Harrison, who has 25 years of experience performing these major surgeries. "A better strategy is to make the correction as an orthodontist moves your teeth, by applying pressure gradually over time. So there is no brutal operation, no pain and no risk."

The new procedure, called the Magnetic Mini-Mover Procedure, or 3MP, involves riveting a powerful earth magnet onto the child's sternum. The magnet is encased in a titanium capsule to ensure safety. The surgery can be done during an outpatient visit and the child goes home on the same day with relatively little discomfort.

A second magnet is embedded into a custom-shaped plastic brace, about the size of a dinner plate, worn directly on the chest, to gradually pull the sternum outward. There are no straps; the attraction between the two magnets holds the brace in place.

The brace has two distinct properties. To make the process pain-free, the magnetic force is adjustable, and the patient can increase or decrease the pull on the sternum at any given time. There is also a data logger on the device, enabling Harrison to see how many hours and at how much pressure the child is wearing the brace.

"When they come into the office, we plug in the device and see a month's worth of data, and it is graphed. This allows us to analyze the science and figure out how hard it needs to pull, and for how long, to move x amount of inches," says Harrison. "The best part is that the readout is also a compliance monitor."

Currently, there are four patients in the trial, and Harrison will test a total of 10 patients, aged 8 to 14, by the end of the year. One of the main questions Harrison hopes to answer is the length of time the child has to wear the brace. At this point, he estimates three to 12 months, depending on the severity of the deformity.

"The patients are all doing remarkably well," says Harrison. "One patient wears his brace 90 percent of the time and his deformity is visibly improving in a matter of months."

This procedure marks one of the first times that magnets have been embedded inside the body to treat a health condition. Harrison hopes that it will be offered nationwide as an alternative to major surgery, as well as serve as a model technique for other medical interventions, such as scoliosis.

The trial is being funded by a grant from the Office of Orphan Products Development of the FDA.

For more information, contact the UCSF Division of Pediatric Surgery at (415) 476-2538.

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