Sunken chest, which is known medically as pectus excavatum, is a deformity of the cartilage that connects the ribs to the breastbone. The deformed cartilage pulls the breastbone inward, making the chest look caved in or sunken. The condition occurs in about one in 800 children born in the United States each year and is three times more common in boys than girls.
A UCSF team developed the new procedure, in which a magnet attached to the child's breastbone is coupled with a second one outside the chest that creates a steady, controlled, outward pull on the internal magnet to reshape the bone, cartilage and chest wall.
The procedure marks one of the first times magnets have been embedded inside the body to treat a health condition, according to Michael Harrison, MD, professor of surgery and pediatrics emeritus at UCSF and lead investigator of the study.
"We needed to apply a force to gradually remodel the chest wall without piercing the skin," Harrison said. "Magnets do it."
The research team named the new technique the "Magnetic Mini-Mover Procedure," known as 3MP. The 3MP uses a device that includes two parts: a titanium-encased magnet about the size of a quarter that is surgically attached to the child's breastbone and a second magnet embedded in a lightweight plastic brace that the child wears under clothing. The attraction between the two magnets holds the brace in place.
Because the internal magnet is placed just under the skin during an outpatient visit, the child can go home on the day of the procedure with relatively little discomfort. The child wears the brace for three to 12 months, depending on the severity of the deformit y. It can be adjusted to increase or decrease the pull on the breastbone in the same way that orthodontic braces are loosened or tightened.
If successful, the 3MP could revolutionize treatment of pectus excavatum, according to Harrison. Current approaches to correcting sunken chest involve major surgery to open and rebuild the chest and the insertion of metal struts to hold the chest in place while it heals. Complications can occur because the struts are under significant pressure, and the painful recovery can take months.
"The problem with present techniques is that they attempt to reshape the chest wall in one big operation," Harrison said. "A better idea is to apply a little force over a longer time, like the orthodontist moves your teeth."
The use of the magnets has been deemed safe by the U.S. Food and Drug Administration, which has reviewed and approved the 3MP device. The internal magnet is laser-welded in a titanium case, assuring its safety. The magnets have been found to have no effect on the heart or other body parts, and studies have demonstrated that long-term exposure to magnetic fields is not harmful.
Sunken chest had long been considered a cosmetic defect. But recent studies have determined that while not life-threatening, in severe cases the deformity can cause heart and breathing difficulties, because the abnormal breast bone can reduce blood flow to the heart and prevent the lungs from expanding completely, restricting the ability to exercise, according to Harrison. Some patients also suffer serious emotional difficulties and low self-esteem, especially since sunken chest often worsens during adolescence when children are self-conscious about their appearance and seek peer acceptance.
"This is not a trivial problem for these kids," Harrison said. "Most are willing to undergo a big, painful and expensive surgery to fix it. Why not a simple little outpatient procedure to fix it?"
Research ers are seeking potential study participants who have sunken chest and are between 8 and 14 years of age, otherwise healthy and willing to participate in the 12-month-long study of the new procedure.