Metal Detectors Miss Many Surgical Implants, Docs Say

The first study of airport metal detectors since 9/11 has found that artificial hips and knees are almost certain to set off alarms.

But lighter implants, such as plates, screws, nails and wires, often go undetected.

"I was surprised we weren't picking up more of them," said researcher Dr. Edward Rodriguez of Beth Israel Deaconess Medical Center in Boston. "It makes you wonder what else is getting through."

Researchers borrowed a walk-through airport metal detector from a manufacturer.

One hundred twenty-nine volunteers, with a total of 149 metal implants, walked through the detector when it was set at normal sensitivity and high-alert sensitivity.

Every total hip replacement, and 90 percent of total knee replacements, were detected at the normal setting.

But only 14 percent of the plates were detected, and none of the screws, wires or nails. Shoulder and wrist replacements also made it through.

Titanium and cobalt-chromium implants were more likely to be detected than stainless steel implants.

A Transportation Security Administration spokeswoman declined comment on the study, which was published in the Journal of Bone and Joint Surgery.

There were 478,000 knee and 234,000 hip replacements in 2004, and the numbers are growing rapidly as more aging baby boomers suffer arthritis, according to the American Academy of Orthopaedic Surgeons.

Metal implants can weigh a half a pound, said orthopedic surgeon Dr. Scott Rubinstein of the Illinois Bone and Joint Institute.

"The bigger the person, the more the metal," Rubinstein said.

Every time retired Chicago couple Charles and Anna Marie Holzner go through a detector, the alarm goes off. Charles has an artificial hip; Anna Marie has an artificial knee.

They are taken aside by security officers, who pat them down and go over them with a metal-detecting wand.

The Holzners travel frequently to sunny vacation spots where Charles goes scuba diving. The extra security is a hassle, especially when they're running late.

"But if I went through and it didn't go off, it would scare me," Charles said. "I have enough metal in my hip to make two or three guns."

The TSA recommends -- but does not require -- that travelers tell security officers if they have metal implants and where they're located. A traveler who does not want to be patted down in public can request a private screening.

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