Orthopedic surgeons use old technology in new ways

By BOB MASSEY

Feeling Fit Correspondent

How can a device originally created for espionage benefit orthopedic surgeons and their patients?

Welcome to the world of radio-frequency identification (RFID) technology, which recently added orthopedics to one of its many uses.

New Jersey-based orthopedic surgeon Dr. Lee Berger was frustrated when working on patients who had previously received joint implants, such as hip or knee replacements.

In many cases, patients knew little about the type of device they had received, the company that manufactured it, or even the surgeon who had performed the procedure.

Another concern was records of potential recalls or problems with a specific model that a manufacturer might have had. Those details could only be learned through an extensive paper trail, made even more complex when dealing with out-of-state patients.

"What they would do is take an x-ray of the part and try to determine from that which company it came from," said Marlin Mickle, the Nickolas A. DeCecco professor of electrical and computer engineering in the University of Pittsburgh's Swanson School of Engineering. "Then they'd talk to the representative from that particular company, and try to work backwards to look it up in the patient's file to find the information they needed."

But Berger came up with an idea that, if feasible, would save a lot of time and effort -- but had never been done. "Berger first came to me with the idea of putting RFID tags on the implants," Mickle said. "My first reaction was that it's a difficult problem because RFIDs are made to work through air -- not tissue."

The basis for what would become RFID was actually developed in 1945 -- as an espionage tool for the Soviet Union. Similar technology was developed in the United Kingdom and used by allied forces to determine if aircraft were friendly or sent by the enemy.

Modern RFID is a wireless noncontact technology using radio-frequency electromagnetic fields to transfer data from a tag.

The tag is attached to an object, and allows it to be identified and track. The tag contains information that is stored electronically, and can be up to several yards away.

The technology's uses are numerous. For years, RFID tags have been attached to items to prevent shoplifting as well as inventory control. A tag attached to a vehicle can track its progress at it moves along an assembly line. Pets and livestock may have tags injected so the animals can be properly identified.

Mickle was tasked with developing an RFID signal that would pass through tissue. It took about a year.

"If you have an RFID tag, there's no question as to what company the implant belongs to, or what size it is," he said. "You get the information very quickly."

Berger took the successful development a step further.

"Berger formed a company, Ortho-Tag, and we're now in our second year working with them," Mickle said.

Ortho-Tag Inc. represents the growing potential and role of RFID technology in healthcare. The tags have already moved to the next level.

"The question came of what else can we do as long as that's in there?" Mickle explained. "One of the things we can do is put sensors on it."

The sensors can transmit readings such as body temperature, and also pH levels to detect potential infection. Best of all, the tags don't require batteries -- so they never have to be replaced.

"We're now working on other sensors to go with it," Mickle said. "The chip that's there acts as a little server on a network to read all these sensors that are in the area. For tracking, you don't have to inject anything. There's a touch probe that goes on the knee to read everything."