Pliable medical devices could make surgery easier

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Pliable medical devices could make surgery easier

By Amy Norton

NEW YORK, Apr 25 (Reuters Health) - Incredible shrinking and expanding

polymers could one day make the implantation of medical devices far

easier, new lab research suggests.

German and US scientists have developed so-called shape memory

polymers--made of biodegradable materials--that can potentially be

slipped into the body in a compact, " temporary " shape. Once inside, they

can be expanded to fit as needed--forming, for example, " smart sutures "

that close wounds or possibly stents that prop open blood vessels.

According to the researchers, the polymers have the ability to

" memorize " a permanent shape. This means it could become possible to

" scrunch up " sutures, stents or other devices made from the materials,

put them in the body with minimally invasive surgery, then stand back

and let them grow into their permanent shape, one of the study authors

explained in an interview with Reuters Health.

The shrinking and expanding part is temperature-controlled, with a bump

in temperature triggering the polymers to grow back into their original

shape, according to Langer of Massachusetts Institute of

Technology in Cambridge. He and colleague s Lendlein, of

mnemoScience GmbH in Aachen, Germany, found that the concept worked in

rats in which threads of the material were used as sutures to close

surgical wounds.

Their findings were published Thursday in Sciencexpress, the online

edition of the journal Science.

According to the researchers, shape memory polymers could be placed in

the body via laparoscopes, slender tubes that are inserted through small

incisions during minimally invasive surgery. A current challenge in

minimally invasive surgery, they note, is that it is difficult for

surgeons to tie sutures to close an incision.

Shape memory polymers, Langer said, could form " smart sutures that tie

themselves. " In other words, such polymers could be sewn loosely in the

body, then tighten up on their own.

Beyond sutures, the researcher said, these pliable polymers could be

used for screws or glue to be placed in bone--and, potentially, any

device " that's somewhat bulky and might require a major invasive

operation. "

According to Langer, his team's polymers are made of two components

already used in medical devices. " They break down in the body into

harmless elements, so they're safe, " he said.

For implants that need to remain permanent, the materials can be made

non-degradable, Langer noted.

SOURCE: Sciencexpress 2002;10.1126/science.1066102.