Memory metal 'helps bones heal'

New alloy could help breaks heal faster

A metal alloy that can "remember its shape" could improve the treatment of badly broken bones, say researchers.

When doctors reconstruct shattered legs and arms, they normally use stainless steel wire to hold bones together.

But the stainless steel does not always hold its shape, which means that the bones may move out of place and heal badly.

However, researchers at Ohio State University say Nitinol - a nickel and titanium alloy - has the potential help broken bones heal faster.

Used in the place of stainless steel the researchers found Nitinol held in position far better.

The trick is to cool the Nitinol, then stretch it before wrapping it around the damaged bone section.

Six week healing process

When it heats up again, it tries to return to its original shape, and exerts a constant pressure while doing so - pushing pieces of broken bone together.

In the research, the team used cylindrical tubes to represent bones, which could move to represent what would happen during a six-week fracture-healing period.

The stainless steel wire, in comparison, was unable to cope with the movement of the bone, and quickly stopping compressing them.

Using the alloy could, in theory, allow far quicker healing times.

Alan Litsky, an associate professor of orthopaedics and biomedical engineering, said: "Stainless steel will hold thing where they were, while Nitinol will push the pieces of a broken bone together.

"If you use a stainless steel wire and something loosens, the compression on the fracture is lost."