New Material Could "Revolutionize" Treatment Of Broken Bones

Washington D.C., August 24 -- A new material that could speed the healing of severely fractured bones and reduce the need for invasive surgery was described here today at the 220th national meeting of the American Chemical Society, the world's largest scientific society.

The material - a polymer with the consistency of putty - could replace the cements and metal devices now used internally to hold broken bones together, says the study's principal researcher Amy Burkoth, a graduate student at the University of Colorado at Boulder. She carried out her research under the guidance of Kristi Anseth, Ph.D., a professor of chemical engineering at the university.

The polymer could "revolutionize" the way bone injuries are treated, Burkoth says.

Currently, an external cast is used to hold broken bones in place. To treat more serious fractures, metal pins, plates and screws are surgically inserted inside the body. But these devices "shield the injured bone and prevent complete healing, and often require a second surgery for removal," says Burkoth. Ideally, a material would have the strength of metal and serve as a temporary scaffold that dissolves as the bone heals, she says.

The biodegradable materials now in use fall far short of this ideal. Over time they soften, deteriorating into gelatinous globs that lack the strength needed to hold fractured bones together.

The new polymer dissolves from the surface inward, so it retains its strength much longer. Moreover, it can be tailored to degrade over a period of several days to more than a year, depending on the type of injury.

"The material is designed to degrade like a bar of soap," says Burkoth, "and we can tailor the degradation rate so it can exactly match the bone's healing rate. This allows for a gradual transfer of the load from the degrading polymer to the healing bone."

Another advantage of the polymer is that it can be molded right on the bone defect, which makes it easier for surgeons to use. To harden it in place, an intense light is applied, causing cross-links between individual molecules to form and stiffen the polymer.

Burkoth cautions that some problems still must be resolved. For example, when the polymer is applied thickly, the light may harden the surface but not the interior all the way through. To address this, the group is testing the use of light in conjunction with other types of reactions.

The paper on this research, PMSE 288, will be presented at 11:15 a.m., Thursday, Aug. 24, at the J.W. Marriott Hotel, Grand Ballroom, Salon III.

Amy Burkoth is a graduate student at the University of Colorado at Boulder.

A nonprofit organization with a membership of 161,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.