MUCH of modern medicine is high-tech wizardry. Broken bones, however, are still dealt with in a clumsy, old-fashioned way that frequently involves screws, nails and pins. Even the simplest operation can result in infections and incomplete healing if those devices are not placed as they should be. In dramatic circumstances-for instance on a battlefield, where surgeons cannot use X-ray machines and there is no proper operating theatre-the need for so many bits and bobs can make effective surgery impossible. Thousands of soldiers fighting in Iraq and Afghanistan, for example, have had limbs amputated after injuries that could have been treated at any hospital.
It was with them in mind that DARPA, the research-funding agency of America's Department of Defense, approached a group of scientists at the University of Texas, Houston, two years ago. DARPA wanted something that army doctors could carry in their bags and use to mend injured limbs on the spot, before amputation became inevitable. The researchers, led by Mauro Ferrari and Ennio Tasciotti (who have since moved to the Methodist Hospital Research Institute in the same city) came up with an idea that could change orthopaedic surgery once and for all: a material that surgeons can implant or even inject; which fixes a fractured bone quickly; and which then leads to its full regeneration, with no need for nails and pins.
The material in question, the product of a collaboration between biologists, nanoengineers and mathematicians, is based on a chemical called polypropylene fumarate. It is activated at 37℃, the temperature of the human body. When applied to a broken bone it solidifies and works like a glue, bringing the two parts of the fracture together. That is necessary, as any orthopaedic surgeon knows, because if a gap of more than a few millimetres is left between fragments the bone will never heal.