The agency's RFP asks for a dynamic substance which, when packed in and around a compound bone fracture, provides full load-bearing capabilities within hours.
Darpa, the Defense Advanced Research Projects Agency, wants help developing "fracture putty," a substance that it hopes will be able to make broken limbs functional again in a matter of hours.
"DARPA seeks to develop a dynamic putty which, when packed in/around a compound bone fracture, provides full load-bearing capabilities within hours, creates an osteoconductive bone-like internal structure, and degrades over time to harmless resorbable by-products as normal bone regenerates," the agency said in its request for proposals (RFP).
According to Darpa, about 30% of battlefield trauma cases involve bone fractures. Injuries sustained as a result of battlefield action may be severe, with bones pulverized by the massive force of modern munitions. Soldiers injured thus face significant loss of bone and tissue mass, making reconstruction and recuperation difficult.
"Amputations have become increasingly common," Darpa's RFP states. "Current treatment modalities, such as internal or external fixation with Ti[tanium] plates, screws, and rods, and the Ilizarov distraction method for bone-lengthening, have significant deficiencies, arising from the severe mechanical property mismatch between Ti and bone."
Fitting issues further complicate fractures and raise the risk of infection, and current bone-setting technology leaves those treated facing long recovery periods.
"More effective methods for treatment of skeletal trauma are urgently needed," says Darpa.
Darpa's goal is "put it in, close it up, good to go."
To achieve that end, the agency acknowledges that it needs breakthroughs in technology. "Fracture putty" needs to bond with bone but not soft tissue. It needs to harden inside the patient's body and to degrade harmlessly over time. It needs to be able to adapt to biochemical signals, like real bone.
"Fracture Putty represents the ultimate convergence of materials science, mechanics, and orthopedics," Darpa program manager Mitchell Zakin said in a statement. "We want to hear from potential performers with expertise in chemistry, biomaterials, adhesives, mechanics, theoretical modeling of dynamic systems under complex mechanical stress, biology of bone, animal models of bone trauma, clinical orthopedics and orthopedic surgery, and engineering."