Cancellous bone, also called spongy bone, is one of two types of bone tissues; the other being compact (or cortical) bone. Previously, scientists believed humans “had cancellous bone for the same reasons [humans] use foams in engineering: to absorb energy or make the structure more lightweight,” said principal investigator Christopher Hernandez, Associate Professor of Mechanical and Aerospace Engineering and Biomedical Engineering at Cornell. “But, it turns out that cancellous bone does something different.”
When most objects break, they often lose their mechanical function and fall apart. To avoid breaking, engineers apply surface treatments to car and aircraft parts to harden the surface and keep cracks from starting.
"Cancellous bone does the opposite.” It uses its softer surfaces and a brittle interior to allow the bone to break in a way that actually makes it heal better. The soft surface and brittle interior work together to direct cracks to a less detrimental location. As a result, the bone is able to bounce back" after it breaks.
The finding could help inspire the creation of materials that take advantage of the bone's "function after failure" design, said biomedical engineer Jonathan Matheny.
Cancellous bone is also involved in most osteoporosis-related fractures. Osteoporosis is estimated to affect 200 million women around the world and causes more than 8.9 million fractures a year. The researchers hope the findings could also help scientists identify “people at risk for an osteoporosis-related fracture and prescribe a drug,” Matheny said.
The research was published in the Proceedings of the National Academy of Science (PNAS) on February 29, 2016.
Source: Cornell University press release via EurekAlert!, International Osteoporosis Foundation