A new study from Rensselaer Polytechnic Institute shows, for the first time, how the little-understood protein osteocalcin plays a significant role in the strength of our bones. A healthy bone is seen on the left. In the case of a slip, trip, or fall, the force of the impact on a bone physically deforms a pair of joined proteins, osteopontin and osteocalcin, and results in the formation of nanoscale holes within the bone's mineral structure, as seen in the middle. These holes, called dilatational bands, function as a natural defense mechanism, and help to prevent further damage to the surrounding bone. However, if the force of the impact is too great--or if the bone is lacking osteopontin, osteocalcin, or both--the bone will crack and fracture, as seen on the right. Findings of the study could lead to new strategies and therapeutics for fighting osteoporosis and lowering the risk of bone fracture.