SPONTANEOUS STRAIGHTENING: After a fracture, blood rushes to the site of injury, forming a hematoma (1). Next to form is the soft callus (purple), flexible tissue containing osteoblasts, chondrocytes, and other types of cells that surrounds the bone fragments (2). A bidirectional growth plate on the concave side of the fracture promotes bone growth (orange) in opposing directions, generating a force that brings the bone fragments into alignment (3). The soft callus ossifies into solid bone (4). © 2014, LISA CLARK. ADAPTED FROM FIGURE 7, ROT ET AL.
The paper
C. Rot et al., “A mechanical jack-like mechanism drives spontaneous fracture healing in neonatal mice,” Dev Cell, 31:159-70, 2014.
When people break a bone, they usually go to an orthopedist to straighten out any misaligned pieces so that the bone does not heal crookedly. But doctors have long observed that when infants get fractures—even if they receive minimal medical intervention—their bones heal reasonably straight.
The assumption had been that fractures in infants at first heal crookedly and then are reshaped through bone remodeling, a lifelong process by which old or damaged bone is resorbed and replaced. But researchers at the Weizmann Institute of Science in Rehovot, Israel, showed that mouse bone fragments realign themselves before fusing back together.
To better understand the healing ...
