THE FACTS Just like muscle, human bone grows and strengthens under pressure, and weakens when barely put to use.

This concept  that bone adapts to pressure, or a lack of it  is known as Wolff’s law. It’s the reason astronauts return with reduced bone density after floating in microgravity. And conversely, it explains why studies show that tennis players and fencers develop greater bone mass in their dominant arms and legs.

But this adaptive measure goes only so far. Despite one misconception, there is no evidence that a bone that breaks will heal to be stronger than it was before.

Image Credit... Christoph Niemann

When a bone fractures, it begins the healing process by forming a callus at the fracture site, where calcium is deposited to aid rebuilding, said Dr. Terry D. Amaral, director of pediatric orthopedic surgery at Montefiore Medical Center in the Bronx. In most cases, a plaster cast is applied to protect the fracture site. But because there is no weight or pressure on the limb, it becomes weaker  except at the site of the callus, where calcium is being deposited.