Which principle describes bone remodeling in response to loading?

• A. Darcy's Law
• B. Bernoulli's Principle
• C. Wolff's Law
• D. Avogadro's Law

Answer: (C)

Wolff's Law states that bone adapts its density and structure in response to mechanical loading. When a bone experiences regular stress, osteocytes sense the strain and signal osteoblasts to form bone in the areas under load, increasing mass and aligning internal trabeculae with the principal directions of stress. If loading decreases, remodeling shifts toward resorption, weakening bone in under-stressed regions. This mechanism explains why athletes’ weight-bearing bones become stronger and why immobilization or spaceflight lead to bone loss—bone remodels to optimize strength for the forces it actually encounters. The other options describe different physical phenomena—fluid flow through porous media, fluid pressure changes with speed, and gas law relationships—not bone remodeling.