How do bones remodel in response to mechanical load?

• A. Osteocytes detect strain; osteoclasts resorb bone on loaded surfaces.
• B. Osteocytes detect strain; osteoblasts are stimulated on loaded surfaces to add bone; resorption occurs on unloaded surfaces.
• C. Only osteoclasts remodel bone.
• D. Remodeling occurs only during growth.

Answer: (B)

Osteocytes sensing strain coordinate bone remodeling by directing where new bone should be formed and where it should be removed. When a bone surface experiences higher mechanical load, osteocytes detect the increased strain and send signals that stimulate osteoblasts on that surface to lay down new bone, strengthening the area. In contrast, surfaces that are not loaded receive signals that favor resorption by osteoclasts, removing bone where it’s less needed. This coupled process—formation on loaded areas and resorption on unloaded areas—lets bone adapt its density and architecture to habitual forces, aligning with Wolff’s law.