Wolff's Law

The spine is used as an example of bone growth under axial load despite separation by intervertebral discs. Wolff's law states that healthy bone adapts to the loads placed on it. Increased loading in a bone region can lead the body to lay down additional bone there. Bone adaptation does not require direct contact between two bones. Loading can stimulate bone adaptation in people with low bone density or osteoporosis risk without requiring direct bone contact.