Bone remodeling
The continuous cycle of resorption and formation that rebuilds the skeleton throughout life.
Bone is not static. The adult skeleton is continuously dismantled and rebuilt by a coordinated cycle in which osteoclasts resorb a packet of mineralised matrix and osteoblasts refill it. A complete cycle takes months, and roughly ten percent of the skeleton is renewed each year.
This is why bone is the field's reference tissue: it heals by true regeneration rather than scar. A simple fracture, adequately stabilised, is replaced by bone that is essentially indistinguishable from the original — a capacity most tissues lack entirely.
The cycle is tightly coupled. Resorption releases factors stored in the mineralised matrix — including TGF-β and BMPs — which recruit the cells that rebuild. When coupling fails, disease follows: net resorption produces Osteoporosis and bone density. And when a defect is too large for the cycle to bridge, it becomes a critical-size defect.
Related articles
- BoneOsteoblasts and osteoclastsThe two opposing cell types whose balance determines whether bone is built or lost.
- BoneCritical-size bone defectsThe threshold beyond which bone cannot bridge a gap on its own — and the problem most bone engineering exists to solve.
- BoneOsteoporosis and bone densityWhat happens when the remodeling cycle tips toward resorption, and why density is only part of the story.
- FoundationsRepair versus regenerationWhy most human healing produces scar tissue, and what distinguishes it from true regeneration.
- FoundationsThe extracellular matrixThe structural and signaling scaffold cells build around themselves — and the template engineered scaffolds try to imitate.
- BoneBMP-2: bone morphogenetic protein 2The osteoinductive growth factor that moved from a laboratory curiosity to approved clinical use — and the lessons of its dosing.