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🦴 How does a broken bone heal?

A broken wrist looks like a pencil line on the film. Follow the living construction site from clot and inflammation through soft callus, woven bone, and months of remodelling.

5
lessons
~20 min
to learn
🔬 Science
subject
Adults
level
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What you’ll learn

  1. The break becomes a repair siteExplain how vessel damage, haematoma, inflammation, and mechanical protection start fracture healing.A break becomes a clot-filled, signal-rich repair site before a visible callus forms.
  2. Soft callus buys timeDescribe how fibrous tissue and cartilage make a flexible provisional bridge.The soft callus restores continuity while blood vessels and repair cells prepare mineralised tissue.
  3. Mineral makes a hard callusTrace the replacement of soft callus with mineralised woven bone.Vascular invasion and osteoblast activity turn the flexible bridge into a stiffer hard callus.
  4. Remodelling takes monthsExplain coupled osteoclast and osteoblast activity and the influence of loading and age.Remodelling removes excess woven bone and rebuilds organised lamellar structure over months to years.
  5. The whole sequenceIntegrate the overlapping stages into a complete explanation of fracture healing.Haematoma, soft callus, hard callus, and remodelling are successive dominant phases of one living repair process.

Questions this course answers

What forms first at the fracture site?

Bleeding from damaged vessels produces a clot or haematoma that starts the inflammatory and repair sequence.

Put the main secondary-healing materials in order.

The repair moves from clot, to flexible scaffold, to mineralised woven bridge, to organised mature bone.

Which cells lay down new bone matrix during hard-callus formation?

Osteoblasts secrete osteoid and support mineral deposition; osteoclasts mainly resorb tissue during reshaping.

Match each stage to its dominant description.

Each label names the material or activity that dominates at that point, although the phases overlap.

How does a broken bone heal?

The phases overlap. Alignment, stability, blood supply, age, health, and fracture type influence the pace and outcome. Very rigid contact can instead heal with little callus.

Grounded in trusted sources

  • Sheen JR, Mabrouk A, Garla VV. Fracture Healing Overview. StatPearls. Updated 2023 Apr 8. https://www.ncbi.nlm.nih.gov/books/NBK551678/
  • Schell H, Duda GN, Peters A, Tsitsilonis S, Johnson KA, Schmidt-Bleek K. The haematoma and its role in bone healing. J Exp Orthop. 2017;4:5. https://pmc.ncbi.nlm.nih.gov/articles/PMC5296258/
  • Bigham-Sadegh A, Oryan A. Basic concepts regarding fracture healing and the current options and future directions in managing bone fractures. Int Wound J. 2015;12(3):238-247. https://pmc.ncbi.nlm.nih.gov/articles/PMC7950494/
  • Gamble JG. Pediatric Fracture Remodeling: From Wolff to Wnt. Cureus. 2025;17(1):e78266. https://pmc.ncbi.nlm.nih.gov/articles/PMC11782688/
  • Casanova M, Schindeler A, Little D, Muller R, Schneider P. Quantitative phenotyping of bone fracture repair: a review. Bonekey Rep. 2014;3:550. https://pmc.ncbi.nlm.nih.gov/articles/PMC4119206/

Every Wunder lesson is built from real, reputable sources — never invented.

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