ANATOMY

Unit 4 Notes:Bone Repair

(1) Bone Repair Stages(1) Bone Repair Stages

1- [Instantly] Hematoma Formation

2- [~2-3days] Fibrocartilaginous Callus Formation

3- [~7days] Bony Callus Formation

4- [~6-8weeks] Bone Remodeling

(2) Hematoma Formation(2) Hematoma Formation

1. Bone breaks, blood vessels are torn and hemorrhage.

2. Mass of clotted blood forms at fracture site.

3. Bone cells are deprived of nutrition and die.

4. Tissue at fracture site becomes swollen, painful and inflamed.

(3) Fibrocartilaginous (3) Fibrocartilaginous Callus FormationCallus Formation

1. Capillaries from surrounding vessels grow into the hematoma.

2. Phagocytic cells (Macrophages + Osteoclasts) invade hematoma and clean up debris.

3. Osteoblasts + Osteocytes invade and begin to rebuild bone.

4. Collagen fibers are secreted to connect ends of bone.

(4) Bony Callus (4) Bony Callus FormationFormation

1. Fibrocartilaginous callus develops and hardens to form a bony callus of spongy bone.

2. Bone cells, collagen fibers and chondrocytes (cartilage cells) are continuously secreted to strengthen matrix.

(5) Final Remodeling(5) Final Remodeling

1. Excess material on outside of diaphysis is removed.

2. Compact bone is laid down to reconstruct shaft walls.