1. Unit 5 Notes:
Bone Injury & Repair

2. (1) Bone Injury Increased weight on bone/joint
Irregular movement/manipulation
Twisting
Rotation
Bending

4. (2) Types of Fractures Comminuted Spiral Depressed Transverse Oblique
Open
Compression
Epiphyseal
Greenstick

5. (3) Comminuted Fractures
Bone fragments into 3 or more pieces
Common in aged people, when bones are more brittle

7. (4) Spiral Fractures Ragged break Result of excessive twisting forces
Common sports fracture

9. (5) Depressed Fractures
Portion of broken bone pressed inward
Typical skull fracture

11. (6) Transverse Fractures
Bone breaks straight through bone (perpendicular)
Clean Break

13. (7) Oblique Fractures
Bone breaks on diagonal
Clean break

15. (8) Open Fractures Bone breaks and pierces skin
Common in forearm and shin (leg)

17. (9) Compression Fractures
Bone is crushed
Common in porous bones (due to osteoporosis)
Common in vertebral column

19. (10) Epiphyseal Fractures
Epiphysis separates from diaphysis along epiphyseal plate
Usually occurs where cartilage cells are dying and calcifying

21. (11) Greenstick Fractures
Bone breaks incompletely (like a twig)
Only one side of the shaft breaks, other side bends
Common in children, when bones are more flexible

23. (12) Bone Repair 1- [Instantly] Hematoma Formation
2- [~2-3days] Fibrocartilaginous Callus Formation
3- [~7days] Bony Callus Formation
4- [~6-8weeks] Bone Remodeling

24. (13) Hematoma Formation
Bone breaks, blood vessels are torn and hemorrhage.
Mass of clotted blood forms at fracture site.
Bone cells are deprived of nutrition and die.
Tissue at fracture site becomes swollen, painful and inflamed.

26. (14) Fibrocartilaginous Callus Formation
Capillaries from surrounding vessels grow into the hematoma.
Phagocytic cells (Macrophages + Osteoclasts) invade hematoma and clean up debris.
Osteoblasts + Osteocytes invade and begin to rebuild bone.
Collagen fibers are secreted to connect ends of bone.

28. (15) Bony Callus Formation
Fibrocartilaginous callus develops and hardens to form a bony callus of spongy bone.
Bone cells, collagen fibers and chondrocytes (cartilage cells) are continuously secreted to strengthen matrix.

29. (16) Final Remodeling
Excess material on outside of diaphysis is removed.
Compact bone is laid down to reconstruct shaft walls.