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1. FRACTURE HEALING

2. BONE COMPOSITION
 Cells
 Osteocytes
 Osteoblasts
 Osteoclasts
 Extracellular Matrix
 Organic (35%)
Collagen (type I) 90%
 Inorganic (65%)
Primarily hydroxyapatite Ca5(PO4)3(OH)2

4. TYPES OF BONE
 Lamellar Bone
 Collagen fibers arranged in parallel layers
 Normal adult bone
 Woven Bone (non-lamellar)
 Randomly oriented collagen fibers
 Seen in sites of rapid bone formation, eg: fetal
skeleton,
 In adults, seen at sites of fracture healing,
tendon or ligament attachment and in
pathological conditions

5. BONE FRACTURES AND HEALING

6. BONE FRACTURES
 Break in the continuity of bone
 Traumatic/ non traumatic
 Complete/ incomplete
 Types:
 Closed (simple)- overlying skin is intact
 Compound- fracture site communicates with the
skin surface
 Displaced: when the ends of bones at fracture site
are not aligned
 Pathological fracture: if the break occurs in bone
altered by disease process

7. FRACTURE HEALING
1Day - Hematoma formation (fibrin mesh)
3Day - Inflammation – PDGF, IL, TGF
1Week - Soft callus – granulation, matrix.
3-6Weeks - Callus – ossification, woven bone
8+Weeks - Re-modeling – absorb/deposit, strength,
lamellate

8. FORMATION OF HEMATOMA
 Tissue disruption results in rupture of blood
vessels and hematoma formation at the
fracture site.
 Hematoma fills the gap and surrounds the
area of bone injury.
 Clotted blood provides a fibrin mesh and
seals off the fracture site.
 Influx of inflammatory cells and ingrowth of
fibroblasts and new capillary vessels.

9. FORMATION OF SOFT CALLUS
 Factors (eg PDGF, IL), produced by degranulated
platelets and inflammatory cells activate
osteoprogenitor stem cells in periosteum, medullary
cavity and surrounding soft tissues and stimulate
osteoblastic and osteoclastic activity.
 Activated mesenchymal cells in the soft tissue and
bone surrounding fracture line differentiate into
chondroblasts, that make fibrocartilage and hyaline
cartilage
 Thus Soft callus or procallus is formed, which are
uncalcified and fusiform tissue, by the end of first
week.
 Provides some anchorage between ends of fractured
bones.
 Do not offer structural rigidity for weight bearing.

11. FORMATION OF CALLUS
 Activated osteoprogenitor cells deposit subperiosteal
trabeculae of woven bone, oriented perpendicular to
cortical axis and within medullary cavity.
 Newly formed cartilage undergoes enchondral
ossification forming a network of bone that connects
to subperiosteal trabeculae of woven bone
 Thus fractured ends are bridged by bony callus.

12. REMODELLING
 Woven bone is gradually converted to
lamellar bone.
 Medullary cavity is reconstituted.
 Bone is restructured in response to stress
and strain, removing excess of callus.

14. COMPLICATIONS
 Delayed union
 Non union
 Malunion
 Bone necrosis – nutrient artery
 Pseudoarthrosis- false joint

15. PREREQUISITES FOR FRACTURE HEALING
 Adequate blood supply
 Adequate mechanical stability

16. FACTORS AFFECTING HEALING
 Immobilization
 Improper reduction – abnormal position
 Infection, debris, dead tissue in wound
 Tobacoo and alcohol abuse
 Nutrient deficiency states: calcium, Vitamin D,
proteins
 Corticosteroids and prolonged NSAIDS use