Fracture Healing

There are two type of healing :1. Healing by calus (natural)2. Healing by direct union

Healing by Calus

1. Tissue destruction and haematoma formation

2. Inflamation and cellular proliferation3. Callus formation4. Consolidation5. Remodelling

Hematoma Formation (1st)

• Vessel are torn • Hematoma forms in medullary canal and

surrounding soft tissue • Bone at the fracture surface deprived of a

blood supply, dies back for a millimeter or two

Hematoma Form. continues

• Dead bone and tissue = inflammatory reaction including vasodilation, plasma exudate, and inflammatory cells

Inflamation and cellular proliferation (2rd)

• First 8 hours (acute inflamation) proliferation and differentiation of mesenchymal stem cells the fragment ends surrounded by cellular tissue creates a scaffold across the fracture site by cytokines and growth factor

Cellular Formation Phase(2nd)

Acidic environment but turning neutral

Callus Formation Phase (3rd)

• Fibroblast deposit collagen in the granulation tissue

• Stem cell provide chondrogenic and osteogenic cell

• Soft Callus is formed (woven bone) about 4 weeks the become “unites”

• Osteoclast (derived from new blood vesels) act to mop up dead bone.

• Internal callus (grows quickly to create rigid immobilization)

Callus Phase continued

• Hard callus – a gradual connection of bone filament to the woven bone that becomes more densely mineralized (Acts like a temporary splint)

• Bone is beginning to strengthen and immobilize

• If proper immobilization does not occur; cartilage will form instead of bone

Consolidation Phase (4th)

• Woven bone Lamellar bone (3-4 months)• Bone ends become crossed with a new

Haversian system that will eventually lead to the laying down of primary bone

• Osteoblasts fill in the remaining gaps between the fragments with new bone

• Fracture is bridged and united

Remodeling Phase (5th)

• Remodeling hard callus to compact/solid bone • May take a few years • Completed when the fractured bone has been

restored to its original form or shape or when it can withstand the imposed stresses placed on it

Conditions that interfere with fracture healing

• Poor blood supply to the fractured area; could lead to avascular or aseptic necrosis

• Poor immobilization of fracture site may cause misalignment or deformity

• Infection – more common with open fractures