Bone Healing And Bone Grafting Flashcards
What is the blood supply to the long bones in a mature animal?
Principle nutrient artery
Metaphyseal arteries
Periosteal arteries
What is the blood supply to the long bones in immature animals?
Epiphyseal and metaphyseal arteries
How does blood supply change in a fractured bone?
Develops extraossecous blood supply —- supplying periosteal bone proliferation
What are the stages of indirect healing (aka callus formation)?
Inflammation
Repair
Remodeling
What type of bone healing occurs with unstable mechanical environment/motion between fracture fragments
Indirect
What occurs in the inflammatory stage of indirect bone healing?
From time of fracture, lasting 3-4days
Clot at fracture site
-osteoinductive growth factors causing angiogenesis and bone formation
-abundant mast cells with vasoactive substances
What occurs in the remodeling stage of indirect bone healing?
Takes about 2 months
Clot differentiates into granulation tissue
Gain in strength - soft callus
Mesenchymal cells become osteoblasts
-lay down fibrocartilage
Mineralizes forming a hard callus
-bony union
What is direct bone healing?
Filling of fracture site with no callus
Requires anatomical reduction and rigid fixation which minimize secondary healing phase (usually plate fixation)
Minimal interfragmentary strain
T/F: it take longer to gain mechanical strength when healing has occurred by direct bone healing rather than indirect bone healing
True
Reducing a fracture (increases/decreases) interfragmentary strain
Increases
We try to compensate for this by adding fixators
Gap healing occurs then the fracture gap is _______mm
<1
Interfragmentary strain must be <2%
What is the process of gap healing ?
Osteoblasts deposit lamina bone in fracture gap perpendicular to long axis
Mechanically week at fracture ends
Osteoclasts form cutting cones along osteoblasts to lay longitudinally oriented lamellar bone
Contact healing can only occurs if the defect between fracture sites is ______mm
<0.01
How does contact healing occur?
Lamellar bone is layer in normal axial direction
Bony union and remodeling simultaneous
Initiated by cutting cones of osteoblasts directly followed by osteoblasts
How does healing of cancellous bone occur?
Fracture gap is filled with new trabecular bone followed by the cortical shell
(Eg metaphyseal fractures)