6. FRACTURE – DEFINITION AND TYPES
A break in bone or cartilage ,
ranging from a thin crack to a complete break or to many pieces ,
when a bone is impacted by more force and pressure than it can support.
TYPES
CLOSED/SIMPLE
OPEN/COMPOUND PATHOLOGICAL
COMPLETE
INCOMPLETE
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9. CELLS INVOLVED IN FRACTURE HEALING
• MACROPHAGES
• MESENCHYMAL STEM CELLS
• MULTIPOTENT STROMAL CELLS –DEVELOPS INTO OSTEOBLASTS
AND CHHONDROCYTES
• OSTEOBLASTS
• BONE FORMING CELLS
• OSTEOCYTES
• CAPABLE OF BONE DEPOSITION AND RESORPTION
• OSTEOCLASTS
• BREAKS DOWN BONE TISSUE
• MAINTANANCE,REPAIR AND REMODELLING OF BONES
• FIBROBLASTS
• SYNTHESIZE EXTRACELLULAR MATRIX & COLLAGEN - HEALING
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11. FRACTURE HEALING - TYPES
• PRIMARY UNION
• When the ends of a fracture are approximated surgically by
application of compression clamps or metal plates
• Bony union takes place with formation of medullary callus and
without formation of periosteal callus.
• SECONDARY UNION
• More common form of fracture healing when the plaster casts are
applied for immobilisation of fracture.
• Is a continuous process and divided into three stages
• PROCALLUS FORMATION
• OSSEUS CALLUS FORMATION
• REMODELLING
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13. PROCALLUS FORMATION
• HAEMATOMA FORMATION
• BLEEDING AT FRACTURE SITE FROM TORN BLOOD VESSELS
• FIBRIN AND BLOOD CLOT – LOOSE MESHWORK-FRAMEWORK FOR
GRANULATION
• LOCAL INFLAMMATORY RESPONSE
• MACROPHAGES CLEAR MICROBES AND CELLULAR DEBRIS.
• NECROSED BONE SCAVENGED BY OSTEOCLASTS AND MACROPHAGES.
• INGROWTH OF GRANULATION TISSUE
• PROLIFERATION OF MESENCHYMAL CELLS FROM ENDOSTEUM AND
PERIOSTEUM TO FORM A SOFT TISSUE CALLUS
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14. PROCALLUS FORMATION
• CALLUS COMPOSED OF WOVEN BONE AND CARTILAGE.
• CELLS OF INNER LAYER OF PERIOSTEUM HAVE OSTEOGENIC
POTENTIAL AND LAY DOWN COLLAGEN AS WELL AS OSTEOID
MATRIX IN THE GRANULATION TISSUE.
• THE OSTEOID UNDERGOES CALCIFICATION AND IS CALLED AS
WOVEN BONE CALLUS.
• A MUCH WIDER ZONE OVER THE CORTEX ON EITHER SIDE OF
FRACTURED ENDS IS COVERED BY THE WOVEN BONE CALLUS
AND UNITED TO BRIDGE THE GAP BETWEEN THE ENDS, GIVING
SPINDLE-SHAPED OR FUSIFORM APPEARANCE TO THE UNION ,
TEMPORARILY IMMOBILISINGTHE BONE ENDS.
15. OSSEUS CALLUS FORMATION
• The procallus acts as scaffolding on which osseous callus composed of
lamellar bone is formed.
• The woven bone is cleared away by incoming osteoclasts and the
calcified cartilage disintegrates.
• Newly-formed blood vessels and osteoblasts invade, laying down
osteoid which is calcified and lamellar bone is formed by developing
Haversian system concentrically around the blood vessels.
16. REMODELLING
• During the formation of lamellar bone, osteoblastic laying and
osteoclastic removal are taking place remodelling the united bone
ends, which after sometime , is indistinguishable from normal bone.
• The external callus is cleared away, compact bone (cortex)is formed in
place of intermediate callus and the bone marrow cavity develops in
internal callus.
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20. COMPLICATIONS OF FRACTURE HEALING
• Fibrous union may result instead of osseous union if the
immobilisation of fractured bone is not done. Occasionally, a false
joint may develop at the fracture site (pseudo-arthrosis).
• Delayed union may occur from causes of delayed woundhealing in
general such as infection, inadequate blood supply,poor nutrition,
movement and old age.
• Non-union may result if some soft tissue is interposedbetween the
fractured ends.
