fracture healing and its stages

1. Fracture healing
Dr Kushal Shah

2. History
• In 17th century Albrecht Haller, observed invading capillary buds in fracture
callus and thought that blood vessels are responsible for callus formation
• John Hunter, a pupil of Haller, described the morphologic sequence of
fracture healing.
• In 1873, Kolliker observed the role of multinucleated giant cells, osteoclast
to be responsible for bone resorption.
• In1939, Gluksman suggested pressure and shearing stresses are possible
stimuli for fracture healing.
• In 1961, Tonna and Cronkie demonstrated the role of local mesenchymal
cells in fracture repair.

3. Healing word- misnomer
• Healing means to make whole or sound again, to cure, leaving a scar
behind. But following fracture a scar is not formed, instead a bone
has formed a new at the original fracture site. So rather than bone
healing the appropriate nomenclature would be BONE
REGENERATION

4. What is bone ?
• Bone is essentially a highly vascular, living, constantly changing
mineralized connective tissue which makes up body’s skeleton.
• Other functions are: - Bone provides protection for the vital organs of
the body( eg: heart and brain) - The hematopoietic bone marrow is
protected by the surrounding bony tissue. - Storage of calcium and
phosphate.

5. BONE COMPOSITION
Cell
• OSTEO PROGENITOR CELLS
• 2. OSTEOBLASTS
• 3. OSTEOCLASTS
• 4. OSTEOCYTES
• 5. BONE LINING CELLS
ECM
• ORGANIC & WATER 35%
• Type Ι Collagen 90%
• Osteocalcin,
• Osteonectin,
• Proteoglycans,
Glycosaminoglycans,
• Lipids (ground substance)
• 2. INORGANIC 65% Primarily
hydroxyapatite Ca10(PO4 )6
(OH)2

6. Mechanism of bone formation
A. Cutting Cones
• B. Intramembranous Bone Formation
• C. Endochondral Bone Formation

7. Cutting cone
• Primarily a mechanism to
remodel bone
• Osteoclasts at the front of the
cutting cone remove bone
• Trailing osteoblasts lay down
new bone

8. Intramembraneous Bone Formation
• Mechanism by which a long
bone grows in width.
• Osteoblasts differentiate
directly from pre osteoblasts
and lay down seams of osteoid.
• Does NOT involve cartilage
anlage.
• It mainly forms cancellous
bone.

9. ENDOCHONDRAL BONE FORMATION
• Mechanism by which a long bone
grows in length
• Osteoblasts line a cartilage
precursor
• The chondrocytes hypertrophy,
degenerate and calcify (area of low
oxygen tension)
• Vascular invasion of the cartilage
occurs followed by ossification
(increasing oxygen tension)

11. Direct Healing
• CONTACT HEALING: When there is direct
contact between the cortical bone ends,
lamellar bone forms directly across the
fracture line , parallel to long axis of the bone,
by direct extension of osteons.
• GAP HEALING: Osteoblasts differentiate and
start depositing osteoids on the exposed
surfaces of fragment ends, mostly without a
preceding osteoclastic resorption which is
later converted into the lamellar bone .

12. Type of bone healing

13. Indirect bone healing
• Mechanism for healing in fractures that have some motion, but not
enough to disrupt the healing process.
• Bridging periosteal (soft) callus and medullary (hard) callus re-
establish structural continuity
• Callus subsequently undergoes endochondral ossification
• Process fairly rapid - weeks

14. Stages of fracture repair
• In 1975, Cruess and Dumont proposed that fracture healing may be
considered to consist of three overlapping phases: an inflammatory
phase, a reparative phase, and a remodeling phase
• In 1989, FROST proposed the stages of fracture healing five stages.
• 1- stage of haematoma
• 2- stage of granulation tissue
• 3- stage of callus
• 4- stage of modelling
• 5- stage of remodelling

15. Duration
• The inflammatory phase peaks
within 48 hours and is quite
diminished by 1 week after fracture.
• The reparative phase becomes
activated within the first few days
after fracture and persists for 2-3
months.
• The remodelling phase lasts for
many years