2. Outline of the preasentation
• Introduction
• Bone healing
• Types of bone healing
• Factors affecting bone healing
3. Introduction
•Fracture could be caused by-Injury
-reapetitive stress
-Abnormal weakening of abone
•Bone injuries result from application of forces that exceed the
strength of skleton
4. • Bone healing requires the recruitment of appropriate cells and
expressions of genes at right time.
• Clinical union-progressive increase in stiffness and strength that
makes the fracture site stable and pain free.
• Radiological union-plain radiograph shows bone trabeclea crossing
the fracture site
6. Bone healing by callus formation
•Steps
1.Tissue destruction and hematoma formation
-vesels are torn away and hematoma is formed around the
fracture site
7. 2.Inflamation and cellular proliferation
-with in 8 hrs
-inflammatory cells arrive
-Mesenchymal stem cells from periostium and surrounding
Muscle breach medullary canal and prolifrate
8. 3.callus formation
-the stem cells provide chondrogerm and oesteogerm cells
-cellular mass,cartilage and immature bone form a callus
-the woven bone is continuously mineralized-finally fracture
Unites at about 4 weeks
9. 4.consolidation
-the woven bone is transformed to lamellar bone with
continuous activity of osteoblast and osteoclast
-slow process ,may take months
11. Healing by direct union
• No stimulus for callus formation
• Fracture surfaces are laid down by new capillaries and
osteoprogenator cells growing in from the edges
• The implant diverts the stress away from the bone
• Healing is slower
• Two types-Gap healing
-Contact healing
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• Gap Healing-there is intermidiate woven bone formation
• Contact healing-whre there is no gap, lamelar bone is laid down
directly with no intermediate woven bone
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• Einhorn described 4 destinict responses to fracture depending on the
location-soft tissue
-periostium
-cortex
- bone marrow
• the most important being periostium-commited ostioproginator and
uncomited mesenchymal cells are released.Inhanced by movement
and inhibited by regidity.The same is true for soft tisssue
19. Injury variables
•1 Open fractures
-can cause soft tissue disruption ,fracture dsplacement even bone
loss.
- Extensive soft tissue injury dysrupts blood supply to fracture site
causing prevention of hematoma formation repair tissue
20. 2.Severity of injury
-high energy injuries causes comminuted fractures and soft tissue
injury causing decrease blood supply to fracture site
-extensive injuries cause increase volume of necrotic tissue and
impedes mesenchymal cells invasion.
3.Intra articular fractures
-are unstable fractures-delayed healing or non union may
occure
4.Segmental fracures-decrease intramedullary and periosteal blood
supply to the middle fragment causing delayed or malunion.
22. Patient variables
1.Age
-infants have rapid fracture healing
-rate of fracture healing is inversely proportional to age till skeletal
maturity
2.Nutrition
-for cell migration, proliferation, matrix synthesis greater energy
is required
-Healing is better in well nourished than severely malnourished
23. 3.Systemic hormones
-Corticosteroids-may compromise healing by inhibiting
diferentietion of osteoblasts from mesanchymal
cells and decreasing production of matrix
-Thyroid hormones,calcitonin,insulin-inhance fracture healing
-Diabetis and rickets –retard fracture healing
-Nicotine products(cigarette smoking)-inhibit fracture
healing
24. Tissue variables
1.Form of bone
-Healing in cancelous bone is faster than cortical bone due to
high surface area to unite volume ratio
2.Bone necrosis
-
-Necrosis at one or two sides of fracture fragment
decreases bone healing
30. Union and Consolidation
Union
•Is incomplete repair
•Callus is calcified
•Fracture site is tender
•Fracture lining is still present on x-ray
•Attempt to angulate is painful
•Subject should be protected
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Biological causes of delayed union
-Inadeqate blood suply
.desplaced fractures or comunited fractures lead totearing of
periostial and intramedulary vesels causing necrosis of fracture
ends
-Soft tissue injury
.eliminates osteogenic cells inpute
-periostial stripling
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Biomechanical causes of delayed union
-Improper splintage-excessive traction or excessive movement
-Over rigid fixation
-infection-causing bone lysis,necrisis,puss formation,implant loosening
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Treatment
I .Conservative
-Eliminate any cause of delayed union
-Promote healing by creating aproprate environment
.Muscular excercise
.Weight bearing in cast or brace
II.operative
-if union is delayed for more than 6 months
-internal fixation and bone grafting
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None union
• can be diagnosed when a
minimum of 9 months elapsed
since fracturewith no
progressive healing for 3
months
• Fracture is visble on x-ray
• bone ends shows either
exuberant callus or atrophy
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Biological and patient related causes
• Poor soft tissue
• local infections
• associated drug abuse- anti
inflamatory,imuno supressers
• poor compliance
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Malunion
• diagnosed when fracture joins in
unacceptable
angulation,rotation,
shortening
Causes
-failure to reduce or stablize
fracture adequatly
-gradual collapse of
communited or fractured
osteoporetic bone
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→In children angular deformity near,especialy near a joint remodels
throuhh time but rotational
→Malalighment >15 degrees may cause assymetrical loading of joints
and this may cause pathologis like secondary osteoarthritis
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Electromagnetic and ultrasound stimulants
• EM increases bone morphogenic
proteins and has been used
since 1970s for rx of delayed
union and non union
• Ryaby et al Osteoblasts when
exposed to EM fields,release
many growth factors which are
necessary for bone healing
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-Low Intensity Ultrasound
• Has been shawn to increase calcium absorption to caltures of
cartilage and bone
• The mechanism is not known
• It has been shawn to inhance fracture healing in patients with
DM,vascular insuficiency,osteoporesis and patients taking NSAIDs
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Growth factors
• Because groth factors like TGF,PDGF,BMP,FDGF...which are found
in matrix play important role in fracture healing,it is tought it
stimulates healing if it is given for patients.
• John et al used human recobinant BMP for the treatment of non
union and delayed union-had success rate of 93%-100%.
