Fracture Healing

1. 
 By Fairuz Khamzah
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Fracture Healing

2. 
 Fracture is a break in the structural continuity
of bone or periosteum.
 The healing of fracture is in many ways similiar
to the healing in soft tissue wounds except that
the end result is mineralised mesenchymal
tissue i.e. BONE.
 Fracture healing starts as soon as bone breaks
and continues modelling for many years.
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INTRODUCTION

3. 
 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.
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WHAT IS BONE ?

4. 
 Living bone is white, with either dense texture like
ivory or honeycombed by large cavites .
 Spongy bone (cancellous) : is composed of a lattice
or network of branching bone spicules or trabeculae.
The spaces between the bone spicules contain bone
marrow.
 Compact bone (cortical / outer): appears as a mass
of bony tissue lacking spaces visible to the unaided
eye.
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MACROSCOPY

5. 5

6. 
 Woven (Immature bone): Characterized by random
arrangement of cells and collagen ,associated with
periods of rapid bone formation, such as in initial
stage of fracture healing.
 Lamellar bone (Mature bone) : Characterized by an
orderly cellular distribution and properly oriented
collagen fibres . This constitutes organised bone both
cortical and cancellous
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MICROSCOPY

7.  Comprises of
osteons (Haversian
systems)
 Osteons
communicate with
medullary cavity by
Volkmann’s canals
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CORTICAL BONE
.

8. HAVERSIAN CANAL
 Haversian canal
Cells, nerves &
vessels
 Volkmann’s
canal
Connects osteons
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osteon
Haversian
canal
osteocyte
Volkmann’s
canal

9. 
Is a membrane that lines the
outer surface of all bones
except at the joints of long
bones.
 Is made up of :
 Outer FIBROUS layer :
made up of white
connective and elastic
tissue.
 Inner CAMBIUM layer :
which has a looser
composition, is more
vascular and contains
pregenitor cells that can
change to osteoblast.
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PERIOSTEUM

10. 
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BLOOD SUPPLY OF BONE
 Long bones have three
blood supplies
-Nutrient artery
(intramedullary) 80-85%
-Periosteal vessels
- Metaphyseal vessels

11. 11
HEALING AFTER FRACTURE
FIXATION
 DIRECT/PRIMARY:
 Mechanism of bone healing seen
when there is no motion at the
fracture site (i.e. rigid internal
fixation).
 Does not involve formation of
fracture callus.
 Osteoblasts originate from
endothelial and perivascular cells.

12. 12
CONTD:
 INDIRECT/SECONDARY:
 Mechanism for healing in
fractures that are not rigidly
fixed.
 Bridging periosteal (soft) callus
and medullary (hard) callus re-
establish structural continuity.
 Callus subsequently undergoes
endochondral ossification.

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TYPES OF BONE HEALING
 PRIMARY
1. 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.
2. 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 .

14. 14
CONTD:
 SECONDARY:
It is usual type consisting of
formation of callus either of
cartilaginous or fibrous. This
callus is later replaced by
lamellar bone. It is comparable
to healing of soft tissue by filling
of gaps with vascular
granulation tissue.

16. Hematoma Formation (1st)
Last for less than 7 days
Tissue disruption results in hematoma at
the fracture site
Local vessels thrombose causing bony
necrosis at the edges of the fracture
Increased capillary permeability results in a
local inflammatory area
Osteoinductive growth factors stimulate the
proliferation and differentiation of
mesenchymal stem cells

17. Cellular Formation Phase(2nd)
• 2-3 weeks
• Acidic environment but turning
neutral
• Influx of endosteal cells from
cambium layer produce a fibrous
callus (environment has high oxygen
tension) then cartilage (has a low
oxygen tension environment)

18. Callus Formation Phase (3rd)
4-12 weeks
Fibroblast deposit collagen in the
granulation tissue
Soft Callus is formed (Unorganized
network of woven bone);
Internal callus (grows quickly to create
rigid immobilization)
The hard callus lasts 3-4 months.
Hard callus – a gradual connection of bone
filament to the woven bone (Acts like a
temporary splint)
Bone is beginning to strengthen and
immobilize
If proper immobilization does not occur;
cartilage will form instead of bone

19. OssificationPhase (4th)
•1- 4 Years
•It will occur with adequate
immobilization
•Bone ends become crossed with a new
Haversian system that will eventually lead
to the laying down of primary bone
Fracture is bridged and united

20. Remodeling Phase (5th)
•Remodeling hard callus to compact bone or woven bone is gradually converted
to lamellar bone.
•May take a few years
•Medullary cavity is reconstituted
•Bone is restructured in response to stress and strain

21. 
1. LOCAL FACTORS.
2. SYSTEMIC FACTORS.
3. ELECTROMAGNETIC FACTORS.
4. TREATMENT FACTORS.
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FACTORS INFLUENCING BONE HEALING

22. 
A.Type of bone:
Calcellous (spongy) bone V/S cortical bone.
B. Degree of Trauma:
Extensive soft tissue injury and comminuted #‘s V/S Mild
contusions
C.Vascular Injury:
Inadequate blood supply impairs healing. Especially vulnerable areas
are the femoral head, talus, and scaphoid bones.
D. Degree of Immobilization:
Immobilized for vascular ingrowth and bone healing to occur.
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1.LOCAL FACTORS

23. 
 Repeated disruptions of repair tissue, especially to areas with
marginal blood supply or heavy soft tissue damage, will impair
healing.
E.Type of Fractures: Intraarticular fractures communicate with synovial
fluid, which contains collagenases that retard bone healing V/S Open
fractures result in infections V/S
Segmental fractures have disrupted blood supply.
F.Soft Tissue Interposition:
G.others: Bone death caused by radiation, thermal or chemical burns
or infection.
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CONTD..

24. 
A.Age:
Young patients heal rapidly and have a remarkable ability to
remodel V/S old .
B.Nutrition:
An adequate metabolic stage with sufficient carbohydrates
and protein is necessary.
C.Systemic Diseases:
and those causing an immunocompromised state will likely
delay healing. Illnesses like Marfan’s syndrome and Ehlers-
Danlos syndrome cause abnormal musculoskeletal healing.
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4.SYSTEMIC FACTORS

25. D.HORMONES:
Estrogen
Stimulates fracture healing through receptor mediated
mechanism.
Thyroid hormones
Thyroxine and triiodothyronine stimulate osteoclastic bone
resorption.
Glucocorticoids
Inhibit calcium absorption from the gut causing increased PTH
and therefore increased osteoclastic bone resorption.
Parathyroid Hormone
Growth Hormone
Mediated through IGF-1 (Somatomedin-C)
Increases callus formation and fracture strength
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26. 
In vitro bone deformation produces piezoelectric currents
and streaming potentials.
Electromagnetic (EM) devices are based on Wolff’s Law
that bone responds to mechanical stress: Exogenous EM
fields may simulate mechanical loading and stimulate
bone growth and repair
TYPES ARE :
 Ultrasound.
 Direct electrical current.
 Pulsed electromagnetic fields (PEMF).
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5.ELECTROMAGNETIC FACTORS

27. 
 Apposition of fracture fragments.
 Loading and micromotion .
 fracture stabilization.
 Rigid fixation.
 Bone grafting.
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6.Treatment factors

28. 
 Malunion
 Delayed union
 Nonunion
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Complication of Fracture Healing

29. 
MAL UNION
 A malunited Fracture is one that has healed with the
fragments in a non anatomical position.It is due to
inaccurate reduction and/or ineffective
immobilization
 Malunion can Impair fucntion by
 Abnormal joint surface
 Rotation or Angulation
 Overriding
 Movement of neighbouring joint may be blocked

30. 
Delayed Union
 The exact time when a given fracture should be
united cannot be defined
 Union is delayed when healing has not advanced at
the average rate for the location and type of fracture
(Btn 3-6 mths)
 Treatment usually is by an efficient cast that allows
as much function as possible can be continued for 4
to 12 additional weeks

31. 
Nonunion
 FDA defined nonunion as “established when a
minimum of 9 months has elapsed since fracture
with no visible progressive signs of healing for 3
months”
 Every fracture has its own timetable (ie long bone
shaft fracture 6 months, femoral neck fracture 3
months)