A bone fracture is a broken bone that occurs when a force impels against a bone that is stronger than it can structurally withstand.Bone healing refers to complex and sequential events that occur to restore injured bone to pre-injury state.

1. Biomechanics Of Fracture And
Fracture Healing
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2. Contents
 Biomechanics of Bone
• Biomechanical Characteristics of Bone
• Anisotropic Response
• Viscoelastic Response
• Mechanical Loading of Bone

3. Bone Fracture
• What Is A Bone Fracture?
• What Causes A Broken Bone?
• What Symptoms A Broken Bone?
• Immediate Treatment For A Bone Fracture
• Types of Fracture
Fracture Healing And Repair
• What Is The Process of Fracture Healing
• Types for Bone Healing
• The Sequence of Fracture Healing
• Factors Affecting Bone Healing

4. Biomechanical Characteristics of Bone
• Bone is a composite of mainly collagen and minerals
(hydroxyapatite, or calcium)
• Collagen has a low E, high tensile strength, low
compressive strength
• Hydroxyapatite is stiff, brittle, high compressive
strength
viscoelastic
ductile
brittle
one of the body’s
hardest structures
Inorganic Components
(e.g., calcium and phosphate)
Organic Components
(e.g. collagen)
H2O
(25-30%)
)65-70%(
)25-30%(

5. Anisotropic Response
• Bone is considered anisotropic because it
responds differently if forces are applied in
different directions.
• Bone can handle large forces applied in the
longitudinal plane (tension and compression).
• bone is not as strong in handling forces applied
transversely across its surface.
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6. Anisotropic Behavior of Cortical Bone

7. Viscoelastic Response
Behavior of bone is dependent on
rate at which load is applied.

8. Mechanical Loading Of Bone

9. Fracture Patterns
tension compression bending torsion

10. Compressive Loading
Vertebral fractures
• cervical fractures
e.g. gymnastics
• lumbar fractures
e.g. weight lifters, linemen, or gymnasts

11. Tensile Loading
Main source of tensile load is muscle.

12. Shear Forces
It is created by the application of compressive,
tensile or a combination of these loads.

13. Bending Forces
Usually a 3- or 4-point force application
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14. Torsional Forces
Caused by a twisting force produces shear, tensile, and compressive loads.
spiral fracture can develop from this load.

15. Bone Fracture

16. What Is A Bone Fracture?
A bone fracture is a broken bone that
occurs when a force impels against a
bone that is stronger than it can
structurally withstand.

17. What Causes A Broken Bone?
 There are three common causes of bone fractures:
•Trauma
•Medical conditions that weaken the bone
•Overuse injuries

18. What Symptoms A Broken Bone?
• pain
• inability to move or put
weight on the injured body
part
• swelling
• bruising
• bleeding (if there is an open wound)
• deformity

19. Immediate Treatment For A Bone Fracture
Fractures require medical treatment. See a doctor (preferably an
orthopedist) if you suspect a bone fracture. X-rays are often used to
located and assess fractures. The fracture may require :
• Casting
• Traction
• External Fixation
• Internal Fixation

20. Casting
External Fixation
Internal Fixation

21. Fracture Penetration Of Skin
Compound
Simple
Orientation Of Break
Linear
Transverse
Position Of Bone Ends
Displaced
Non Displaced
Completeness Of Break
Complete
Incomplete

22. Compound And Simple Fracture
• Compound Fracture
A compound fracture, also known as an open fracture,
occurs when the skin has been broken through.
• Simple Fracture
A simple fracture, also called a closed fracture, is any
type of fracture that has broken into two pieces, and
has not broken through the skin.

23. Linear And Transverse Fracture
• Linear Fracture
Linear Fracture is a fracture that extends parallel to
the long axis of a bone but does not displace the
bone tissue.
• Transverse Fracture
Transverse fracture implies a fracture line that is transverse
to the long axis of the bone.

24. Displaced And Non Displaced Fracture
• Displaced Fracture
When your bone snaps into two or more parts, this is
called a displaced fracture. Your bone will no longer
be aligned in this case.
• Non Displaced Fracture
A non-displaced fracture is the one in which your
bone cracks in only one place and doesn't move to
change alignment.

25. Complete And Incomplete Fracture
• Complete Fracture
A complete fracture involves a break across the entire
section of the bone.
• Incomplete Fracture
An incomplete fractures involves a break through only
part of the cross-section of the bone.

26. On Basis of Pattern of Fracture
• Transverse
• oblique
• spiral
• comminuted
• segmental

28. Fracture Healing And Repair

29. What Is The Process Of Fracture Healing
Bone healing refers to complex and sequential events that occur to
restore injured bone to pre-injury state.
Types for Bone Healing
•Direct Healing
•Indirect Healing

30. Components of Direct Bone Healing
• Without callus formation
• Contact Healing
Direct contact between the fracture ends allows healing to be with
lamellar bone immediately.
• Gap Healing
Gaps less than 200-500 microns are primarily filled with woven bone
that is subsequently remodeled into lamellar bone.
Larger gaps (Gap between fracture fragments > 1mm) arehealed by indirect
bone healing.

31. Lamellar Bone vs Woven Bone
• Woven bone is characterized by haphazard
organization of collagen fibers and is
mechanically weak.
• Lamellar bone is secondary bone created
by remodeling of woven bone . Lamellar
bone has a regular parallel alignment of
collagen into sheets (lamellae) and is
mechanically strong.
Woven bone Lamellar bone

32. Indirect Bone Healing
Indirect bone healing is the natural response to fractures. It requires
relative stability and leads to callus formation.

33. The Sequence Of Fracture Healing Involves Five Stages
• hematoma
•Inflammation
• Soft Callus
• Hard Callus
• Remodeling
Three Phases Of Healing
Inflammatory
phase
Reparatory phase
• Soft Callus
• Hard Callus
Remodeling
phase
hematoma

34. How Long Does Bone Healing Take?

35. Hematoma
• Fracture of the bone destroys the cells, blood vessels,
bone matrix, periosteum and muscles.
• Hematoma formation

36. Inflammation
• inflammatory phase is identical to the typical inflammatory
response of most tissues to traumatic injury.
• peaks within 48 hours and is quite diminished by 1 week
after fracture.
• Vasodilation and hyperemia, presumably mediated by
histamines, prostaglandins, and various cytokines,
accompany invasion of the injury site by neutrophils,
basophils, and phagocytes that participate in clearing away
necrotic debris.

37. Inflammation

38. Soft Callus
• After inflammation subsides fibroblasts and chondrocytes appear in the
site leading to callus formation.
• Callus – comprises fibrous tissue , cartilage , woven bones.
• Soft callus – forms in the central region of the fractured bone Primarily
of cartilage and fibrous tissue.

39. Soft Callus

40. Hard Callus
• the bone that is formed in the periphery of the callus by intramembranous bone
formation.
• endochondral ossification , hard callus enlargement, increase in the stability of
fractured fragments

41. Hard Callus

42. Hard Callus Stage of Healing

43. Remodeling
The final step takes several months and is called remodeling
• Spongy bone is replaced by compact bone.
• The fracture line disappears, but evidence of the break remains.
• The remodeling phase takes 3 to 5 years depending on factors such as age or
general condition

44. Remodeling

45. Radiography Image For Describe Bone Fracture Healing

46. Summary of Bone Healing

47. Exercise Affecting Bone Healing
• Bone tissue alters its strength in response to changes in mechanical stress
• Under stress, bone tissue becomes stronger through deposition of mineral salts and production
of collagen fibers by osteoblasts and fibroblasts
• Unstressed bones diminishes because of the loss of bone minerals and decreased numbers of
collagen fibers
• The main mechanical stresses on bone are those that result from the pull of skeletal muscles
and the pull of gravity
• Weight-bearing activities help build and retain bone mass
• Wolff's law: If loading on a particular bone increases, the bone will remodel
itself over time to become stronger to resist that sort of loading.

48. Factors Affecting Bone Healing
•Age
•Nutrition
•Systemic Diseases
•Hormones
• Type of bone
• Associated vascular injury
• Inadequate immobilisation
• Inadequate reduction
• Infection
• Local pathology