Fractures and bone healing

1. Fractures and Bone
Healing

2. Response to Mechanical Stress
Wolff’s law – a bone grows or remodels in
response to the forces or demands placed
upon it
Observations supporting Wolff’s law include
 Long bones are thickest midway along the shaft
(where bending stress is greatest)
 Curved bones are thickest where they are most
likely to buckle

3. Response to Mechanical Stress
 Trabeculae form along lines of stress
 Large, bony projections occur where
heavy, active muscles attach

4. Response to Mechanical Stress

5. Statistics
Fractures of extremities most common
More common in men up to 45 years of age
More common in women over 45 years of age
Before 75 years wrist fractures (Colles’) most
common
After 75 years hip fractures most common

6. Fractures
A fracture is any break in a bone.
 Fracture repair involves formation of a clot called a
fracture hematoma, organization of the fracture
hematoma into granulation tissue called a procallus
(subsequently transformed into a fibrocartilaginous [soft]
callus), conversion of the fibrocartilaginous callus into
the spongy bone of a bony (hard) callus, and, finally,
remodeling of the callus to nearly original form.
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7. Bone Fractures (Breaks)
Bone fractures are classified by:
The position of the bone ends after fracture
The completeness of the break
The orientation of the bone to the long axis
Whether or not the bones ends penetrate the skin

8. Common Types of Fractures
Magnitude and direction of force are determining
factors in type of fracture.
Closed
 – Bone fragments do not pierce skin
Open/compound
 – Bone fragments pierce skin
Displaced or undisplaced

9. Common Types of Fractures
Comminuted – bone fragments into three or
more pieces; common in the elderly
Spiral – ragged break when bone is excessively
twisted; common sports injury
Depressed – broken bone portion pressed
inward; typical skull fracture
Compression – bone is crushed; common in
porous bones

10. Common Types of Fractures
Epiphyseal – epiphysis separates from
diaphysis along epiphyseal line; occurs where
cartilage cells are dying
Greenstick – incomplete fracture where one
side of the bone breaks and the other side
bends; common in children

11. Common Types of Fractures

12. Common Types of Fractures

13. Common Types of Fractures

14. Common Types of Fractures
 Named for shape or position of fracture line
 Common types of fracture
 Pott’s -- distal fibular fracture
 Colles’s -- distal radial fracture
 stress fracture -- microscopic fissures from repeated strenuous
activities
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15. Transverse fracture
Usually caused by directly applied force to
fracture site

16. Spiral (Oblique)
Caused by violence transmitted through limb
from a distance (twisting movements)

17. Greenstick
Occurs in children: bones soft and bend
without fracturing completely

18. Compression (Crush) fractures
Fracture in cancellous bone: result of
compression (osteoporosis)

19. Burst fracture
Occurs in short bones, e.g. vertebra from
strong direct pressure such as impaction of
disc.

20. Avulsion fracture
 Caused by traction, bony fragment usually torn off by a tendon or
ligament.
 What muscle group attaches to this bony prominence and what
nerve also runs in close proximity?
 Forearm flexors (common flexor origin) ulnar nerve

21. Fracture dislocation/subluxation
Fracture involves a joint: results in
malalignment of joint surfaces.

22. Impacted fracture
Bone fragments are impacted into each other.

23. Comminuated fracture
Two or more bone pieces - high energy
trauma

24. Comminuated fractures can require serious
hardware to repair.

25. Stress Fracture
 Abnormal stress on normal bone (fatigue
fracture) or normal stress on abnormal bone
(insufficiency fracture).

26. Functions of the X-ray
Localizes fracture and number of fragments
Indicates degree of displacement
Evidence of pre-existing disease in bone
Foreign bodies or air in tissues
May show other fractures
MRI, CT or ultrasound to reveal soft tissue damage

27. Repair/Healing of Bone
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Healing is faster in bone than in cartilage due to lack
of blood vessels in cartilage
Healing of bone is still slow process due to vessel
damage
Clinical treatment
closed reduction = restore pieces to normal position by
manipulation
open reduction = realignment during surgery

28. How to Handle Fractures
 Reduction
 Open reduction
– Allows very accurate reduction
– Risk of infection
– Usually when internal fixation is needed
 Manipulation
– Usually with anesthesia
 Traction
– Fractures or dislocation requiring slow therapy

29. Fracture Fixation
4-12 weeks
External fixation
Internal fixation
 Intermedually nails, compression plates
Frame fixation

30. External fixation
Used for fractures that are too unstable for a
cast. You can shower and use the hand gently
with the external fixator in place.

31. Frame fixation
Allows correction of deformities by moving
the pins in relation to the frame.

32. Internal fixation

33. Repair of a
Fracture
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34. Stages in the Healing of a Bone Fracture
Hematoma formation
Torn blood vessels
hemorrhage
A mass of clotted
blood (hematoma)
forms at the fracture
site
Site becomes swollen,
painful, and inflamed
3-4 hours 1
Hematoma
Hematoma formation

35.  The fibrocartilaginous callus forms when:
Osteoblasts and fibroblasts migrate to the fracture
and begin reconstructing the bone
Fibroblasts secrete collagen fibers that connect
broken bone ends
Osteoblasts begin forming spongy bone
Osteoblasts furthest from capillaries secrete an
externally bulging cartilaginous matrix that later
calcifies

36.  Fibrocartilaginous
callus forms
 Granulation tissue
(soft callus) forms
a few days after
the fracture
 Capillaries grow
into the tissue and
phagocytic cells
begin cleaning
debris
2 Fibrocartilaginous
callus formation
External
callus
New
blood
vessels
Spongy
bone
trabeculae
Internal
callus
(fibrous
tissue and
cartilage)

37.  Bony callus formation
New bone trabeculae appear
in the fibrocartilaginous callus
Fibrocartilaginous callus
converts into a bony (hard)
callus
Bone callus begins 3-4 weeks
after injury, and continues
until firm union is formed 2-3
months later 3 Bony callus
formation
Bony
callus of
spongy
bone

38. Bone remodeling
Excess material on
the bone shaft
exterior and in the
medullary canal is
removed
Compact bone is laid
down to reconstruct
shaft walls
4 Bone remodeling
Healing
fracture

39. THANK YOU