Fractures

Question 1

Physiology of Bone types

Answer 1

• cortical bone (compact bone) = located in exterior part, more dense
• cancellous bone (spongy bone) = less dense, follow the lines of force

Question 2

Mechanism of fracture: What is Wolff’s law?

Answer 2

• bone adapts to increased use (e.g. physical activity) or disuse (e.g. bed rest)

Question 3

4 Causes of fracture

Answer 3

1. Direct trauma (struck by heavy object)
2. Indirect trauma (fall on outstretched hand)
3. Pathological (osteoporosis due to weakened bone)
4. Stress/ fatigue (repeated actions)

Question 3

strength and stiffness of bone tissue (elastic, plastic, viscoelastic, anisotrophic)

Answer 3

• elastic (ductile; deform greatly before breaking)
• plastic (permanent deformation)
• viscoelastic (loading rate increase; elasticity and strength increase) —> bone# sooner when load is applied slowly
• anisotrophic (withstand great force - same direction of the bone e.g. compression) ; (least strength - 90 degree to the bone e.g. shear)

Question 4

Classification of fracture

Answer 4

Location + pattern + with/out displacement + with/out angulation + close (simple)/open (compound)#

Question 5

Clinical signs of fracture

Answer 5

• 1/ Look
  
  • visible bruises
  • local swelling
  • visible deformity
• 2/ Feel
  
  • pain during movement
  • localized tenderness
  • palpable deformity
  • muscle spasm
• 3/ Move
  
  • Crepitus or grating between bone ends
  • Functional disturbance

Question 6

Healing process of fracture (5 stages)

Answer 6

1. Haematoma formation
2. Subperiosteal & Endosteal Cellular Proliferation
3. Stage of cellus
4. Stage of consolidation
5. Stage of remodeling

Question 7

Healing process of fracture:
What is Haematoma formation? How long does it last?

Answer 7

Release of Proliferating Stimulating Factor (PSF) chemicals by blood when blood vessels broken.

Immediate-few hours

Question 8

Healing process of fracture:
What is Subperiosteal & Endosteal Cellular Proliferation? How long does it last?

Answer 8

Cells from the deep surface of the periosteum (pre-cursors of the bone making cells, osteoblasts) move towards the fracture site

Few days

Question 9

Healing process of fracture:
What is Stage of cellus? How long does it last?

Answer 9

Osteoblasts replace cartilaginous tissues

form immature bone called a “fracture callus” / “bony callus” / “woven bone

Plastic easily deformed

2 weeks

Question 10

Healing process of fracture:
What is Stage of consolidation? How long does it last?

Answer 10

Woven bone becomes more mature bone (Lamellar Bone) through activity of osteoblasts

Can withstand some force

“Clinical Union” – Fracture site not tender to palpate

• for a fracture without surgical interventions, the injured body part should not be mobilized before this stage

2-3 weeks

Question 11

Healing process of fracture:
What is Stage of remodeling? How long does it last?

Answer 11

Union completed

Osteoclasts remove excess callus and osteoblasts lay down lamellar bone along lines of (in the direction of) mechanical stresses

12-18 months

Question 12

Factors affecting fracture healing

Answer 12

• Age
• Pattern of #
  – Openness, displacement, etc
• Blood supply
• Infection
• Lack of Vitamin C
  – May delay growth of granulation tissue
• Interposition of muscle between bony fragments
  – May obstruct normal repair process
• Inadequate immobilization if gap is wide

Question 13

General medical management

Answer 13

1. Fracture Reduction
2. Immobilize
3. Preservation of fx

Question 14

General medical management:
Definition of Fracture Reduction + types of reduction

Answer 14

restore normal bone alignment & approximate broken ends

1. Closed reduction - temporary traction —> then Plaster of Paris (POP)打石膏
2. *Open reduction - surgical with internal fixation devices

Question 15

General medical management:
Aims of immobilization

Answer 15

• Maintain reduction and prevent movement —> healing and remodeling
• 4-12 weeks
• not necessarily for # sites (ribs, clavicle, scapula, MT’s phalanges)

Question 16

General medical management: types of immobilization

Answer 16

• External immobilization
  
  • casting e.g. PoP
  • orthoses e.g. splint, brace
• External fixation devices
  
  • pins on distal and proximal # site —> maintain proper alignment
• Internal fixation
  
  • Small # fragments / fragments under large forces e.g. femur
  • Pins/screws/medullar rods/plates and screw

Question 17

Preseveration of fx

Answer 17

surrounding mm, joints, bone while # is healing

after # site is united —> remodel/strengthening the bone by exercise (muscular, activities, weight bearing)

Question 18

11 Common Complications of fracture

Answer 18

1. mal-union (e.g. dinner fork deformity)
2. joint stiffness due to adhesion of surrounding tissue
3. post-traumatic arthritis
4. delayed rupture of adjacent tendon/mm
5. nerve impingement/nerve palsy
6. delayed union/nonunion
7. avascular necrosis (AVN) = temporary or permanent loss of blood supply to the bone
8. reflex sympathetic dystrophy (RSD) e.g. pain, hypersensitivity, disuse atrophy, stiffness
9. Acute respiratory distress syndrome (life-threatening lung injury that allows fluid to leak into the lungs)
10. neuro-vascular injury
11. injury to tendon