Principles internal fixation (Dujo)

Question 1

Principles internal fixation

Answer 1

1. Anatomic reduction
2. Stable internal fixation
3. Atraumatic technique of bone and soft tissue
4. Early pain-free return to function

Question 2

Screw anatomy

Answer 2

• Thread
  
  • grooves
• Pitch
  
  • frequency of threads
• Head
  
  • top
• Flute
  
  • tip

Question 3

Size of screw

Answer 3

• diameter at thread

Question 4

Core

Answer 4

• Diameter between threads…?
  
  • strength of the screw

Question 5

Tapping

Answer 5

• Makes threads in bone ahead of screw placement
  
  • there are self tapping screws

Question 6

Cancellous screw

Answer 6

• aggressive threads
• smaller core
• grips better in soft bone
• not as strong

Question 7

Locking screws

Answer 7

• core diameter is thicker
• threads less pronounced
• threads at the head
  
  • engage with the plate

Question 8

Lag screw

Answer 8

• Threads don’t exist along entire length
• Don’t necessarily need lag screws to place screws in a lag fashion

Question 9

Lag fashion

Answer 9

• Screw placed to result in compression
  
  • overdrill cis-cortex
  • we want engagement in trans cortex only

Question 10

Countersinking

Answer 10

• Drill bit to drill a hole in cis cortex that will allow screw head to sink into cis cortex some

Question 11

Classification of bone plates

Compression plate

Answer 11

• Compression plate: tilted wells for screws
  
  • Fracture reduced
  • compression applied across fracture gap
  • Use with
    
    • transverse fractures
    • short oblique fractures
  • Dont use with
    
    • comminuted fractures

Question 12

Classification of bone plates

Neutralization plate

Answer 12

• Neutralization plate
  
  • used in comminuted fractures
  • bone column reconstructed and plate placed over reconstruction

Question 13

Classification of bone plates

Buttress plates

Answer 13

• Plate bridges fracture gap and takes on entire load
  
  • used when bone column not reconstructed
  • has to be very strong

Question 14

Classification of bone plates

Dynamic compression plate (DCP)

Answer 14

• Dynamic compression plate
  
  • holes are oval, contain an incline plane
    
    • allows screws to produce plate translocation when tightened
    • screws need to be placed eccentrically

Question 15

Classification bone plates

Limited contact dynamic compression plates (LC-DCP)

Answer 15

• Dynamic compression plate
  
  • has scallps on underside
  • limits damage of underlying periosteum

Question 16

Classification bone plates

Locking plates

Answer 16

• ‘internal’ external fixator
• screws engage threads that have been made in bone
  
  • locks them onto plate
• result in very strong constructs
• Don’t need as many cortices as a non-locking plate

Question 17

Fracture fixation

THink about

Answer 17

• Plan your sx before anesthesia
  
  1. implant system
  2. implant size
  3. how old is patient
  4. compliance of owners
  5. underlying dz
  6. cost
  7. temperament of patient
  8. type of fracture
  9. location

Question 18

Reduction

Answer 18

• reduction
• bone holding forceps
• place implant on tension side
  
  • minimum 4 cortices wtih locking plates
  • minimum of 6 cortices with non-locking plates
• contour plate
• locking plates don’t need perfect contouring

Question 19

Screw placement

Answer 19

• Keep screws 4-5 mm from fracture line
• don’t disrupt periosteum if possible
• place plate directly on bone

Question 20

For sx

Answer 20

• have a back-up plan
• don’t break sterility

Question 21

Screw placement

technique

Answer 21

• Drill
• Measure
• Tap
• Screw
• Repeat

Question 22

Reasons for plate removal

Answer 22

• Location
• Loose implants
• Infection
• Environment
• Excessive stress protection