AO principles

1. Pre Basic Course
Plates - form and function
Dr Sudarshan Bhandary

2. Plate : Form and Function
• To understand how changes in the design of
plates has evolved to meet the needs of the
patient
• To understand how you can use a plate in
several different ways to achieve different
types of fixation

3. Plate : Form and Function
• Absolute stability challenged by biological
fixation
• Osteosynthesis with plates has a firm place in #
treatment
• Articular #s require stable fixation
• Compromise of cortical blood supply a major
drawback of conventional plating

4. Plate : Form
• DCP
• Reconstruction plate
• Semitubular - 1/3rd Tubular Plate
• LC-DCP
• PC-FIX
• LCP
• LISS

5. DCP - 3.5 and 4.5
• First introduced in 1969 by Danis
• Revolutionary concept of compression plating
• Featured a new hole designed for axial compression
• Broad 4.5 for Femur & Narrow 4.5 for Humerus &
Tibia
• DCP 3.5 for Forearm, Fibula, Pelvis & Clavicle

6. • The screw hole in DCP is like a portion of an inclined
& angled cylinder
• When the screw is tightened it results in a movement
of bone fragment in relation to the plate

7. • Screw holes allow 1mm
compression
• Additional compression with
1 more eccentric screw before
locking first screw
• Oval shape allows 25*
inclination in longitudinal &
7* in transverse plane

8. Technique of application
3 drill guides
a) Concentric (Neutral) - Green collar - 0.1 mm offset
b) Eccentric (Load) - Gold collar - 1 mm offset
c) Universal for buttress mode

9. Problems with DCP
• Unstable fixation leads to fatigue & failure
• Strict adherence to principles of compression
• Compromised blood supply due to intimate
contact with underlying cortex
• “Refractures” after plate removal

10. LC-DCP
• Represents a design change
• Overcome problems with DCP
• Plate footprint reduced
• Minimized kinking at screw holes
• Allows more inclination of screw in
longitudinal plane

11. Technique of application
• New spring loaded drill guide
• Without pressure - Eccentric hole
• With pressure - Neutral

12. Tubular plates
• 3.5 system - 1/3rd Tubular
• 4.5 system - Semitubular
• Limited stability
• Collared hole
• Lateral malleolus
• Distal ulna / Olecranon
• Distal humerus

13. Reconstruction plates
• Deep notches between holes
• Accurate contouring in any
plane
• Pelvis
• Acetabulum
• Distal humerus
• Clavicle
• Olecranon

14. New Systems
• Abolish ill effects of plate to bone contact
• Concept of “Internal Fixator”
• PC - FIX = First implant designed
• Self tapping, unicortical, one length screws
• Locking head

15. LCP – Locking Compression Plate

16. LCP
• Latest in the evolution
• “ Internal fixator ”
• Combination of locking
screw with conventional
screw
• Extraperiosteal
location of plate

17. LCP
• Fixed angle stability
• Unicortical fixation
option
• Load & neutral position
of screws
• Conical screw head
• Large diameter

18. LISS-Less Invasive Stabilization System

19. LISS

20. Plate: Function

21. Principles of rigid internal fixation with plates
• Neutralization Plate
• Compression plate
• Buttress Plate
• Bridge Plate
• Tension Band Plate

22. Neutralisation Plate
• Used with lag screws , plate is
protective
• Neutralises the weight bearing forces
to protect the lag screws from axial
loading
• Lag screw generates forces of 3000 N

24. Compression plating
Techniques
• With dynamic compression principle
(DCP/LC-DCP)
• With tension devise
• By contouring plate
• Additional lag screw thro plate

25. Compression plating
• Compression through plate
- DC / LC-DC
• Compression with tension
devise

26. Compression with external devise

29. Contouring Plates
• To fit anatomy of bone
• Bending pliers
• Weakens plate

30. Buttress Plate
• Used when the fracture will only displace in one
direction.
• Only useful in metaphyseal fractures
• Applied so as to resist one deforming force

35. AO Organisation
☻ Philosophies and techniques of treatment will
change with time
☻ The philosophy that we exist to improve the
care given to our patients will last forever

36. THANK YOU