ao plate screw

1. AOTrauma Principles Course
Fracture fixation using the
locking compression plate (LCP)

2. Learning outcomes
• Understand the different functions of conventional and locking head
screws.
• Understand the different concepts of fracture fixation using locking
compression plates.
• Apply the principles to clinical usage—“know when which principle
needs to be applied in a clinical example”.
• Understand the advantages of locked plates in special clinical
circumstances (eg, osteoporosis).

3. Locking compression plate (LCP)
dynamic
compression
unit
conical and
threaded
unit

4. Different types of screws
Conventional screws
Cortex screw (with or without shaft)
Cancellous bone screw (with or
without shaft)
Locking head screws (LHS)
Self-tapping LHS
Self-drilling, self-tapping LHS

5. Mechanics/biomechanics of plate/screw
fixation
Plate fixation with conventional screws
•
•
•
•
Screws in tension
Plate/bone friction
Compression at fracture site
Disturbed blood supply
Plate fixation with locking head screws (LHS)
•
•
•
•
Screws in shear
Noncontact plate
No compression of fracture
Preserved blood supply

6. Functions of conventional screws (slide 1 of 2)
• Plate screw
-
-
Preload and friction is applied to create force
between plate and bone
• Lag screw
-
-
Interfragmentary compression screw; always
inserted before fixation of the plate with LHS
• Compression screw (eccentric screw)
- Positioned in the dynamic compression unit
(DCU)
• Position screw
-
-
Keeps two fragments in position without
compression

7. Functions of conventional screws (slide 2 of 2)
Reduction screw
Screw inserted through a
plate hole to pull fracture
fragments toward the plate
Reduction of a butterfly
fragment
(no interfragmentary
compression)

8. Drawbacks of fixation with conventional
screws
• Compression of the periosteum and resulting damage of
the blood supply to the bone
• Primary loss of reduction
• Secondary loss of reduction
primary loss of reduction secondary loss of reduction

9. Functions of locking head screws (LHS)
•
•
•
Always in combination with a plate
Never as lag screw
Never cross an unreduced fracture with a
LHS
• Fixation screw
- Fix the plate to the bone
• Position screw
- Keeps two fragments in correct
relative anatomical position

10. Features and advantages of LHS
• Axial and angular stability
• Not preloaded
• Cannot be over-tightened
• Higher resistance against bending loads
• Monocortical insertion is possible (shaft and good bone quality
needed)
• No primary loss of reduction
• No or less screw loosening, no or less secondary loss of reduction

11. Features and advantages of locked
plates
• Screw-plate system with angular and axial stability
• Locked internal fixator/noncontact plate
• Individual blade plate

12. Biological advantages
• Reduced compression of the periosteum
• Protects blood supply to the bone
• Callus formation/bone healing under the plate
bone after plating with a DCP bone after plating with a LCP

13. Clinical advantages
•
•
•
•
Osteoporosis
LHS cannot be over-tightened
Higher resistance against bending forces
No secondary screw loosening
•
•
•
•
Epimetaphyseal fracture/short fragment
Angular and axial stability
No primary loss of reduction
Blade plate
•
•
•
MIPO or less invasive technique
Precise prebending of the plate is
not required
No primary loss of reduction
primary loss of
reduction
Technical reason
Primary loss of
reduction
bone necrosis under the plate
secondary
loss of
reduction

14. Drawback of fixation with LHS
• Screw insertion is only possible in a 90° angle
• No bicortical insertion of self-drilling, self-tapping screws
(use self-tapping screws only for bicortical insertion
• Possible loss of the feel for the quality of the bone during
screw insertion and tightening
• Screw jamming and difficult implant removal

16. Planning and decision making
•
•
•
• The stability of the fracture fixation determines bone
healing
How much stability is necessary?
Absolute or relative stability
What kind of bone healing is best for the type of
fracture?
Direct or indirect bone healing
Which are the technical limitations?
(eg, iatrogenic trauma)
direct bone healing (histological photo) indirect bone healing (x-ray)

17. Planning and decision
making―influence of moti
Abolish fracture site motion
→ absolute stability
leading to direct healing
Factors influencing motion:
•
•
•
•
Plate properties
Screw properties
Interface properties (coupling)
Fracture site properties
on
Reduce fracture site motion
→ relative stability
leading to indirect healing

18. Preoperative planning
• Factors determining the method and principle
• (grade of stability) of the fracture fixation:
• Length of plate and/or shape of plate
• Type and function of screw
• Position and number of screws

19. Characteristics of the LCP system:
different sizes and adjusted to anatomy
Standard plates
Special and anatomically preshaped plates

20. Compression with plates
Principle
Method
= absolute stability
= compression
Technique = conventional plating (ORIF)
• Different plate functions:
Protection plate
Compression plate
Buttress plate
-
-
-
- Tension band plate
• Indications:
- Simple fractures (shaft and
metaphysis)
- Articular fractures
- Delayed union or nonunion
(same use as the LC-DCP)

21. Compression with plates—prerequisites
• Precise anatomical reduction (direct, open)
• Stable fixation with interfragmentary compression
• Good bone quality
• Exact prebending of the plate

22. Tibial shaft fracture, 42-A1
53-year-old man, skiing injury
Principle:
Method:
absolute stability
interfragmentary compression
Technique: conventional plating (ORIF)
first step
preoperative x-rays postoperative x-rays follow-up x-rays
Case from Christian Ryf, Davos

23. Closed forearm fracture, 22-B3
17-year-old man, soccer injury
2.
3.
1.
1.
Principle:
Method:
absolute stability
interfragmentary compression
Technique: conventional plating (ORIF)
preoperative x-rays postoperative x-rays
Case from Emanuel Gautier, Fribourg
clincal picture of plate insertion

24. Closed radial shaft fracture, 22-A2 (slide 1 of 2)
25-year-old man, fall on arm
Principle:
Method:
absolute stability
interfragmentary compression
Technique: conventional plating (ORIF)
preoperative x-rays postoperative x-rays
Case from Michael Wagner, Wien
clincal pictures of plate insertion

25. Closed radial shaft fracture, 22-A2 (slide 2 of 2)
25-year-old man, fall on arm
Case from Michael Wagner, Wien
follow-up x-rays and clinical pictures 6 weeks postoperatively

26. Articular multifragmentary tibial head
fracture, 41-C3 (slide 1 of 2)
19-year-old woman, fall from horse
Principle:
Method:
absolute stability
interfragmentary compression
Technique: conventional plating (ORIF) Case from Michael Wagner, Wien
preoperative x-rays, AP and lateral view CT scan in sagittal plane
CT scan on frontal plane

27. Articular multifragmentary tibial head
fracture, 41-C3 (slide 2 of 2)
19-year-old woman, fall from horse
Case from Michael Wagner, Wien
postoperative x-rays follow-up x-rays after 1 year

28. Splinting with plates
Principle
Method
= relative stability
= splinting/locked splinting
Technique = less invasive or MIPO, following
indirect reduction
•
•
• Plate functions:
• Bridging plate with conventional screws
• Locked internal fixator
• Indications:
• Multifragmentary metaphyseal/diaphyseal
fractures
Osteoporosis
MIPO

29. Splinting with locked plates—
prerequisites
• Indirect, closed, no precise reduction
• Long plate
• Fixation with LHS only on main fragments
No screws in fracture zone
•
• Prebending of plate not necessary
• Elastic fixation to achieve relative stability

30. Splinting with locked plates—features
and advantages
•
•
•
•
•
Biological
MIPO > soft-tissue preservation
Locked elastic fixation: relative stability > callus formation
No or minimal contact of the plate to the bone > undisturbed blood
supply
Monocortical LHS in the diaphysis preserve:
-
-
-
medullary blood circulation
distant cortex
adjacent soft tissues
•
•
•
•
•
Technical/mechanical
No need of exact anatomical preshaping of the plate
No primary loss of reduction
Angular and axial stability of screws > less screw loosening
Note: the plate takes over the entire load

31. Splinting with locked plates—
shortcomings and disadvantages
• Stability of the fixation depends on the rigidity of the
construct
• Plate takes over the entire load
• MIPO is a demanding/difficult technique (closed indirect
reduction)

32. Multifragmentary distal femoral fracture,
33-A3 (slide 1 of 2)
87-year-old woman
Principle:
Method:
relative stability
locked splinting
Technique: MIPO
preoperative x-rays
postoperative x-rays after bridging of the
multifragmentary fracture with a minimally invasive
approach.
follow-up x-rays
Case from Christoph Sommer, Chur

33. Multifragmentary distal femoral fracture,
33-A3 (slide 2 of 2)
87-year-old woman
postoperative x-rays after 3 months clinical pictures after 3 months follow-up x-rays after 5 months
Case from Christoph Sommer, Chur

34. Combination of compression and
splinting with one plate
• A combination of both methods is only possible when
two different
• fractures occur in the same bone.
•
•
•
Indications
Segmental fractures
Articular fracture with additional
metaphyseal/diaphyseal fracture
• Note: never combine the
methods in one fracture!

35. Multifragmentary proximal tibial fracture,
41-C2
83-year-old woman (with osteoporosis), hit by car as pedestrian
Articular fracture
Principle: absolute stability
Method: interfragmentary compression
Technique: conventional plating (ORIF)
Case from Michael Wagner, Wien
preoperative x-ray postoperative x-ray follow-up x-rays after 6 months follow-up x-rays after 1 year
Multifragmentary metaphyseal fracture
Principle: relative stability
Method: splinting
Technique: MIPO

36. Open tibial shaft fracture, 42-C2 (slide 1 of 2)
50-year-old man, skiing injury
Simple metaphyseal fracture
Principle: absolute stability
Method: compression
Technique: ORIF
preoperative x-ray reduction and fixation postoperative x-rays
Case from Christian Ryf, Davos
Multifragmentary shaft fracture
Principle: relative stability
Method: locked splinting
Technique: less invasive

37. Open tibial shaft fracture, 42-C2 (slide 2 of 2)
50-year-old man, skiing injury
follow-up x-rays after 6 weeks follow-up x-rays after 6 months
Case from Christian Ryf, Davos
follow-up x-rays after 8 months
indirect
bone healing
direct
bone healing

38. Summary/take-home message
• Two different methods and principles:
-
-
compression—absolute stability
splinting—relative stability
• Essential points for correct practical application:
-
-
preoperative planning
no mixture of principles/methods in same fracture

39. Summary/take-home message
• Compression plating after anatomical reduction in
articular and simple fractures.
• Splinting/bridge plating in multifragmentary fractures to
minimize amount of additional trauma (MIPO).
• Locking head screws always with locking compression
plates; better fixation, convenient in osteoporosis,
technical and biological reasons.