Internal fuxation

1. Basic Principles and
Techniques of Internal
Fixation of Fractures
Brett D. Crist, MD
Original Author: Dan Horwitz, MD; March 2004
Revision Author: Michael Archdeacon, MD, MSE; January 2006
New Author: Brett D. Crist, MD; October 2009

2. “Common” Definitions of Fracture Healing
• Union
– Bone’s mechanical stability restored to withstand normal
loads
• Clinically: no pain at fracture site
• Radiographically: 3 out of 4 cortices with bridging callus
• Delayed Union
– Fx not consolidated at 3 months, but progressive callus
• Non Union
– No improvement clinically or radiographically over 3
consecutive months
– A fibrocartilaginous interface
From: OTA Resident Course – Russel, T

3. High Energy vs. Low Energy
• “High Energy"
– Direct axial load or bending force
– Fall from height/Motor vehicle crash
– Soft tissue envelope significantly
damaged
– Comminuted fracture patterns
– Open fractures
• “Low Energy“
– Twisting mechanism or direct load on
weak bone
– Fall from standing
– Less soft tissue injury
– Simple fracture pattern
“High
Energy"
“Low
Energy"

4. Fracture Patterns
• Fracture patterns occur based on mode, magnitude
and rate of force application to bone
– Bending Load → transverse fx with wedge segment
• 3-point Bend →Wedge fragment
• 4-point Bend → Segmental fragment
– Torsional Load → oblique or spiral fx
– Axial Load → Articular impaction (Plateau, Pilon, etc.)

5. Fracture Patterns
• Understanding these patterns and the inherent
stability of each type is important in choosing the
most appropriate method of fixation and surgical
approach

6. High Rate of Healing
Spectrum of Healing
Absolute Stability =
10 Bone Healing
Relative Stability =
20 Bone Healing
Biology of Bone Healing
THE SIMPLE VERSION...
Fibrous Matrix >
Cartilage > Calcified
Cartilage > Woven Bone >
Lamellar Bone
Haversian
Remodeling
Minimal
Callus
Callus

7. Biology of Bone Healing
• Direct/Primary bone healing
– Requires rigid internal fixation
and intimate cortical contact –
absolute stability
– Minimal callus formation
– Cannot tolerate fracture gap
– Interfragmental compression will
minimize fracture motion
– Relies on Haversian remodeling
with bridging of small gaps by
osteocytes (cutting cones)
Figure from: OTA Resident Course - Russel

8. Biology of Bone Healing
• Indirect/Secondary Bone
Healing = CALLUS
– Divided into stages
• Inflammatory Stage
• Repair Stage
– Soft Callus Stage
– Hard Callus Stage
• Remodeling Stage
3-24 mo
– Relative stability
Figures from: OTA Resident Course - Russel

9. Practically speaking...
Primary/Direct Bone
Healing
• Simple fracture patterns
• See the fx during surgery
and directly reduce and
fix with:
– Lag screws
– Plates and screws
Secondary/Indirect Bone
Healing
• Complex fracture patterns
• Don’t directly see the
fracture during surgery
(use fluoro)
• Indirectly reduce the fx and
fix with:
– IM Rods
– Bridge plate fixation
– External fixation
– Cast

10. • Relative Stability
• Absolute Stability
– IM nailing
– Ex fix
– Bridge plating
–Cast
– Lag screw/ plate
– Compression plate
Fixation Stability

11. Absolute
(Rigid)
Relative
(Flexible)
Spectrum of Stability
Cast
IM Nail
Compression
Plating/ Lag
screw
Ex Fix
Bridge Plating

12. Practically speaking….
• Most fixation probably involves
components of both types of healing. Even
in situations of excellent rigid internal
fixation one often sees a small degree of
callus formation...

13. Relative
(Rigid)
Absolute
(Flexible)
No callus
Fixation Stability
Callus
Reality

14. Functions of Fixation
• Interfragmentary
Compression
– Lag Screw
• Plate Functions
– Neutralization
– Buttress
– Bridge
– Tension Band
– Compression
– Locking
• Intramedullary Nails
– Internal splint
• Bridge plate fixation
– Internal splint
• External fixation
– External splint
• Cast
– External splint
*Not internal fixation

15. Indications for Internal Fixation
• Displaced intra-articular fracture
• Axial, angular, or rotational instability that
cannot be controlled by closed methods
• Open fracture
• Polytrauma
• Associated neurovascular injury
MULTIPLE REASONS EXIST
BEYOND THESE...

16. Benefits of Internal Fixation
• Earlier functional recovery
• More predictable fracture alignment
• Potentially faster time to healing

17. Screws
• Cortical screws:
–Greater number of threads
–Threads spaced closer together (pitch is
(smaller pitch)
–Outer thread diameter to core
diameter ratio is less
–Better hold in cortical bone
• Cancellous screws:
– Larger thread to core diameter ratio
–Threads are spaced farther apart (pitch is
greater)
– Lag effect with partially-threaded screws
– Theoretically allows better fixation in
cancellous bone
Figure from: Rockwood and Green’s, 5th ed.

18. Lag Screw Fixation
• Screw compresses both
sides of fx together
– Best form of compression
– Poor shear, bending, and
rotational force resistance
• Partially-threaded screw
(lag by design)
• Fully-threaded screw (lag
by technique)

19. 1
2
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.
Lag Screws
• “Lag by technique”
• Using fully-threaded
screw
• Step One: Gliding hole =
drill outer thread diameter of
screw & perpendicular to fx
• Step Two: Pilot hole= Guide
sleeve in gliding hole & drill
far cortex = to the core
diameter of the screw

20. Lag Screws
• Step Three: counter sink near
cortex so screw head will sit
flush
• Step Four: screw inserted and
glides through the near cortex
& engages the far cortex which
compresses the fx when the
screw head engages the near
cortex
Figure from: Schatzker J, Tile M: The
Rationale of Operative Fracture Care.
Springer-Verlag, 1987.

21. Lag Screws
• Functional Lag Screw
- note the near cortex
has been drilled to the
outer diameter =
compression
• Position Screw - note
the near cortex has not
been drilled to the
outer diameter = lack
of compression & fx
gap maintained

22. Figure from: OTA Resident Course - Olsen
Lag Screws
• Malposition of screw, or neglecting to
countersink can lead to a loss of reduction
• Ideally lag screw should pass perpendicular to fx

23. Neutralization Plates
• Neutralizes/protects
lag screws from
shear, bending, and
torsional forces
across fx
• “Protection Plate"
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

24. Buttress / Antiglide Plates
• “Hold” the bone up
• Resist shear forces during
axial loading
– Used in metaphyseal
areas to support intra-
articular fragments
• Plate must match contour
of bone to truly provide
buttress effect

25. • Order of fixation:
• Articular surface compressed with
bone forceps and provisionally fixed
with k-wires
1. Bottom 3 cortical screws placed
• Provide buttress effect
2. Top 2 partially-threaded cancellous
screws placed
• Lag articular surface together
3. Third screw placed either in lag or
normal fashion since articular
surface already compressed
Buttress Concepts
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

26. Antiglide/Buttress Concepts
• Plate is secured by three black screws distal to
the red fracture line
• Axial loading causes proximal fragment to
move distal and to the left along fracture line
• Plate buttresses the proximal fragment
• Prevents it from “sliding”
• Buttress Plate
– When applied to an intra-articular fractures
• Antiglide Plate
– When applied to diaphyseal fractures

27. Bridge Plates
• “Bridge”/bypass
comminution
• Proximal & distal fixation
• Goal:
– Maintain length, rotation, &
axial alignment
• Avoids soft tissue
disruption at fx = maintain
fx blood supply

28. Tension Band Plates
• Plate counteracts natural
bending moment seen w/
physiologic loading of bone
– Applied to tension side to
prevent “gapping”
– Plate converts bending force
to compression
– Examples: Proximal Femur &
Olecranon

29. JOINT SURFACE
Tension band
Tension Band Theory
• The fixation on the opposite side from the articular surface
provides reduction and compressive forces at the joint by
converting bending forces into compression
• The fracture has tension forces applied by the muscles or load
bearing
Load applied to bone

30. • The tension band prevents distraction and the force is
converted to compression at the joint
• The tension band functions like a door hinge,
converting displacing forces into beneficial
compressive forces at the joint
JOINT SURFACE
Tension band
Load applied to bone

31. • Wires can be used for tension
band as well
• Ex: Olecranon and patella
• 2 K-wires from tip of olecranon
across fx site into anterior cortex
to maintain initial reduction and
anchor for the tension wire
• Tension wire brought through a
drill hole in the ulna
• Both sides of the tension wire
tightened to ensure even
compression
• Bend down and impact wires
Classic Tension Band of the Olecranon
Figure from: Rockwood and Green’s, 4th ed.

32. Compression Plating
• Reduce & Compress
transverse or oblique
fx’s
– Unable to use lag screw
– Exert compression
across fracture
• Pre-bending plate
• External compression
devices (tensioner)
• Dynamic compression w/
oval holes & eccentric
screw placement in plate

33. Examples- 3.5 mm Plates
• LC-Dynamic
Compression Plate:
– stronger and stiffer
– more difficult to contour.
– usually used in the
treatment radius and ulna
fractures
• Semitubular plates:
– very pliable
– limited strength
– most often used in the
treatment of fibula fractures
Figure from: Rockwood and Green’s, 5th ed.
Figure from: Rockwood and Green’s, 5th ed.

34. Compression
• Fundamental concept critical for primary bone
healing
• Compressing bone fragments decreases the gap
and maintains the bone position even when
physiologic loads are applied to the bone. Thus,
the narrow gap and the stability assist in bone
healing.
• Achieved through lag screw or plating
techniques.

35. Plate Pre-Bending Compression
• Prebent plate
– A small angle is bent into the
plate centered at the fracture
– The plate is applied
– As the prebent plate compresses
to the bone, the plate wants to
straighten and forces opposite
cortex into compression
– Near cortex is compressed via
standard methods
• External devices as shown
• Plate hole design

36. Plate Pre-Bending Compression

37. Screw Driven Compression Device
• Requires a separate drill/screw
hole beyond the plate
• Concept of anatomic reduction
with added stability by
compression to promote primary
bone healing has not changed
• Currently, more commonly used
with indirect fracture reduction
techniques
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

38. Dynamic Compression Plates
• Note the screw holes in the
plate have a slope built into
one side.
• The drill hole can be purposely
placed eccentrically so that when
the head of the screw engages the
plate, the screw and the bone
beneath are driven or compressed
towards the fracture site one
millimeter.
This maneuver can be
performed twice before
compression is maximized.
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

39. Dynamic Compression Plating
• Compression applied
via oval holes and
eccentric drilling
– Plate forces bone to
move as screw
tightened =
compression

40. Lag screw placement
through the plate
• Compression can
be achieved and
rigidity obtained
all with one
construct
• Compression plate
first
• Then lag screw
placed through
plate if fx allows Figure from: Rockwood and Green’s, 5th ed.

41. Locking Plates
• Screw head has threads that
lock into threaded hole in the
plate
• Creates a “fixed angle” at
each hole
• Theoretically eliminates
individual screw failure
• Plate-bone contact not
critical Courtesy AO Archives

42. Locking Plates
• Must have reduction and compression done
prior to using locking screws
– CANNOT PUT CORTICAL SCREW OR LAG
SCREW AFTER LOCKING SCREW

43. Locking Plates
• Increased axial
stability
• It is much less
likely that an
individual screw
will fail
– But, plates can still
break

44. Locking Plates
• Indications:
– Osteopenic bone
– Metaphyseal
fractures with short
articular block
– Bridge plating

45. Intramedullary Nails
• Relative stability
• Intramedullary splint
• Less likely to break with
repetitive loading than
plate
• More likely to be load
sharing (i.e. allow axial
loading of fracture with
weight bearing).
• Secondary bone healing
• Diaphyseal and some
metaphyseal fractures

46. Intramedullary Fixation
• Generally utilizes closed/indirect or
minimally open reduction techniques
• Greater preservation of soft tissues as
compared to ORIF
• IM reaming has been shown to stimulate
fracture healing
• Expanded indications i.e. Reamed IM nail is
acceptable in many open fractures

47. Intramedullary Fixation
• Rotational and axial
stability provided by
interlocking bolts
• Reduction can be
technically difficult in
segmental and
comminuted fractures
• Maintaining reduction
of fractures in close
proximity to
metaphyseal flare may
be difficult

48. • Open segmental
tibia fracture treated
with a reamed,
locked IM Nail.
• Note the use of
multiple proximal
interlocks where
angular control is
more difficult to
maintain due to the
metaphyseal
flare.

49. • Intertrochanteric/
Subtrochanteric fracture
treated with closed IM
Nail
• The goal:
• Restore length,
alignment, and
rotation
• NOT anatomic
reduction
• Without extensive
exposure this fracture
formed abundant callus
by 6 weeks
Valgus is restored...

50. Reduction Techniques…some of
the options
Indirect Methods
• Traction-assistant, fx table,
intraop skeletal traction
• Direct external force i.e.
push on it
• Percutaneous clamps
• Percutaneous K
wires/Schantz pins—
”Joysticks”
• External fixator or distractor
Direct Methods
• Incision with direct fracture
exposure and reduction with
reduction forceps

51. Reduction Techniques
• Over the last 25 years the biggest change
regarding ORIF of fractures has probably
been the increased respect for soft tissues.
• Whatever reduction or fixation technique is
chosen, the surgeon must minimize
periosteal stripping and soft tissue damage.
– EXAMPLE: supraperiosteal plating techniques

52. • Pointed reduction clamps used to reduce a complex distal femur
fracture
• Open surgical approach
• Excellent access to the fracture to place lag screws with the
clamp in place
• Remember, displaced articular fractures require direct exposure
and reduction because anatomic reduction is essential
Direct Reduction Technique

53. • Place clamp over bone and the plate
• Maintain fracture reduction
• Ensure appropriate plate position proximally and distally with
respect to the bone, adjacent joints, and neurovascular structures
• Ensure that the clamp does not scratch the plate, otherwise the
created stress riser will weaken the plate
Reduction Technique - Clamp and Plate
Figure from: Rockwood and Green’s, 5th ed.

54. Percutaneous Plating
• Plating through
modified incisions
– Indirect reduction
techniques
– Limited incision for:
• Passing and positioning
the plate
• Individual screw
placement
– Soft tissue “friendly”

55. • Classic example of
inadequate fixation &
stability
• Narrow, weak plate that is too
short
• Insufficient cortices engaged
with screws through plate
• Gaps left at the fx site
Unavoidable result =
Nonunion Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.
Failure to Apply Concepts

56. Summary
• Respect soft tissues
• Choose appropriate fixation method
• Achieve length, alignment, and rotational
control to permit motion as soon as possible
• Understand the requirements and limitations
of each method of internal fixation
Return to
General/Principles
Index
E-mail OTA
about
Questions/Comments
If you would like to volunteer as an author for
the Resident Slide Project or recommend
updates to any of the following slides, please
send an e-mail to ota@aaos.org