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
General References
Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, 1987.   
Hein U, Pfeiffer KM: Internal Fixation of Small Fractures. Springer-Verlag, New York, 1988.

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
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.)
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 3, 1987.

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
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 3, 1987.

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

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. Primary/Direct Bone Healing Secondary/Indirect Bone Healing
Practically speaking...
Primary/Direct Bone Healing
Secondary/Indirect Bone Healing
Simple fracture patterns
See the fx during surgery and directly reduce and fix with:
Lag screws
Plates and screws
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. Fixation Stability Relative Stability Absolute Stability IM nailing
Ex fix
Bridge plating
Cast
Lag screw/ plate
Compression plate

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

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

14. Functions of Fixation Interfragmentary Compression
Lag Screw
Plate Functions
Neutralization
Buttress
Bridge
Tension Band
Compression
Locking
Intramedullary Nails
Internal splint
Bridge plate fixation
External fixation
External splint
Cast
*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: Cancellous 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. 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 1 2
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

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
Use as sole technique of fixation is limited and advocated only in the fibula and femoral neck and unicondylar fractures.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
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. Lag Screws
Malposition of screw, or neglecting to countersink can lead to a loss of reduction
Ideally lag screw should pass perpendicular to fx
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
Figure from: OTA Resident Course - Olsen

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. Buttress Concepts Order of fixation:
Articular surface compressed with bone forceps and provisionally fixed with k-wires
Bottom 3 cortical screws placed
Provide buttress effect
Top 2 partially-threaded cancellous screws placed
Lag articular surface together
Third screw placed either in lag or normal fashion since articular surface already compressed
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
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. 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
JOINT SURFACE
Tension band
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. Classic Tension Band of the Olecranon
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
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
Alternatively a Verbrugge clamp over a screw can be similarly used to promote compression.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 9, 1987.

36. Plate Pre-Bending Compression
Alternatively a Verbrugge clamp over a screw can be similarly used to promote compression.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 9, 1987.

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
Alternatively a Verbrugge clamp over a screw can be similarly used to promote compression.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 9, 1987.
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.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p.9, 1987.
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
Direct 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
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. Direct Reduction Technique
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

53. Reduction Technique - Clamp and Plate
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
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. Failure to Apply Concepts
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, New York, p. 320, 1987.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

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
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