The document discusses the basic principles of internal fixation for fractures. It describes the two types of bone healing - primary healing which requires rigid fixation, and secondary healing which involves callus formation. It provides examples of techniques for rigid fixation using plates and screws versus semi-rigid fixation using wires or casts that allow callus formation. Key concepts covered include the use of compression through lag screws or dynamic compression plates to promote primary healing.

1. Basic Principles and
Techniques of Internal Fixation
of Fractures
Dan Horwitz, MD

2. Biology of Bone Healing
• Rigid Fixation - bone heals directly to bone
• Nonrigid fixation or immobilization - the
body forms a fibrous matrix which
transitions to cartilage, calcified cartilage,
disorganized woven bone, and finally
organized lamellar bone.
THE SIMPLE VERSION...

3. Biology of Bone Healing
• Primary bone healing
– Requires rigid internal fixation and intimate
cortical contact
– Cannot tolerate soft tissue interposition
– Relies on Haversian remodeling with bridging
of small gaps by osteocytes

4. Biology of Bone Healing
• Secondary Bone Healing = CALLUS
– Divided into stages
• Inflammatory Stage 5-14 days
• Repair Stage
– Soft Callus Stage
– Hard Callus Stage
• Remodeling Stage 3-24 mo

5. Practically speaking...
• Plates and screws = primary bone healing
• Cast = callus formation
• IM Rods = primarily secondary bone
healing/callus - depends on location of
fracture, size of nail, quality of bone…
• Small wire/tension band = usually callus
formation unless bone quality is excellent in
which case rigidity may be achieved.

6. 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...

7. Fracture Patterns
• Lateral bending produces a transverse fracture pattern
while torsional or twisting forces produce oblique or
spiral fracture patterns.
• Understanding these patterns and the inherent
stability or instability of each type is important in
choosing the most appropriate method of fixation
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

8. Clinical Examples

9. • Callus formation and
consolidation in a distal
third tibia fracture
treated in a cast.
• The central defect
is asymptomatic and
produces no long term
problems.
Casting
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

10. Rigid Internal Fixation:
Proximal Humerus
• Fixation is achieved by lagging
the head to a laterally
stabilized plate.
• The plate is necessary because
the lateral cortex of the
proximal humerus is unlikely
to be adequate to support the
lag screws alone.
• Extensive soft tissue dissection
is required for this construct.
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

11. •The humerus represents rigid
internal fixation with a broad
4.5 DC plate.
•The ulna has 2 lag screws
combined with a classic tension
band on the olecranon.
•The tension band represents
stable but not rigid fixation
Combined Fixation Techniques
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

12. Combined techniques for rigid
fixation of a distal humerus fracture
• The dual plates provide
stability in two planes at
the metaphyseal
diaphyseal junction
• The lag screw provides
reduction and stability at
the articular surface.
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

13. Semi -Rigid Fixation:
Proximal Humerus Fracture
• This technique utilizes small K wire fixation after impaction of
the shaft into the head and is supplemented by a modified tension
band laterally.
• Healing in this situation is achieved by both primary bone healing
as well as callus formation.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

14. Indications and Benefits of
Internal Fixation
• Displaced intraarticular fracture
• Axial or angulatory instability which cannot
be controlled by closed methods
• Open fracture
• Malreduction/interposed soft tissue
• Multiple trauma
• Early functional recovery
MULTIPLE REASONS EXIST BEYOND THESE...

15. Methods of Internal Fixation
• Screws - Design
• Plates - Design
• Lag screw/Interfragmentary screws - COMPRESSION
• Dynamic compression plating - COMPRESSION
• Neutralization plate
• Buttress plate
• Reduction techniques
• IM Nailing

16. Screws
• Cortical screws:
– greater surface area of
exposed thread for any given
length
– better hold in cortical bone
• Cancellous screws:
– core diameter is less
– the threads are spaced farther
apart
– lag effect option with partially
threaded screws
– theoretically allows better
fixation in soft
cancellous bone.
Figure from: Rockwood and Green’s, 5th
ed.

17. Examples- 3.5 mm Plates
• LC-Dynamic
Compression Plate:
– stronger
– 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.

18. Examples- 3.5 mm Plates
• The plates on the right are
thin, pliable and often used
in the distal radius.
• Those on the are left also
fairly thin and are designed
for subcutaneous
application in sites such as
the distal, medial tibia.
Figure from: Rockwood and Green’s, 5th
ed.

19. Example: A Reconstruction Plate
• Both small frag
(3.5mm) and large
frag (4.5mm) sizes
• fairly good strength
• multiplanar
contourability
• often used in
acetabular fractures
and about the elbow
Figure from: Rockwood and Green’s, 5th
ed.

20. Compression
• Fundamental concept critical for primary bone
healing
• Compressing bone fragments decreases the gap
the bone must bridge creating stability by
preventing fracture components from moving in
relation to each other.
• Achieved through lag screw or plating
techniques.

21. 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.

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

23. 1
2
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.
•Compression Lag Screws
• Provide stability through compression
between bony fragments
• Step One: drill a pilot hole equal in
size to the outer diameter of the screw
selected generally perpendicular to the
fracture
• Step Two: Place of a guide sleeve into
the pilot hole and drilling of the far
cortex with a drill equal to the core
diameter of the screw

24. COMPRESSION - LAG SCREWS
• The screw glides through
the near cortex and only
engages the far side.
• When the screw engages the
far cortex it compresses it
against the near cortex.
• This technique must usually
be supplemented by
additional internal or
external fixation.
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

25. Compression - Lag Screws
• A functional lag screw between fragments on the left - note the
near cortex has been drilled to the outer diameter of the screw and
permits compression
• The screw on the right has not been drilled to the outer diameter on
the near cortex and the result is lack of compression and gap at the
fracture.
Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

26. Combined Plating and Lag
Screw
• Compression can be
achieved and rigidity
obtained all with one
construct.
Figure from: Rockwood and Green’s, 5th
ed.

27. •A classic example of
inadequate fixation and
stability.
•This fracture was fixed with
a narrow, weak plate,
insufficient cortices were
engaged,and gaps were left
at the fracture site.
•The unavoidable result is
a nonunion.
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

28. Buttress and Antiglide Concepts
• In this model the white plate is secured by three black
screws distal to the red fracture line.
• The fracture is oriented such that displacement from
axial loading requires the proximal portion to move
to the left.
• The plate acts as a buttress against the
proximal portion, prevents it from “sliding”
and in effect prevents displacement from
an axial load.
• If this concept is applied to an intraarticular
fracture component it is usually referred to as a
buttress plate, and when applied to a diaphyseal
fracture it is usually referred to as an antiglide
plate.

29. • The bottom 3 cortical screws
provide the basis for the buttress
effect.
• The top 3 screws are in effect
interfragmentary screws and the 2
top screws are lag screws because
they are only partially threaded.
• Underbending the plate can be
advantageous in that it can increase
the force with which the plate
pushes against the proximal
fragment.
• NOTE: screws are placed from
distal to proximal maximizing the
buttress action and aiding in
reduction.
Buttress Plate
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

30. The Neutralization Plate
• The two lag screws
provide compression
and initial stability.
• The plate bridges the
fracture and protects
the screws from
bending and torsional
loads.
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.

31. Reduction Techniques…some of
the options
• Traction
• Direct external force i.e. push on it
• Percutaneous clamps - INDIRECT METHOD
• Percutaneous K wires - INDIRECT METHOD
• Minimal incision, debridement of hematoma
• Incision and direct fracture exposure and
reduction- DIRECT METHOD

32. 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 should attempt to
minimize periosteal stripping and soft tissue
damage.
– EXAMPLE: supraperiosteal plating techniques

33. • The use of a pointed reduction clamps to reduce a complex
distal femur fracture pattern.
• Excellent access to the fracture to place lag screws with
the clamp in place
• Can be done open or percutaneously, as long as the
neurovascular structures are respected.
Reduction Technique

34. • 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.

35. JOINT SURFACE
Tension band
Tension Band Theory
• The concept here is that a “band” of fixation at a distance from the
articular surface can provide reduction and compressive forces at
the joint.
• The fracture has bending forces applied by the musculature and
these forces have a component which is perpendicular to the
joint/cortical surface.

36. • Since the tension band prevents distraction at the
cortex the force is converted to compression at the
joint.
• The tension band itself essentially functions
like a door hinge, converting displacing forces into
beneficial compressive forces at the joint.
JOINT SURFACE
Tension band

37. • 2 K-wires up the ulnar shaft
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.

38. Intramedullary Fixation
• Generally utilizes closed 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

39. Intramedullary Fixation
• Rotational and axial stability provided by
interlocking screws
• Reduction can be technically difficult in
segmental, comminuted fractures
• Fractures in close proximity to metaphyseal
flare may be difficult to control

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

41. • Subtroch fracture
treated with closed
IM Nail.
• The goal here is to
restore alignment
and rotation, not to
achieve anatomic
reduction.
• Without extensive
exposure this
fracture formed
abundant callous
by 6 weeks.
Valgus is restored...

42. Summary
• Respect soft tissues
• Choose appropriate fixation method
• Achieve stability, length, and rotational
control to permit motion as soon as possible
• Understand the limitations and requirements
of methods of internal fixation
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