Rigid internal fixation involves directly visualizing and fixing fractured bone segments using hardware like plates, screws, and wires. It provides sufficient rigidity to withstand forces from chewing. Rigid internal fixation aims to keep fractured bone ends together, immobilize the fracture site, and promote primary bone healing. Dynamic compression plates use an inclined plane and compression screws to draw bone fragments together across a fracture for rigid fixation. Miniplates provide semi-rigid fixation that allows some movement between bone fragments. They are commonly used for mandibular fractures.

1. RIGID INTERNAL
FIXATION

2. DIRECT FIXATION
(INTERNAL FIXATION)
 The surgical method of fixation of
the fracture segments by direct
visualization using hardware
 Such as -
 Wires
 Plates
 Screw

3. • What is osteosynthesis?
Osteosynthesis is the reduction and internal
fixation of a bone fracture with implantable devices
that are usually made of metal.
surgical procedure with an open or per cutaneous
approach to the fractured bone.
Osteosynthesis aims
• keep the fractured bone ends together
• immobilize the fracture site
• rigidly immobilized - intramembranous
ossification

4. What is Rigid internal fixation?
direct method of fracture fixation where the hardware or
implant used for fixation provides sufficient rigidity for the
jawbone to withstand masticatory stresses.
• Avoids immobilization by MMF
• Does not allow micromotion of fracture segments
• Absolute stability

6. INDICATIONS for internal fixation
Trauma- facial bone fracture
Orthognathic surgery
Reconstruction of craniofacial deformities
Reconstruction of bony defects 2 ͦ to
ablative tumour surgery.
Augmentation of atrophic mandible in the
elderly

7. Varios concepts of Fixation
 Rigid internal fixation & Non rigid fixation
 Load-bearing & load-sharing fixation
 Compression & Non compression plates
osteosynthesis
 Locking & Non locking plate-screw system

8. Rigid internal fixation
• rely on two point fixation—a
stabilizing unit, such as a bone plate
at the inferior border, and a tension
band, such as a miniplate or arch bar
superior to that.
• rigid internal fixation with minimal
gap between the bone segments
allows for primary bone healing
• Fractures with a significant gap or
interfragmentary motion,heal by
secondary intention
semi rigid internal fixation
• allows for movement
between the bone fragments
across a fracture line.
• Do not prevent
interfragmentary
movement.
• Champy method for the
fixation of angle fractures-
functionally stable

9. • LOAD-BEARING FIXATION
is a device that is of sufficient
strength and rigidity that it can bear the
entire load applied to the mandible during
functional activities
• comminuted fractures of the mandible
• those fractures where there is very little
bony interface because of atrophy,
• those injuries that have resulted in a loss
of a portion of the mandible (defect
fractures)
LOAD-SHARING FIXATION is any form of
internal fixation that is of insufficient stability
to bear all of the functional loads..
requires solid bony fragments on each side of the
fracture that can bear some of the functional load
Fractures that can be stabilized adequately with
load-sharing fixation devices are simple linear
fractures,and constitute the majority of
mandibular
fractures
Eg;-2.0 mm miniplating systems

10. Techniques of RIF
The goal of the AO or ASIF is
rigid internal fixation with primary bone healing, even
under functional loading.
To achieve this goal, four basic principles must be achieved
1. Accurate reduction of the bone fragments
2. stable fixation of the fragments
3. preservation of the adjacent blood supply, and
4. Early functional mobilization.

11. RIGID FIXATION
 COMPRESSION PLATES –
 DYNAMIC COMPRESSION PLATE(DCP)
 ECCENTRIC DYANAMIC COMPRESSION
PLATE (EDCP)
 LAG SCREW
 ANCHORAG LAG SCREW
 RECONSTRUCTION PLATE
 THORP
 LOCKING PLATE
 LOCKING RECONSTRUCTION PLATE

12. COMPRESSION OSTEOSYNTHESIS
Luhr helped advance the principles of compression and
dynamic compression, but it wasn’t until 1977 that he
developed these techniques to the maxillofacial skeleton.
Spiessl later popularized dynamic compression bone
plating of the mandible using Arbeitsgemeinschaft für
Osteosynthesefragen-Association for the Study of Internal
Fixation (AO-ASIF) techniques.
From Luhr and Spiessl’s work, eccentric dynamic
compression plating was developed and adapted for
craniomaxillofacial trauma use, but lost popularity due to its
highly technique sensitive nature and no proven benefits
over other modern fixation methods.

13. IF compression is used on both sides of the fracture, a total
of 1.6 mm of bone movement may be achieved (0.8 mm on
each side)

14. COMPRESSION OSTEOSYNTHESIS
Based on AO/ ASIF principles
design of the dynamic compression
plate is based on a screw head that,
when tightened, slides down an
inclined plane within the plate.
The compression hole is elongated in
a direction parallel to the axis of the
Plate.

15.  Algower et al 1970
 This is the spherical gliding
principle.
 Screw head is turned it glides in a
section of inclined sphere
 Fragments grasped by the screw is
moved horizontally & guided further
towards the fracture gap
 Two types of screws- compression screw
and static screw
DYNAMIC COMPRESSION PLATES
(DCP)
Inclined plane within the hole in the plate. As screw is
tightened, it moves down the inclined plane, causing
the underlying bone to translate toward the fracture
site.

16. Pitfall: gap at lingual cortex
If the plate is not slightly
overbent, the buccal
cortex will be well
aligned but a gap
remains at the lingual
cortex
As compression
screws are
tightened, the
slightly overbent
plate closes the
lingual gap
The plate must be overbent
slightly to close the lingual
cortex. It must be overbent in
all areas of the mandible where
compression plating is used.
Plate overbent
approximately 1mm and
not touching buccal cortex.
Gap in lingual cortex present.

18.  Properties of plate
1. Plate has inclined plane in the hole proximal to the
fracture
2. The highest portion of the inclined plane lies on the
outer aspect of hole
3. Two types of screws- compression screw and static
screw
4. Minimum two screws on each side
5. Unfavorable fracture requires longer plates
with more screws
6. Order of fixation-
 1 & 2 proximal to the fracture
on eitherside (compression
screws)
 3 & 4 the holes next to the
compression screwson either
side(passive screws)
 5 and more distal to the passive screws

19.  Indication
 Nonoblique fracture with good bony apposition
after reduction
 Contraindications
 Severely oblique fracture
 Comminuted fracture
 Fracture with bone loss
 Disadvantages
 Require precise adaptation
 If used on oblique fractures, the fragments slide
over one another
 Maladapted plate in anterior mandible creates
widening of mandible
 Technique sensitive
 Ideally should be placed on tension zone, but
due to anatomic reasons the plate is placed
on the inferior border
 In fracture with good reduction and no bone loss,
causes stripping of screws and bone splintering
adjacent to fracture

20. Tension band

21. ECCENTRIC DYNAMIC COMPRESSION
PLATE(EDCP)
In 1973, Schmoker,
Niederdellmann and Schilli simultaneously
developed a plate incorporating the principle of
eccentric dynamic compression.
The design of this plate represents method of
producing compression at the superior border of
the fractured mandible.
The design of this plate is similar to the DCP in that the
inner holes are designed to produce compression
across the fracture site

22. ECCENTRIC DYNAMIC COMPRESSION PLATE
(EDCP)
 Compression osteosynthesis
 Compressive force through
centric(axial) & eccentric at outermost
holes
 8mm wide
 centre screws are inserted first
 Inner hole-transverse- Compress
fracture at basal border
 Outer hole-oblique- rotate along
the inner screw & compress the
fracture

23.  Used in situations where tension band application
is not possible
 Presence of impacted third molar with angle
fracture
 Edentulous mandibular fracture
 Avulsion of bone from fracture site
 Plate design
Outer holes have inclined planes oblique in
relation to long axis of plate.
ECCENTRIC DYNAMIC
COMPRESSION PLATE
(EDCP)

24. LAG SCREW
 Defined as the stable union of two bone
fragments under pressure with the help
of screws inserted in lag fashion.
 Compress fracture fragments without the use
of bone plate
 Two sound bony cortices are required -
- Shares the loads with the bone
 Oblique fracture
 Principle- a screw that glides through the
cortex of one fragment and engages the cortex
of the opposite fragment with its thread, draws
the fragments together and compresses them
when tightened.
 Gliding hole in one segment, thread hole
in other

25.  Avoid shearing of the
fragments
 The screw holes for lag
screws should be drilled
perpendicular to the
fracture line &
perpendicular to the
bone surface
 Contraindication -
comminuted fractures

26. ADVANTAGES
 Absolute rigid fixation
 Less hardware
 More cost effective
 Insertion -quicker and easier
DISADVANTAGES
 Loosening of screw
 Damage to bone
 Mobility of fragments
 Incidence of pain
 Infection

27. ANCHOR LAG SCREW
 The fixation system used included
2 mm titanium lag screws of sizes
25 mm, 27 mm and 30 mm and 3
mm titanium bio-concave
washer.
 Post surgery evaluation indicated
no loss of bone contact around the
screw head, bone resorption &
loosening of lag screw
 Bio-concave washer provides easy
loading of lag screw. Holding up the
farthest fragment on resorption

28. NON COMPRESSION FIXATION
OSTEOSYNTHESIS
 Indication
Oblique fracture
Comminuted fracture
Loss of bone fragments in
fracture
Questionable postoperative
complication
Nonatrophic edentulous
fracture
1. RECONSTRUCTION
PLATES
2. LOCKING
RECONSTRUCTION
PLATES
3. THORP

29. RECONSTRUCTION PLATES
 Load bearing
 They are thickest plate can
be used without tension band
 Plate can be bended by 15˚without
distortion of plate holes 8mm in
width 2.7 mm and 3.2mm thick
 Straight plate with 6-24 holes
mandible angle plate 4,6,8 holes
 reconstruction plate is strong enough
to overcome the functional load as
well as to counteract the
masticatory forces & provide primary
stability

30.  The plate must be long enough
so that there can be a minimum
of three or preferably four
screws on each side of the
fracture.
 The screws adjacent to the
fracture should be at least 7 mm
away from the fracture line.
 2.0 mm plate with bicortical
screw used in conjunction
with lag screws or miniplates
 Defect fractures can be
treated(comminuted, mandibular
angle)

31. RECONSTRUCTION PLATES
 DISADVANTAGES
o Screws in these large plates may cause
another fracture upon placement
o Screws can fail by stripping the bone
o Inflammation
o Bony necrosis
o Injury to the inferior alveolar nerve

32. LOCKING RECONSTRUCTION PLATES
 Useful in securing plates that cannot be perfectly
adapted to fractures or if bone quality is poor.
Locking screws are double-threaded
the head of the screw has an additional larger
diameter thread that secures into the thread pattern
of the plate hole.
• result is a rigid frame construct with high mechanical
stability (internal external fixator)

34. Conventional plate system
essential to contour the plate
precisely to the bone surface
When using conventional plate and
screws the plate must be precisely
adapted to the bone, otherwise the
tightening of the screws will lead to
a primary loss of reduction.
Locking plate system
the plate does not have to be
precisely adapted to the
bone. When tightening the
screw will not cause a primary
loss of reduction

35. ADVANTAGES
Stable fixation
Precise plate adaptation not mandatory
More viable periosteum as plate does not
compress bone
Minimises complications with loose screws
Loosening of the screw will not occur.
Decreased incidence of inflammation &
infection

36. THORP
 Developed to fulfill the requirement of total
oseointegration and long term functional stability
 Types of plate
1. Pre-bent
2. Straight
3. Attachment
with TMJ
prosthesis
(TITANIUM HOLLOW OSSEOINTEGRATED RECONSTRUCTION PLATE)

37.  Plate thickness 3 mm
 Reconstruction plate is notched between
the 4.0 mm- diameter holes
 Toprevent deformation of the plate holes
when the plate is bent
 Plastic insert in the bolts for retention
 Expansion bolt is applied to the
head screw
 Plates can be easily bent in any direction
without deformation of the holes
 Spread the strain over a greater length
on bending and reduced possibility of
plate failure

38.  Screws ( two types)
1.Titanium plasma-coated, perforated hollow
screw
2. Titanium full-body screw
 Cylindrical screw head
 Screw diameter
- 4.5mm for hollow screw
- 3.5 to 4mm for full body screw
 Thread depth 0.5mm
 Implant volume low for
osseointegration
 Screw surface coated with 0.04mm with
argon titanium plasma spray
 Pitch- 1.25- 1.50 mm

39. Advantages
 Prevents focal ischemia, bone
necrosis, screw loosening and plate
mobility
 Promotes osseointegration
 Reducing the of infection & malunion
Disadvantages
 Plate removal is difficult
• Plate fracture
 Skin perforation
 Mucosal dehiscence

40. SEMI RIGID FIXATION
MONOCORTICAL MINIPLATE
OSTEOSYNTHESIS

41. Mechanical Stress on mandible under
Function
The force of the masseter, medial
pterygoid, and temporalis muscle
results in upward and forward vector
of force on the posterior aspect of the
mandible.
The suprahyoid musculature places a
downward and posterior force on the
anterior portion of the mandible.
With the pterygomasseteric sling
functioning as a point of fulcrum, the
superior border of the angle/posterior
mandible is placed under tension
while the inferior border is placed
under compression

42. Beam mechanics dictates that the
mandible is a class III lever, with
the condyle being the fulcrum, the
muscles of mastication acting as
the applied force, and bite load
acting as the
resistance .
This rationale applies to one side of
the mandible at a time, but as a
horse shoe shaped bone, the
mandible is more than a simple
class III lever.

43. When loaded, the mandible exhibits
maximum tension at the superior border and
maximum compression at the inferior border .
This is a gradient and, between the zones of
tension and compression, lies a neutral zone
in which opposite forces total zero.
In this model, it would be mechanically
advantageous to apply rigid fixation
hardware along the zone of tension, or
superior border.
Biologically, this is complicated by the
presence of teeth, thin cortical bone, and thin
overlying soft tissue.

44.  MITCHEL et al 1960s, CHAMPY et al
1976 -- Non compression miniplates
 Used in all types of mandibular
fracture
 Available with self tapping mono-
cortical screws;
 It can be placed in areas adjacent to
tooth roots
 Provide three- dimensional stability
 There are two screws on either sides
of the fracture resists the
anteroposterior & rotary movement
of fracture segments
MINIPLATE FIXATION SYSTEM

45. Principles of fixation
• Usually one plate with 4
cortices of fixation are
required for adequate
immobilisation
• Anterior to mental foramen, 2
levels of fixation are required
to overcome torsional forces
• Unfavourable fractures usually
require 2 levels of fixation for
stability
• Fixation along Champy’s line
allows better fixation due to
the strong buttress structure

46. MINIPLATE
 0.7- 0.9mm
thickness
 Length 2-9 cms
with 4, 6, 8 to16-
hole plates
 Diameter of hole
2.1mm 30˚ beveled

47. MINIPLATE
Types :
 Straight
 Curved
 L type
 Y shape
 Double T plates
 Mini orbital plates
 The connection bar between
plate holes facilitate contouring
of plates in all 3 dimension
and optimal adaptation of
plates

48. MINIPLATE
 Plate lies flat to the bone across the
fracture line
 Screws
 Self cutting bone screw
 2mm in diameter
 Length 5-15mm
 1.6mm diameter thread core
 Flat screw head (2.8mm
diameter)
 Single slit
 Centric hole to accommodate a
screw driver blade

49. ADVANTAGES
 Reduced size,
 Smaller incisions
 Less tissue dissection,
 Less palpable,
 Reduced necessity of removal
DISADVANTAGES
 Infection
 Dehiscence of wound, exposure of plate
 Functional restriction recommended
 Cannot be used in comminuted fractures

50.  Muscular forces on midface
skeleton are
much less
 Thinner and malleable
microplates used of size 1.0mm
& 1.3mm
 Low profile- advantageous in
areas of minimum
overlying soft tissue
 Application through smaller
incisions in
aesthetically sensitive areas
 Can be used for fixation of
bones in Cranium , orbital
rim, zygomatic process,
anterior maxilla and NOE
complex
 Provide limited stability
MICROPLATE FIXATION SYSTEM

51. 3-D PLATE OSTESYNTHESIS
 Developed by Farmand(1992)
 The plates are not 3 dimensional, but
hold the fracture fragments rigidly by
resisting the forces in three
dimensions, namely, shearing,
bending, and torsional forces.
It is geometrically closed
quadrangular plate
The stability is gained over a
defined surface area and is
achievedby its configuration
and not by its thickness or length.

52. BIORESORBABLE PLATES
 Metallic plates- growth
restriction and plate
translocation
 Bio resorbable materials
used for rigid fixation
 POLYGLYCOLIC ACID
 POLYLACTIC ACID
 POLYDIOXANONE
 The plates used will resorb
over a period ranging from 2
to 4 years

53. Advantages:
 Provides the proper strength when
necessary and then
harmlessly degrades over
time.
 No need for an additional
removal operation.
 Reduce the total treatment &
rehabilitation time of the
patient.
Disadvantages
 Long resorption time
 Less stable than conventional
systems
 No radiopacity
 Infection / inflammatory response

54. PENCILE BONE PLATE
 A monocortical 2.0 mm titanium, 8 or
10- hole hardware
 The two proximal holes are
spherical sliding holes that allow
minor compression even with
monocortical screws
 Treatment of atrophic
mandibular fractures, by an
intra-oral approach
 patients with mandibular heights
ranging from ‘‘10 mm or less’’ to 20
mm
 Carries properties of a miniplate with
an improved stability

55.  Rigid fixation of the
craniomaxillofacial skeleton,
Michael J yaremchuk
 Oral n maxillofacial trauma- fonseca
 Textbook of oral and maxillofacial
surgery-Rajiv M Borle
 https://www.aofoundation.org
REFERENCES