Concepts of Rigid Fixation in Facial Fractures

1. ‫ه‬‫الر‬ ِ ‫ه‬
‫اَّلل‬ ِ‫م‬ْ‫س‬ِ‫ب‬
‫ي‬ ِ‫ح‬‫ه‬‫الر‬ ِ‫ن‬َ‫م‬ْ‫ح‬
‫م‬

2. ِ‫ان‬َ‫س‬ْ‫ن‬ِ ْ
‫ْل‬ِ‫ل‬ َ
‫س‬ْ‫ی‬َّ‫ل‬ ْ‫ن‬َ‫ا‬
‫ا‬ََ ّٰ ‫ا‬ِ‫ا‬
‫ی‬ٰ‫ع‬َ‫س‬
There is nothing for man except what he strives for
Chapter 53 Surah Najm verse 39

3. Concepts of Rigid Fixation
in Facial Fractures
Presentation by
Dr. Hamza Jawed

4. The concept of Rigid Fixation
• To use hardware in the form of bone plates and screws to absorb part or all
of the functional load of the fracture site preventing any motion across the
fracture
• BASIC DEFINITION
“any form of fixation applied directly to the bones which is strong
enough to prevent interfragmentary motion across the fracture when actively
using the skeletal structure.”

5. • Definition of Non-Rigid Fixation:
“Any form of bone fixation that is not strong (rigid) enough
to prevent interfragmentary motion across the fracture when actively using
the skeletal structure is considered nonrigid”

6. • Definition of Functionally stable Fixation:
nonrigid fixation which is strong enough
to allow active use of the skeleton during the healing phase
but not of sufficient strength to > prevent interfragmentary mobility

7. Origination of the term: RIGID FIXATION
• 1932 > First origination in the orthopedic literature by Key
• 1949 > by Luhr
who described it as
compression of bony fragments as an adjunct to fracture healing
• 1958 > by Bagby and Janes
they published an article on the use of bone plates to achieve
immobilization of the fracture and active compression.

8. • 1973 > Michelet
described the use of miniaturized screws and plates in the reduction
and immobilization of fractures in detail with the experience of
300 cases.
• described

9. Pathways of maxillofacial skeletal fracture
healing
• Fracture healing involves complex set of events
1. Restoration to the pre-injured form
2. Mechanical stability of fractured site > determines the type of healing.

10. Bone Healing Types
• Primary Bone Healing when
a. minimal strain and
b. good anatomic reduction
It is a direct restoration of lamellar bone and only minimal callus is formed.
It is of the two types.
1. Contact Healing.
2. Gap Healing.

11. • In primary bone healing
• Medullary bone portion when placed into apposition will allow
Osteogenic elements and capillary blood supply to traverse the fracture line and
result in longitudinal bone healing with remodeling in about 3 to 4 weeks.
Repair of the cortical bone occurs by growth of capillaries and osteogenic elements
across the fracture lines by cortical tunnels, also known as contact healing.
Cortical bone completely heals after fracture in approximately 16 weeks

12. Contact Healing
1. When there is minimal distance between the fragments and
2. When the fragments are rigidly immobilized
3. Osteoclasts from one fragment “drill” their way into the fracture gap and
into the opposite fragment.
4. Behind osteoclasts come fibrovascular tissue and osteoblasts, which begin
to lay down new bone.
5. With maturation, these become new haversian canals.

13. Contact Healing
Minimal Gap

14. • Gap Healing
A type of primary bone healing when a small gap exists between the rigidly
immobilized fragments, lamellar bone is laid down within the fracture gap.
New haversian canals cross the gap
> no external callus would be found along the outside of the fragments if
they were rigidly immobilized

15. A small Gap
Osteoclasts from one fragment “drilling”
their way into the fracture gap and into
the opposite fragment

16. Types Of Primary Bone Healing

17. Secondary Bone Healing
• When there is increased mechanical strain
1. fractured ends move during the healing process
or
2. when precise anatomic reduction is not achieved.
Movement of the fracture segments result in a large amount of external and
internal callus, which is > body’s way to immobilize the fracture

18. Stages of Secondary Bone Healing
• Secondary bone healing consists of 3 main stages:
1. Inflammation,
2. Repair, and
3. Remodeling

19. 1. Inflammatory Phase
• A hematoma is formed and provides a source of hematopoietic cells
capable of secreting growth factors.
• Fibroblast and mesenchymal cells then migrate to the fracture site
allowing granulation tissue to form around the fractured ends after which
osteoblasts and fibroblasts start to proliferate

20. 2. Repair Phase
• A primary callus will start to form normally within 2 weeks, and
• when the bone ends do not meet > a bridging callus forms.
The size of the callus is inverse to
a. the extent of immobilization and
b. the distance between the fractured ends.

21. 3. The Remodeling Phase
Woven bone > Lamellar Bone
• It begins in the middle of the repair phase continuing long after clinical
union, allowing the remodeling woven bone produced in the repair phase to
become lamellar bone

23. Compression and tension forces
• Frederic Pauwels described the early concepts of load transfer within bone.
• He observed that
a curved tubular structure under axial load always has a
1. Compression side as well as
2. Tension side

25. Advantages of Compression Forces
• Promote rapid healing and a
• Greater resistance to separation
• Does not necessarily promote osteogenesis, but it provides the intimate
apposition and mechanical stability allowing the fractured bone to heal
primarily

26. • Bone is in all times under both the compressive and the tension forces, so
both of the forces should be addressed during rigid fixation.
When one looks at mandible fractures, compressive and tensile forces are
different depending on location.

27. In fractures distal to the canine region,
1. the alveolar region is predominantly under tension
2. the inferior border is under compression.
In fractures anterior to the canine region, the forces are mixed with the
alveolar and inferior border of the mandible having
almost equal tensile and compressive forces during function

29. • more anterior the fracture, the more tendency for torquing of the fragments
to occur, causing mediolateral misalignment of the inferior border.
The directions of forces that are distributed through the anterior mandible
vary with the activity of the mandible.
Classic zones of tension on the superior and compression on the inferior
surfaces of the mandible are not absolute.

30. • Anterior mandible undergoes shearing and torsional (twisting) forces
during functional activities
• This is why most surgeons advocate two points of fixation in the symphysis:
either
1. two bone plates,
2. two lag screws, or
3. possibly one plate or lag screw combined with an arch bar

31. • Examples of rigid fixation schemes for mandibular fracture. A, A large compression plate in
combination with an arch bar for a symphysis fracture (two-point fixation) B, Two lag screws
inserted across a symphysis fracture (two-point fixation). C, Two bone plates for a symphysis
fracture (two-point fixation).

32. Load-bearing vs load-sharing
concepts in rigid fixation
• Load-bearing osteosynthesis:
the plate bears all the forces of function at the
fracture site;
this is accomplished with a
locking reconstruction plate

35. • Load-bearing fixation that uses larger size plates such as reconstruction plates for mandibular
fractures come in profile sizes ranging from 1.5 mm up to 3.0 mm

36. • Load-sharing osteosynthesis
Stability at the fracture site is through
frictional resistance between
the fractured bone ends and the hardware used
to hold the ends together.
Ideally, the bone bears most of the functional loads.

37. Load-sharing fixation options are usually smaller miniplates and come in 1.0 mm or less profile

38. • Load-sharing osteosynthesis includes
1. Lag screw fixation,
2. Compression plating, or
3. Miniplate fixation.

39. Lag Screw Osteosynthesis Technique
• The screw threads engage the cortical bone across the fracture line from
the site of screw insertion.
• The site of insertion of the screw is over-drilled, and
when the screw is tightened, the fractured segments are placed
under compression.
Insertion of at least 2 screws is recommended to
> eliminate the possibility of rotational movement

43. Compression Plates
• They were specifically designed for the maxillofacial region.
• These compression plates used an eccentric compression hole that when
used with a conical screw caused a horizontal translation of the bone relative
to the plate.

44. • The plates are designed so that when placed across a fracture,
the eccentric compression hole
(at least 1 oval bone plate holes is/are drilled eccentrically, that is, away from the fracture)
converge as they are tightened, exerting compression across the fracture.

46. Miniplate Fixation By Michelet and Colleagues
1973
• he advocated the use of
1. small,
2. malleable,
3. noncompressible Vitallium plates.
Without the use of postoperative maxillomandibular fixation.
These plates were placed along the external oblique ridge of the mandible as
a tension band.

47. Modification of the Michelet technique
by
Champy and colleagues (1978)
• He gave ideal line of osteosynthesis for fractures throughout the mandible.
• Small miniplates were used and strict attention was paid to
the tension band principle with placement of these miniplates
as close to areas of maximal tension in the mandible.
Champy’s subsequent results with his technique resulted in
1. an infection rate of 3.8%,
2. malunion rate of the fracture site of 0.5%, and
3. nonunion rate of the fracture site of 0.

48. Materials for rigid fixation
• Many different methods, systems, and materials have been devised for rigid
fixation of maxillofacial fractures

49. Interosseous Wiring
• For interfragmentary compression has been used but
has not been found to be successful without concomitant
maxillomandibular fixation, as it was found that
> wiring alone did not maintain compression adequately.

50. Drawbacks of Wires for Rigid Fixation
• Wires lack
1. adequate rigidity,
2. directional and surface to bone interaction to
> maintain rigidity under functional forces.
• Wires have a small surface area and are
NOT in intimate contact with the bone throughout their length,
resulting in lack of directional control.
• Also, excessive tightening of the bone to increase compression often leads to shearing of
the bone as a result of stress concentration.

51. Plates and Screws
• They function to
1. rigidly support the fracture sites and
2. transfer the functional load to the hardware.
When considering use of hardware for rigid fixation, choices must be made regarding the
proper
 plate length,
 thickness required, and
 the size and type of screws.

52. • Plate length is usually based on the type of fracture being repaired and the
number of screws necessary on either side of the fracture.
• Areas with higher dynamic forces during function, such as the mandible,
require a longer plate.
• Conversely, shorter plates may be adequate in the midface where the
dynamic forces are lower.

53. • In ideal conditions, 3 screws are placed on either side of mandibular fracture
segments to guard against inadequate stabilization and
• 2 screws are placed on either side of fractures in the remaining craniofacial
regions.
• These screws are ideally placed at least several millimeters from the
fracture areas in the non-traumatized bone.

54. • A variety of options are available to the surgeon: differences in
1. Thickness,
2. Internal screw diameter,
3. Titanium grade,
4. Malleability, and
5. Surface area of contact on the bone.

55. How to choose ?
• Generally, the type of rigid fixation is chosen based on
1. The intrinsic forces present at the anatomic site and
2. The bone quality of the fracture segments.
For example, if a young healthy man has a mandible fracture, there is a tendency for
greater bite forces placed on the mandible, and a stronger thicker plate with larger
screws will be used.
Also, if there is poor bone quality with significant
bone atrophy or significant comminution, a similar load-bearing fixation may also be
used

56. • And if zygomatic complex, one can consider small miniplates to
realign the segments, as the amount of forces the plate must withstand is
significantly lower relative to the mandibular region.

58. Locking Plates
• Locking plates allow for the screw head to be locked into the plate,
turning the plate and screw apparatus into an “internal-external fixator”
There are both theoretic and biochemical advantages to the use of this
technique. It is thought that with the use of the locking plate there would be
decreased risk of malocclusion secondary to poor plate contouring and
lower frequency of screw loosening.
However, studies have not shown a clear benefit over nonlocking plates and screws

61. Screw Choice
1. Monocortical and
2. Bicortical screws.
• Monocortical screws only traverse through one of the bony cortices.
When fixating non-mandibular facial fractures, monocortical screws are the
screws of choice.

62. • But when fixating mandibular fractures, bi-cortical screws are sometimes
helpful, as they can ensure that the hardware is able to off-load the force
from the entire width of the mandible.
• When mono-cortical screws are used in mandibular fractures, their limited
bony purchase results in only functionally stable fixation and thus must be
placed along areas of less dynamic tension such as Champy’s lines.

63. Champy’s lines
• These lines run from the angle through the body into the parasymphyseal and
symphysis regions.
• Forces of mastication produce tensional forces on upper border & forces of
compression on lower border.
• Champy put forward the lines where plates & screws have to be placed –
“ideal osteosynthesis lines”
• It corresponds to course of a line of tension at base of the alveolar process.
• Only in symphysis region, 2 plates to neutralize the torsional forces.

65. Screw’s Diameter
• As the screw’s diameter increase, so does the stability against the forces
placed against the fracture site increase.
• In general, smaller screws are effective for simple fractures and
larger-diameter screws are more suited for comminuted or multiple fracture sites.

66. • Also, the larger and heavier a plate is used, the thickness of the screws
increase accordingly.
• Screws can also be used alone without the use of plates to fixate fractures.
• Specialized screws such as lag screws can also be used to stabilize simple
fractures.
• They are placed at a 90-degree angle to the fracture in a plane
parallel to the long axis of the bone.

67. Summary
• Fixation of maxillofacial fractures had not deviated from the techniques
described in 1959 by Adams up until the 1970s.
• Fractures of the upper midface such as the infraorbital rim was repaired
with interosseous wires, whereas the lower midface and mandible were
treated in a closed fashion with intermaxillary fixation and suspension wiring
before rigid fixation of the maxillofacial skeleton.

68. • As rigid fixation plating systems for maxillofacial bony fractures have
improved, increased points of fixation for mid- to upper face fractures have
allowed for improved three-dimensional stability.
• This stability allows preservation of the appropriate facial height, whereas
stronger plates have allowed for reliable reduction of the lower midface and
mandible, preserving the preinjury occlusion.

69. • As rigid fixation systems have evolved in the last 40 years, the size of plates
has decreased to minimize palpability and exposure while maintaining the
same biochemical strength.
• However, the rigid fixation systems are only as good as the surgeons applying them.
• With adherence to basic surgical principles, rigid fixation allows the surgeon
to treat the maxillofacial trauma patient in a way that produces predictable
outcomes with reduced patient morbidity.

71. THANK YOU!