The document discusses the anatomy and biomechanics of facial bone fractures. It begins by describing the structures that make up the skull - the cranial vault, base, and facial skeleton. It then discusses the classification of common midface fractures according to the Le Fort system. The rest of the document details the epidemiology, characteristics, and treatment of various types of facial fractures including nasal, orbital, zygomatic, panfacial and mandibular fractures. Modern treatment primarily involves early open reduction and internal fixation using miniplates and screws.

2. Dr. Ahmed M. Adawy
Professor Emeritus, Dept. Oral & Maxillofacial Surg.
Former Dean, Faculty of Dental Medicine
Al-Azhar University

3. The skull is composed of three principle bony
structures: cranial vault, cranial base, and facial
skeleton. The rigid cranial vault protects the brain
from external injury. The brain rests on cranial base.
This constitutes ‘‘neurocranium’’ (1)

4. Eight bones form the cranial vault: two parietal bones,
two temporal bones, frontal bone, occipital bone,
sphenoidal and ethmoidal bones
Craniofacial skeleton

5. The facial skeleton can be divided for convenience
into three parts; the upper third of facial skeleton
being a part of cranial vault and comprising of frontal
bone, the middle third comprising of central midfacial
bone: the maxilla, the nasoethmoid, and lateral
midfacial bone: zygoma, and the lower third
comprising of rigid bone: mandible, with its condylar
articulation to base of skull (1)

6. Fifteen irregular bones form the facial skeleton:
three singular bones lying in the midline;
mandible, ethmoid, and vomer and six paired
bones occurring bilaterally; maxilla,
inferior nasal concha [turbinate], zygomatic,
palatine, nasal, and lacrimal bones
Facial skeleton

7. The facial skeleton constitutes with the oral cavity and
other associated soft tissues, ‘‘viscerocranium’’. The
facial skeleton is made up of a series of irregular
flattened bones that (with exception of the mandible)
is joined by static articulations called sutures. In
adults, sutures are believed to function primarily as
shock absorbers to dissipate stresses transmitted
through the skull (2)

8. Anatomically, the bones of the cranial vault and the
mandible have a basic structure similar to many other
bones of the skeleton with a strong outer cortex and a
cancellous centre. In contrast, most of the bones of the
midfacial region are comprised only of a thin layer of
cortical bone and exhibit significant variations in their
thickness and composition

9. Thin, fragile mid-facial bones (3)

10. The bone and soft tissues of the midfacial region
are able to absorb the energy from impact forces.
Force to the bone in the elastic range causing the
deformation and after force removal, bone returns
to its previous state, but if the force be greater than
the elasticity of bone, a permanent displacement
occurs and be irreversible. Furthermore, when these
forces exceed the strength of these tissues, a variety
of fractures can occur at this region

11. Load-deformation curve

12. The characteristics of fractures resulting from trauma
are determined by a dynamic factor (given by the
force and energy of the impact) and by a static factor
(given by the anatomic characteristics of the bone
involved). A small impact area results in a localized
fracture, whereas a large impact area leads to more
extensive indirect fractures, because the force is being
transmitted over a larger area of bone (4)

13. According to geometry of face, protruding areas are
most likely to sustain injury. Thus the nasal bones are
most commonly injured, followed by malar bones,
orbital rims, and symphysis of the mandible. The area
of the frontal bone is most resistant to injury. As
fracture occurs energy absorption takes place, thus
protecting the brain from violent deceleration

14. The buttress theory

15. The buttress theory proposes that the midfacial region
is like a framework that is stabilized by horizontal and
vertical buttresses. These buttresses believed to absorb
considerable amount of traumatic energy approaching
the midface region from below. However, the midface
has very low tolerance to impact forces applied from
other directions, with nasal bones exhibiting the least
resistance (5)

16. Biomechanical load distribution along facial buttresses

17. The nasal bones were the most fragile of the facial
bones, with tolerance levels for minimal fracture in
the 25–75 Nm range. The maxilla displayed low
tolerance level in the range of 150–300 Nm. The
relatively fragile zygomatic arch displayed tolerance
levels between 200 and 400 Nm, whereas the body of
the zygoma displayed a higher tolerance level with a
grouping in the 200–650 Nm range. The massive
frontal bone displayed the highest tolerance levels
with grouping between 800 and 1600 Nm

18. Forces (Nm) required to fracture
the facial skeleton (5)

19. Interesting to note that the bite forces in healthy
middle-aged humans averages 520 Nm for males and
340 Nm for females. However, maximal forces have
produced up to the high 700s

20. The buttresses represent areas of relative increased
bone thickness that support both the functional units
and the form of the face in an optimal relation, and
forces directed toward the face are distributed along
these buttresses. Facial buttresses can be classified
into vertical and horizontal buttresses (5)

21. The vertical buttresses are: the nasomaxillary buttress
(connections between the maxilla and nasal bones),
the zygomaticomaxillary buttress (from the maxilla to
the zygomatic region), the pterygomaxillary buttress
(from the maxilla to the pterygoid process) and the
posterior or mandibular buttress (ascending ramus of
the mandible)

22. Vertical buttresses: nasomaxillary, zygomaticomaxillary,
pterygomaxillary, and vertical mandibular

23. The horizontal buttresses include:
(1) frontal bar,
(2) transverse zygomatic buttress,
(3) transverse maxillary buttress,
(4) upper transverse mandibular buttress,
(5) lower transverse mandibular buttress

24. Horizontal buttresses include the frontal, zygomatic,
maxillary and mandibular buttresses

25. The most common causes of maxillofacial trauma
are traffic accidents, injuries from fights, sport
accidents or falls. The combination of traffic accidents
and injuries from fights account for 80% of
maxillofacial fractures (6). The force of impact can be
derived from the equation F = ma (7), where:
Force = mass ( weight) × acceleration ( speed)

26. Egypt leads the Middle East when it comes to road accidents,
with an average of 12,000 people killed annually

27. In such an overcrowded area, interpersonal violence
remains a major problem

28. Around the turn of the 19th into the 20th centuries,
René Le Fort, a French surgeon, conducted a series of
experiments using human cadavers to study facial
bone fractures resulting from blunt trauma. The
impacts included hitting the midface of a whole or
decapitated cadaver with a baseball bat, and hitting the
midface region onto a granite tabletop. He then cut the
body segments open and studied the fractures they had
sustained (8)

29. He concluded that midface fractures occurred through
‘lines’ of inherent weakness in the facial skeletal
structure, producing defined injury patterns. The
fracture patterns were predictable and reproducible,
depending on the site of impact on the midface. He
then formulated a classification system still
extensively used today: the Le Fort classification.
Common to these fractures is involvement of the
pterygoid plates

30. The Le Fort I fracture extends horizontally across the
maxilla above the level of the roots of the teeth,
traversing the lower lateral walls of the pyriform
aperture and the lower nasal septum. It extends
posteriorly across the lateral, medial and posterior
walls of the maxillary sinus and involves the
pterygoid plates. Unique to Le Fort I fracture is the
involvement of the lateral walls of the pyriform
aperture

31. Le Fort I fracture

32. The Le Fort II fracture is pyramidal, with the apex at
the naso-frontal suture. From the apex, the fracture
line extends inferolaterally through the medial wall of
the orbit, orbital floor, inferior orbital rim and through
the zygomatico-maxillary suture. It also extends
posteriorly to the pterygoid plates. Unique to Le Fort
II fractures is involvement of the inferior orbital rim

33. Le Fort II fracture

34. The Le Fort III fracture, also known as cranio-facial
disjunction, is like the Le Fort II, and comprises
dissociation of the naso-frontal suture. However, this
is horizontally oriented, traversing the medial and
lateral walls of the orbits, the zygomatico-frontal
suture and the zygomatic arch. Involvement of the
latter is unique to type III fractures (9)

35. Le Fort III fracture

36. Le Fort fractures. Three-dimensional CT images of an adult skull in frontal and
lateral orientations with color overlays show the osseous facial structures that
are typically affected by type I (red), type II (blue), and type III (yellow)

37. Although useful in describing a midface fracture, Le
Fort’s classification is based on low-velocity trauma,
and does not completely reflect the breadth of high-
velocity fractures encountered in modern practice. In
addition, it underestimate the complexity of facial
fracture patterns, which often include combination of
front-orbital, zygomatic, and nasoethmoidal fractures
with maxillary injury. Moreover, it does not define the
facial skeletal supports or the more severely
comminuted fractures

38. Currently, facial fractures are classified into central
midface fractures, lateral midface fractures and
mandibular fractures. Central midface fractures
include: nasal, nasoethmoidal, orbital wall, maxillary
sinus, Le Fort I, and Le Fort II fractures. Lateral
midface fractures include fractures of the zygomatic-
malar complex, zygomatic arch, and orbital floor
fractures. While Le Fort III fractures are combined
central and lateral midface fractures. In another way,
facial bone fractures are classified as isolated or
complex fractures

39. In a series of multi-trauma patients with over 7,000
facial bone fractures, 24.3% affected the mandible and
71.5% affected the central and lateral midface. Almost
one third of fractures simultaneously affected more
than one area of the face (10)

40. In another study comprising 2,094 cases with facial
bone fractures (11), the most common isolated fracture
site was the nasal bone (37.7%), followed by the
mandible (30%), orbital bones (7.6%), zygoma
(5.7%), maxilla (1.3%) and the frontal bone (0.3%).
The largest group with complex fractures included the
inferior orbital wall and zygomaticomaxillary (14%)

41. Nasal fractures are the most common facial fractures,
accounting for 50% of isolated fractures of the face (12).
Any fracture that involves the nasal bones, septum, or
the nasal process of the maxillary process is considered
a nasal fracture. Symptoms may include bleeding,
swelling, bruising, and an inability to breathe through
the nose. They may be complicated in complex pattern
by other facial fractures

42. Nasal fractures

43. Nasoethmoidal fractures occurred at a frequency of
7%. These fractures most often result from a frontal
blow over the bridge of the nose, and the nasal
pyramid is displaced posteriorly, fracturing the nasal
bones, frontal processes of the maxillae, lacrimal
bones, ethmoid sinuses, cribriform plate, and nasal
septum. In patients with comminution, the bony
segments may spread medially into the nasal cavity,
superiorly to the anterior cranial fossa, and laterally
into the orbit. CSF leaks should be suspected

44. Nasoethmoidal fractures

45. Zygomatic bone fracture is the second most common
midfacial injury, following nasal fracture. A zygomatic
complex fracture is characterized by separation of the
zygoma from its four articulations (frontal, sphenoidal,
temporal, and maxillary). An independent fracture of
the zygomatic arch is termed an isolated zygomatic
arch fracture

46. Zygomatic bone fracture

47. Isolated zygomatic arch fracture

48. Because of the complex anatomy of the region, orbital
fractures are often associated with maxillary, zygomatic
and/or nasal fractures. Isolated orbital fractures can be
classified as ‘blow-out’ or ‘blow-in’. Most blow-out
fractures affect the anteroinferomedial aspect of the orbital
cavity and displace the orbital globe posteromedially and
inferiorly. A significant increase in the volume of the
orbital cavity results in herniation of the orbital floor and
globe to the maxillary sinus. Less often, fracture segments
can herniate upward into the orbit, which is called blow-in
fracture (13)

49. Orbital blow-out fracture

50. Panfacial fractures result from high-energy
mechanisms such as motor vehicle collisions and
gunshot wounds. There are higher chances of cervical
spine and cerebral injuries with these fractures
compared to the other facial fractures. The upper,
middle, and lower faces need to be involved to be
labeled as panfacial fracture (14)

51. Panfacial fractures

52. Clinical examination and computed tomography
imaging are the gold standards in the diagnosis,
planning, and management of facial fractures (15)

53. Significant advances have occurred during the last
two decades in the methods of fixation used for facial
bone fractures, resulting in improved functional and
aesthetic outcomes. Surgical techniques have been
moving away from delayed closed reduction with
internal wires suspension to early open reduction and
internal plate fixation

54. Miniplates and screws for fixation of facial bone fractures

55. The transition from wire osteosynthesis to rigid
internal fixation in craniofacial reconstruction using
different micro or mini-plates and screw systems is
regarded as one of the greatest advances in the field of
maxillofacial surgery. The high degree of ductility in
these microplate screw fixation systems permits an
optimal adaptation to the thin facial bone and provides
three-dimensional stability (16)

56. Interesting to note that plating of fractures began in
1895 when Lane first introduced a metal plate for use
in internal fixation (17). Lane’s plate was eventually
abandoned owing to problems with corrosion. Today,
the use of miniplates provides the principal modality
of treatment for reduction and fixation of displaced
facial fractures. Titanium plates and screws are
considered the “gold standard” to immobilize
displaced fracture segments

57. Lane’s plate. Please note the design and morphology of the plate.
The plate shows a four holes and is retained by mono cortical screws (18)

58. The main limitation with plate fixation is the larger
surgical exposure required and greater profile
(thickness) of the plate beneath the soft tissue. The
conventional fixation of osteosynthesis plates requires
areas of sufficient cortical bone mass to insert screws.
This may be difficult to achieve at sites where the
boney structures is very thin and can cause further
fractures due to the force applied to the fragments (19)

59. The face has relatively little soft tissue to provide
coverage to hardware from the outer surface. It is
therefore not surprising that palpable/ prominent
plates and screws are one of the common
complications in craniofacial procedures. The sliding
of the overlying soft tissue of the face over the
hardware can result in erosion, infection and
subsequent exposure of the fixation devices. Large
size hardware has a larger tendency toward eroding
the overlaying tissue (20)

60. The use of biodegradable implants, glues and adhesive
for fracture fixation has potential to overcome many
of the problems associated with microplate screw
fixation systems. However, to date, substances with
adhesive properties for bone gluing purposes are
limited due to bad biocompatibility, high infection
rates and lack of sufficient adhesive stability (21)

61. The principle aim of these devices and techniques is to
reconstruct the pre-traumatic facial appearance,
including the facial width, projection, and height (22).
The restoration of the normal function of the facial
structures is another aim in facial fracture
management. Modern therapy also mandate the rigid
stabilization of the vertical and horizontal facial
buttress to withstand the forces of mastication

62. Different treatment approaches exist to restore the
facial skeleton using the different facial buttresses as
landmarks. The frontal bar defines the contour of the
upper third of the face. The inferior orbital rim and
malar prominence define the width and projection of
the midface. The maxillary alveolus and piriform
aperture provide the platform for nasal reconstruction

63. Re-establishment of these buttresses is essential for
the maintenance of midface height, width, and
projection. Reconstruction can be done in a “bottom
up & inside out” or “top down & outside in” (23). The
occlusion gives a reference for the width and the
vertical and horizontal planes. Starting from a stable
area to an unstable one is advocated

64. In spite of the advancement in the different types of
technologies and methods of bone fixation, clinicians
continue to experience complications and challenging
reconstruction conditions. Several authors reported an
overall complication rate among craniofacial
procedures between 14% and 22% (24,25). Infection is
one of the most commonly encountered problem, and
is one of the main causes for removal of maxillofacial
internal fixation hardware

65. Nonunion or malunion usually results from failure to
either adequately reduce disparate fracture fragments
or not establishing adequate bone-to-bone contact.
This can result in excessive motion between the bone
segments and cause tissue rupture in the forming
callus and / or hardware failure. Mobility of the bone
fragments can cause numerous problems such as
malocclusion and diplopia (26,27). As such, but even so,
we are still far from ideal

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