Fractures of the facial skeleton
Fractures of the facial skeleton may be
divided into those in the upper third (above the eyebrows), the middle third
(above the mouth) and the lower third (the mandible). Fractures tend to occur
through points of weakness — the sutures and foramina, and in thin unsupported
hone.
The upper third
The patterns of fracture of the skull tend to
be random but there are points of weakness, mainly involving the frontal sinuses
and the supraorbital ridges.
The middle
third
Fractures of the middle third of the face have
been studied extensively and René Le Fort in 191 1 classified fractures
according to patterns which he created on cadavers using various degrees of
force. The Le Fort classification is used extensively today throughout the
world. While Le Fort classified the fractures from superior to inferior, the
custom today is that the classification runs inferiorly to superiorly (Fig. 38.5).
The
Le Fort I fracture effectively separates the alveolus and palate from
the facial skeleton above. The fracture line runs through points of weakness
from the pyriform aperture, through the lateral and medial wall of the maxillary
sinus running posteriorly to include the lower part of the pterygoid plates.
The
Le Fort II fracture is pyramidal in shape. The fracture involves the orbit,
running through the bridge of the nose, and the ethmoids whose cribriform plate
may be fractured, leading to a dural tear and CSF leak. It continues to the
The
Le Fort III fracture effectively
separates the facial skeleton from the base of the skull — the fracture lines
run high through the nasal bridge, septum and ethmoids, again with the potential
for dural tear and CSF leak, and irregularly through the bones of the orbit to
the frontozygomatic suture. The zygomatic arch fractures, and the facial
skeleton is separated from the bones above at a high level through the lateral
wall of the maxillary sinus and the pterygoid plates. The nasal septum will he
fractured and may be displaced.
These
fractures are seldom confined exactly to this classification and may be
combinations of any of the above.
The zygoma
This is the most common fracture of the middle
third of the face apart from the nose, as the patient turns the cheek to
approaching danger. The fractures occur though points of weakness —
infraorbital margin, the frontozygomatic suture, the zygomatic arch and the
anterior and lateral wall of the maxillary sinus. Tears on the mucosa of the
antrum lead to bleeding from the nose. The infraorbital plate of bone is always
involved to a greater or lesser extent and may cause entrapment of the orbital
contents.
Blow-out
fractures of the orbit
Direct trauma to the globe of the eye may push
it back within the orbit. The globe is a fairly robust structure and as it is
thrust backwards, the pressure increases within the orbit and the weaker plates
of bone may fracture, without necessarily fracturing the bones of the orbital
rim. Such injuries can occur where a pointed object hits the globe of the eye
— for example, a bent elbow of a standing man inadvertently being thrust into
the orbit of a person sitting. A finger deliberately thrust into the eye may
have the same effect. The weakest plate of bone, commonly the infraorbital
plate, ruptures and the orbital contents herniate downwards into the maxillary
antrum. On rebound, as the pressure within the orbit is reduced, the small
fractured pieces of bone may entrap the orbital contents, particularly the
inferior oblique and inferior rectus muscles, leading to failure of the eye to
rotate upwards. Enophthalmos and profound diplopia can follow although
initially both may he concealed by oedema. Anaesthesia over the distribution
of the infraorbital nerve may be an important clue to the blow-out fracture.
Pain is experienced on movements of the eye as the entrapped muscle is
stretched. There may be enophthalmos although this may be masked in the early
stages by oedema. Any fracture that may involve the orbital floor (Le Fort II
and zygomatic bone) must be considered a potential for orbital content
entrapment too.
Fractures of
the mandible
These are usually as a result of blows from
the side or from the front to the lower third of the face. The condylar neck is
the weakest part of the bone and is the most frequent site of fracture (Fig.
38.6) while other fractures tend to occur through un erupted teeth (the impacted
wisdom tooth) or where the roots are long (the canine tooth). Blows from the
side may fracture at the point of injury but, as the force is transmitted to the
base of the skull via the condylar neck, this may fracture first. Blows from the
front may cause fracture in the midline and fractures of both condyles.
Individual sharp blows with a blunt instrument may fracture a segment away from
the mandible. Blows from below may cause the mandible to be thrust upwards
fracturing the alveolus and teeth as they hit their fellows in the maxilla.
Fractures of the mandibular body may also fracture the teeth in the fracture
line.
Much
has been made in the past of the ‘butterfly’ fracture of the mandible. Here
a segment of mandible in the midline