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 medial part of the infraorbital rim, through the infraorbital foramen and through the infraorbital fissure. The orbital floor is always involved. It continues posteriorly through the lateral wall of the maxillary antrum at a higher level than the Le Fort I to the pterygoid plates at the back. The nasal septum is displaced and lateral walls of the nose are fractured.

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 is detached from the rest of the mandible with fractures in the canine regions. The segment of bone takes on the appear­ance of a butterfly, and this will include the anterior insertion of the tongue (geniohyoid and genioglossus). Conceptually, the tongue may fall back and occlude the airway. First, the fracture is extremely rare, and second, the patient can still control the tongue, if allowed to by a good nursing position (see above).