Rene Le Fort introduced a classification of midfacial fractures on the basis of cadaver experiments he performed in the early part of the 20th century (6). He noted that fractures tend to occur at characteristic locations, which correspond with relatively weak areas of the facial skeleton.

Le Fort Level I fractures are transverse fractures separating the maxillary alveolus from the rest of the midfacial skeleton (Fig. 81.3).

These injuries generally result from anterior force directed at the lower midface. The NM and ZM buttresses are disrupted (7). The fracture line then extends transversely through the maxillary sinus and nasal septum and posteriorly across the pyramidal process of the palatine bone and pterygoid processes of the sphenoid bone (2).

Le Fort Level II fractures create a pyramidal NM fragment separate from the upper craniofacial skeleton. They result from either direct anterior force against the midface or inferior impact at the mandibular symphysis transmitted to the midface via the dentoalveolar segments of the mandible. Once again the NM and ZM buttresses are disrupted, this time more superiorly than the Le Forte I level. The fracture line extends from the nasal root via the lacrimal bone and medial orbital wall, then anteriorly along the orbital floor to the infraorbital canal. From this point, the fracture line follows the ZM suture to anterolateral maxillary wall. Posteriorly, the fracture line passes across the infratemporal surface of the maxilla through the lower pterygoid plates (7, 8).

Le Fort Level III fractures, which result in complete separation of facial skeleton from the skull base, are less common. They usually result from anterior force directed obliquely to the plane of the vertical buttresses (1). The vertical buttresses are disrupted at their superiormost extent. The fracture line extends through the root of the nose, across the lacrimal bone and medial orbital wall, across the orbital floor to the inferior orbital fissure. From this point, one fracture line traverses the lateral orbital wall as it approaches the frontozygomatic suture; a second line passes over the back of the maxilla to the lower pterygoid plates. An additional fracture line through the zygomatic arch completes the craniofacial dysjunction (8, 7).

In clinical practice, the patterns of maxillary fractures encountered are rarely as orderly as the above suggests. Le Fort’s original work demonstrates that he was certainly not unaware of this. The level I to III classification scheme is a distillation of some of his most significant experimental observations. In his experiments, and most definitely in real-life trauma, force is delivered unevenly to each side of the face, at varying angles, and at variable locations. The resulting fractures may be asymmetric from one side of the face to the other (i.e., Le Fort II on the left, Le Fort III on the right), may combine with other fractures to create a more complex pattern (e.g., a Le Fort II fracture and a zygomaticomaxillary complex (ZMC) fracture on the same side of the face constituting a “complex” Le Fort III fracture), or may be maxillary fractures not described by the classification at all.

Anterior forces localized between the nose and malar prominence may produce anterior maxillary wall fractures. Significant force delivered to the lower anterior midface, in addition to generating the classic fracture patterns described by Le Fort, may less commonly cause fractures
of the palate. While they may occur in isolation, palatal fractures tend to accompany extensive facial injuries (9). Most often, the palate is fractured in a sagittal fashion, in a paramedian plane (see Fig. 81.11). Fractures in a number of other orientations and locations are also possible (10). Clinical indicators of palatal fractures include palatal lacerations, lip lacerations that extend into the gingivolabial sulcus, maxillary tooth loss, and malocclusion.

Palatal fractures, and in particular those oriented sagittally, alter the width of the maxilla and permit the rotation of the maxillary dentoalveolar segments. One of the fundamentals in management of severe facial fractures is the intraoperative restoration of normal maxillomandibular occlusion, with anatomic reduction of fractures following from this basis. Palatal fractures, by complicating the restoration of occlusion, can confound this strategy if not appropriately addressed first (10, 11).

Various terms are used to describe fractures involving the zygoma and its articulating bones. These include malar fractures (12), zygoma or zygomatic fractures (13), ZMC fractures (14), tripod fractures (15), tetrapod fractures, trimalar fractures, zygomatico-orbital fractures (16), and orbitozygomatic fractures (17). All of these terms emphasize certain salient features of this type of injury. For example, the term “tripod” underscores the observation that blunt force to the zygoma tends to disrupt not the zygoma itself, but rather, its three superficial articulations, to the frontal, maxillary, and temporal bones; the intact body of the zygoma has a tripod-like appearance (Fig. 81.4). The terms “zygomatico-orbital fracture” and “orbitozygomatic fracture” stress that because it forms portions of the lateral and inferior orbit, fractures that involve the zygoma are necessarily also orbital fractures. The most important point for the surgeon-in-training to understand is that all of the terms refer to the same injury. Henceforth within this chapter, the term ZMC fracture is used for uniformity.

ZMC fractures generally result from blunt trauma to the malar eminence, the most prominent feature of the lateral midface. They are the second most common facial fracture, after nasal fractures (18). Routinely, they involve disruption of the projections of the zygoma. The severity of ZMC fractures seems most related to the force and velocity of impact (14). In the most severe injuries, the sturdy zygoma itself may be fractured.

A distinctive clinical feature of ZMC fractures is orbital injuries that differ somewhat from those found in isolated orbital trauma. In a typical orbital floor blowout fracture, orbital volume expands; the extent of expansion predicts the likelihood of enophthalmos and diplopia, and the need for surgical repair. In ZMC fractures, the typical inward and medial displacement of the zygoma often results in a decrease in orbital volume (19). Therefore, acute enophthalmos is rarely seen at the time of presentation of a ZMC fracture. The need for floor exploration/repair in ZMC fractures must also take into account the effect that reduction will have on orbital volume.

Another common clinical feature of ZMC fractures is facial numbness and paresthesia. This is caused by damage to the infraorbital nerve (V₂) at its exit from the midportion of the inferior orbital rim, which lies directly within one of the fracture lines. These symptoms are present in as many as 90% of ZMC fracture patients at presentation (20). The symptoms resolve spontaneously in many, but not all, patients after disimpaction of the fragments.

The zygomatic arch is most frequently disrupted as a component of a ZMC fracture (21). Less common, and distinct from this type of injury, is the isolated zygomatic arch fracture. Isolated arch fractures result from a direct lateral force to the arch, most frequently the result of a motor vehicle accident or fisticuffs (21).

Several fracture patterns may be seen in isolated arch injuries. The most common pattern is two mobile fragments of arch resulting from a total of three fractures. In this pattern, the fragments are displaced medially, in a v configuration (Fig. 81.5).

Patients with isolated arch injuries, particularly those with the characteristic v pattern, will have a palpable, and frequently visible, deformity of the lateral midface (Fig. 81.6). This finding is often accompanied by a degree of trismus, resulting from the impingement of the fracture segments on the underlying coronoid process of the mandible or the temporalis muscle.