Complete Information Synthesized (Summary)

Maxillofacial injuries are commonly encountered in the practice of emergency medicine. More than 50% of patients with these injuries have multisystem trauma that requires coordinated management between emergency physicians and surgical specialists in oral and maxillofacial surgery, otolaryngology, plastic surgery, ophthalmology, and trauma surgery.

Trauma to the maxillofacial anatomy mandates special attention. Contained within the face are systems that control specialized functions including seeing, hearing, smelling, breathing, eating, and talking. Also, the vital structures in the head and neck region are intimately associated. Lastly, the psychological impact of disfigurement can be devastating.

The maxillofacial region is divided into 3 parts.

• The upper face: Here, fractures involve the frontal bone and frontal sinus.
• The midface: The midface is divided into upper and lower parts. The upper midface is made up by the zygoma, nasal bones, ethmoid bone, and non-tooth–bearing segment of the maxillary bone. This is where maxillary LeFort II and LeFort III fractures occur and/or where fractures of the nasal bones, nasoethmoidal complex (NOE) or zygomaticomaxillary complex (ZMC), and the orbital floor occur. The lower midface is composed of the maxillary alveolus, teeth, and the palate and is where LeFort I fractures occur.
• The lower face: This is composed of the mandible, where fractures can occur

More than 3 million facial injuries occur in the United States each year. Most are secondary to assaults and motor vehicle accidents. Information about the causes of facial fractures depends on the country and location of the trauma center; therefore, reported statistics vary widely.

Etiology of MI

Facial trauma in an urban setting is most often caused by assaults, followed by motor vehicle and industrial accidents.

The nasal bones, mandible, and the zygoma are the most commonly fractured bones during assaults. Facial trauma in the community setting is most often due to motor vehicle accidents, followed by assaults and recreational activities. Motor vehicle accidents produce fractures that often involve the midface, especially in patients who were not wearing their seatbelts. Other important causes of facial trauma include penetrating trauma (knife and gunshot wounds), domestic violence, and the abuse of children and elderly persons.

Pathophysiology 

The kinetic energy present in a moving object is a function of the mass multiplied by the square of its velocity. The dispersion of this kinetic energy during deceleration produces the force that results in injury. High-impact and low-impact forces are defined as greater or lesser than 50 times the force of gravity. These parameters impact on the resultant injury because the amount of force required to cause damage to facial bones differs regionally. The supraorbital rim, the maxilla and the mandible (symphysis and angle), and frontal bones require a high-impact force to be damaged. A low-impact force is all that is required to damage the zygoma and nasal bone.

• Frontal bone fractures: These result from a severe blow to the forehead. The anterior and/or posterior table of the frontal sinus may be involved. Assume a dural tear is present if the posterior wall of the frontal sinus is fractured. The nasofrontal duct often is disrupted.
• Orbital floor fractures: Injury to the orbital floor can result in an isolated fracture or can be accompanied by a medial wall fracture. When a force strikes the globe or orbital rim, the intraorbital pressure increases with transmission of this force and damages the weakest aspects of the orbit, the floor and medial wall. Herniation of the orbital contents into the maxillary sinus is possible. The incidence of ocular injury is high, but globe rupture is rare.
• Nasal fractures: These are the result of the forces transmitted during direct trauma.
• Nasoethmoidal fractures (NOE): These extend from the nose to the ethmoid bones and can result in damage to the medial canthus, lacrimal apparatus, or nasofrontal duct. They also can result in a dural tear at the cribriform plate.
• Zygomatic arch fractures: A direct blow to the zygomatic arch can result in an isolated fracture involving the zygomaticotemporal suture.
• Zygomaticomaxillary complex fractures (ZMC): These fractures result from direct trauma. Fracture lines extend through zygomaticotemporal, zygomaticofrontal, and zygomaticomaxillary sutures and the articulation with the greater wing of the sphenoid bone. The fracture lines usually extend through the infraorbital foramen and orbital floor. Concurrent ocular injuries are common.
• Maxillary fractures: These are classified as Le Fort I, II, or III
  

  • LeFort I fracture is a horizontal maxillary fracture across the inferior aspect of the maxilla and separates the alveolar process containing the maxillary teeth and hard palate from the rest of the maxilla. The fracture extends through the lower third of the septum and includes the medial and lateral maxillary sinus walls extending into the palatine bones and pterygoid plates.
  • LeFort II fracture is a pyramidal fracture starting at the nasal bone and extending through the ethmoid and lacrimal bones; downward through the zygomaticomaxillary suture; continuing posteriorly and laterally through the maxilla, below the zygoma; and into the pterygoid plates.
  • LeFort III fracture or craniofacial dysjunction is a separation of all of the facial bones from the cranial base with simultaneous fracture of the zygoma, maxilla, and nasal bones. The fracture line extends posterolaterally through ethmoid bones, orbits, and pterygomaxillary suture into the sphenopalatine fossa. See the image below.
    
• Mandibular fractures: These can occur in multiple locations secondary to the U-shape of the jaw and the weak condylar neck. Fractures often occur bilaterally at sites apart from the site of direct trauma.
• Alveolar fractures: These can occur in isolation from a direct low-energy force or can result from extension of the fracture line through the alveolar portion of the maxilla or mandible.
• Panfacial fractures: These usually are secondary to a high-energy mechanism resulting in injury to the upper face, midface, and lower face. These fractures must be composed of at least 3 of the possible 4 facial units in order to be labeled panfacial. See the image below.