Fractures of the Zygomaticomaxillary Complex
Jason H. Kim
INTRODUCTION
Zygomaticomaxillary complex (ZMC) fractures occur frequently, representing the first or second most common facial fracture, depending on the series reported. They are challenging fractures to manage because they may affect the appearance of the face and compromise orbital and/or masticatory function. Depending on the extent of displacement, comminution, and involvement of adjacent structures, ZMC fractures may require either no invasive intervention, limited approaches with or without fixation, or extensive open treatment and internal fixation (OTIF). These fractures may also occur in the setting of other craniofacial injuries. This chapter will focus on methods to restore form and function following a ZMC fracture.
HISTORY
A history of craniofacial trauma is the sine qua non for ZMC fractures. Assaults and automobile accidents are the most common etiologies. Traumatic impact commonly displaces the zygoma in an inferomedial and posterior direction. Displacement of the zygoma can cause considerable anatomic disruption to the inferior and lateral orbital walls. The ensuing volume change of the orbit can result in enophthalmos, diplopia, orbital dystopia, and malar asymmetry.
It is important to ascertain whether the injury was high or low velocity, as high-velocity injuries more commonly will require OTIF. As with any trauma situation, airway, breathing, and circulation (the primary trauma survey) will take precedence. If able to provide a history, patients may complain of pain around the orbit, decreased sensation over the cheek or teeth, or double vision. Pain associated with ZMC fractures is usually not severe. Any severe orbital pain should alert the examiner to the possibility of ocular trauma or bleeding within the orbit, as these are true emergencies requiring immediate intervention with ophthalmologic consultation. For any patient under consideration for surgery, a history of abnormal bleeding should be obtained in addition to a complete past medical history.
Paramount to the successful reduction of ZMC fractures is the restoration of the anatomy of the orbital complex and zygoma. Inadequate treatment with poor three-dimensional reduction can result in the persistence of enophthalmos and hypophthalmos. In addition, late cosmetic deformities can occur from rotational forces of the masseter muscle displacing the zygoma inferiorly resulting in malar asymmetry. Secondary correction after the occurrence of bone healing is exceptionally difficult, and few cases are amenable to further surgical correction.
Anatomy
The ZMC is a significant component of the facial skeleton with important roles in structure, function, and overall aesthetics. The zygoma is bound by four supporting buttresses and attaches to the frontal bone ( frontozygomatic suture), the maxilla (zygomaticomaxillary suture), the greater wing of the sphenoid (zygomatico-greater wing
of sphenoid suture), and the temporal bone (zygomaticotemporal suture). Each suture line represents one facial buttress with the exception of the zygomaticomaxillary suture, which has two buttresses: a horizontal buttress where the inferior orbital rim/maxilla meet the zygoma and a vertical buttress where the lateral maxillary sinus wall and zygoma meet. Attachment of the masseter muscle to the zygomatic arch provides masticatory capability, while bony structure contributes substantially to the lateral and inferior orbital rim, to the lateral orbital wall, and to the orbital floor.
of sphenoid suture), and the temporal bone (zygomaticotemporal suture). Each suture line represents one facial buttress with the exception of the zygomaticomaxillary suture, which has two buttresses: a horizontal buttress where the inferior orbital rim/maxilla meet the zygoma and a vertical buttress where the lateral maxillary sinus wall and zygoma meet. Attachment of the masseter muscle to the zygomatic arch provides masticatory capability, while bony structure contributes substantially to the lateral and inferior orbital rim, to the lateral orbital wall, and to the orbital floor.
PHYSICAL EXAMINATION
An accurate history and physical examination will help to determine whether a ZMC fracture is present, how severe the fracture is, and if indications exist for repair. Soft tissue injuries should be closed immediately; they may be reopened at the time of fracture repair to provide exposure. Edema sets in within hours of facial trauma. Bony landmarks are often obscured making it difficult to appreciate malar flattening or displacement of the zygomatic arch. It is imperative to firmly palpate the bony surfaces of both sides of the face in order to elicit tenderness, step-offs, and crepitation. In the setting of a ZMC fracture, there may be tenderness and a palpable step-off over the lateral and inferior orbital rims. The arch is most commonly fractured inward, creating discontinuity as the fingers are swept from the lateral orbital rim toward the tragus. To appreciate malar flattening, the examiner should stand behind the semirecumbent patient and press the index finger of each hand over the infraorbital rims. By observing from a top-down or submental vertex viewpoint, the examiner can appreciate depression of the fractured side. Facial sensation is very often decreased in a V2 distribution due to fracture site involvement of the infraorbital nerve along the orbital floor or at the level of the foramen.
Intraoral examination may reveal ecchymosis in the maxillary gingivobuccal sulcus. Malocclusion is not an expected finding in isolated ZMC fractures. However, some patients may associate numbness of the teeth with malocclusion. Trismus, if present, is indicative of temporalis muscle or coronoid process impingement on the fractured zygomatic arch and is an indication for reduction of the fracture.
It is likewise imperative to examine the eyes for the presence of gaze restriction, enophthalmos, diplopia, globe injury, and loss of visual acuity. In the awake patient, extraocular movements may be elicited in the standard fashion. If gaze restriction is present, it will usually be from edema of the orbital contents, or from inferior or medial rectus muscle entrapment. Forced duction testing is the most accurate method for diagnosing entrapment and differentiating it from orbital edema. This is not a diagnosis made from CT imaging. Enophthalmos is present when the volume of the bony orbit is expanded relative to its contents. ZMC fractures may result in posterolateral displacement of the lateral orbital wall and disruption of the orbital floor. This expansion creates the appearance of a “sunken” eye. The supratarsal crease of the upper lid may become deepened with a hollowed appearance. Enophthalmos following trauma is an indication for repair. Diplopia should be assessed in each cardinal direction of gaze. If present, diplopia must be categorized as monocular or binocular, as the former may be indicative of lens dislocation, retinal tear or detachment, or other ocular pathology requiring ophthalmology consultation. Injury to the globe is not uncommon and, if suspected, must be addressed prior to repair of the fracture. With any bony orbital injury, subconjunctival hemorrhage and chemosis will likely be present (Fig. 50.1). Visual acuity should be assessed and documented using a Snellen chart.
Indications for Ophthalmology Consultation
Suspected globe injury
Monocular diplopia
Loss of visual acuity
Severe orbital pain
FIGURE 50.1 Right eye with subconjunctival hemorrhage indicative of orbital trauma. Subconjunctival blood will remain bright red long after trauma due to the ease of oxygen diffusion across the thin conjunctival membrane.
Proptosis/concern for retrobulbar hematoma
Severely swollen eyelids
INDICATIONS
Displacement of the zygoma with anatomic disruption to the inferior and lateral orbital walls creating significant volume change of the orbit
Bony fragments impinging on the optic nerve or musculature
Hypophthalmos
Enophthalmos
Orbital dystopia
Muscular entrapment with resultant diplopia
Malar asymmetry
Orbital rim step-off
Trismus
CONTRAINDICATIONS
Often, patients with such injuries may also present with a constellation of other injuries requiring attention prior to treatment of ZMC fractures. In such circumstances, the patient must commonly have general medical, anesthesia and neurologic (C-spine) clearance prior to entering the operating theater. In circumstances with suspected or confirmed injury to the globe, consultation must be obtained with an ophthalmologist prior to surgical management.
PREOPERATIVE PLANNING
In the case of multisystem trauma, repair of facial fractures is often delayed by management of life-threatening injuries. It is often advantageous to allow 3 to 5 days for facial edema to subside. Reexamination is then necessary as clinical findings may change. In particular, restriction of gaze may resolve as edema subsides. Systemic steroids may also be given to reduce edema prior to surgery. Prophylactic antibiotics are routinely administered when there is communication between the orbit and the sinus cavities. Patients are reminded not to blow the nose and to sneeze with the mouth open to prevent orbital emphysema. Cervical spine clearance prior to surgery is extremely helpful to avoid bulky cervical collars or immobilization procedures at the time of operation.
Patient consent must be obtained for OTIF of facial fractures via multiple approaches, including sublabial, transcutaneous, and transconjunctival with or without lateral canthotomy and cantholysis. Risks include bleeding, infection, anesthetic complications, malunion or nonunion of fractures, hardware extrusion, scar, development of late enophthalmos, eyelid malposition, damage to the eye including loss of vision, diplopia, gaze restriction, postoperative healing complications, need for additional procedures, and poor cosmetic outcome in spite of optimal treatment.
Imaging
High-resolution CT scanning of the maxillofacial bones with triplanar reconstruction is required for planning of operative treatment of ZMC fractures. We do not routinely obtain plain films. CT images are assessed for displacement of the fracture lines, bony comminution, and involvement of the orbital floor. These three measures will dictate the approaches needed and the extent of rigid fixation required.
CT images: (1) nondisplaced ZMC fracture, nonoperative (Fig. 50.2); (2) arch fracture (Fig. 50.3A-C); and (3) severely displaced fracture (Fig. 50.4A-C).
SURGICAL TECHNIQUE
The preferred surgical technique will depend on the extent of the ZMC fracture. For isolated arch fractures, I will describe the Gilles approach. The technique for OTIF of more complex ZMC fractures is also detailed.
Gilles Approach
With the patient in the prone position, general endotracheal anesthesia is induced. The table is rotated 180 degrees away, and corneal shields with Lacri-Lube ointment are placed to protect the eyes. Examination of the
zygomatic arch under anesthesia is performed to assess for mobility of fracture segments. The temporal tuft on the fractured side is shaved with surgical clippers in a 2- × 2-cm square over a point 2 cm superior to the root of the helix. The face is prepped including the ears and both temporal regions. The head is draped with a blue towel to cover the hair.
zygomatic arch under anesthesia is performed to assess for mobility of fracture segments. The temporal tuft on the fractured side is shaved with surgical clippers in a 2- × 2-cm square over a point 2 cm superior to the root of the helix. The face is prepped including the ears and both temporal regions. The head is draped with a blue towel to cover the hair.
 FIGURE 50.2 Left-sided minimally displaced ZMC fracture not requiring OTIF (arrow). |
After surgical pause to verify patient, site, and procedure, the superficial temporal artery is palpated. The bifurcation should be at or below the shaved area. It is important that the artery and accompanying vein are not violated during the procedure, as this may add time and cause significant bleeding. 1% lidocaine with 1:100,000 epinephrine is injected in the skin prior to incision with a 15-blade knife. Dissection is carried down through the skin and temporoparietal fascia to the deep temporal fascia, which should appear white and glistening. Ideally, the approach is just superior to the bifurcation of this fascia around the temporal adipose tissue pad. The knife blade is used to make a 1-cm incision in the deep temporal fascia, exposing fibers of the temporal is muscle. A Freer elevator is used to bluntly dissect in an anteroinferior direction toward the zygoma, opening a pocket for placement of the bone elevator. If dissection is carried too far medially, the elevator may perforate the
temporalis muscle and track medial to the coronoid process of the mandible. Lateral dissection may place the Freer elevator over the zygomatic arch, jeopardizing the temporal branch of the facial nerve. Once a sufficient tract has been developed, an elevator may be inserted. I prefer to use the Dingman or Cobb elevator. Measure the length of the elevator against the cheek and place the thumb of the dominant hand at the distal extent of the instrument adjacent to the incision. Insert the elevator in the pocket, and it should advance smoothly into position. Place the fingers of the nondominant hand over the arch. With a movement that is simultaneously twisting and levering, rock the arch back into position. An audible crack may be heard as the fracture is reduced.
temporalis muscle and track medial to the coronoid process of the mandible. Lateral dissection may place the Freer elevator over the zygomatic arch, jeopardizing the temporal branch of the facial nerve. Once a sufficient tract has been developed, an elevator may be inserted. I prefer to use the Dingman or Cobb elevator. Measure the length of the elevator against the cheek and place the thumb of the dominant hand at the distal extent of the instrument adjacent to the incision. Insert the elevator in the pocket, and it should advance smoothly into position. Place the fingers of the nondominant hand over the arch. With a movement that is simultaneously twisting and levering, rock the arch back into position. An audible crack may be heard as the fracture is reduced.
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