Fractures of the Zygomaticomaxillary Complex



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.








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.






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.

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Oct 7, 2018 | Posted by in OTOLARYNGOLOGY | Comments Off on Fractures of the Zygomaticomaxillary Complex
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