Zygomatic Arch Fractures

In 1751, Dupuytren detailed an intraoral and external technique to reduce a medial displaced zygomatic arch. Also described was an approach to the zygomatic arch by way of a plane between the temporalis muscle and deep temporalis fascia.

In 1844, Stroymeyer described the percutaneous traction technique that is still used for repair of zygomatic arch fractures.

In 1927, Gillies was first to mask incisions within the temporal hairline.

Frequency

The zygoma is the second most commonly fractured facial bone, eclipsed in number only by nasal fractures. The vast majority of zygomatic fractures occur in men in their third decade of life.

In 1994, Covington et al reviewed 259 patients with zygoma fractures and found that ZMC fractures occurred in 78.8% of patients, isolated orbital rim fractures occurred in 10.8% of patients, and isolated arch fractures occurred in 10.4% of patients.[5] Of the isolated arch fractures, 59.3% were displaced or comminuted.

Zygoma fractures usually result from high-impact trauma. Leading causes of fractures include assault, motor vehicle or motorcycle accidents, sports injuries, and falls.

A retrospective study by Cohn et al found that out of 218 patients with isolated zygomatic arch fractures, the most common injury source was assault (55%), while accidents were the least common (17.9%).[6]

Arch fractures may result in trismus, flattening of the midface, asymmetry of the malar regions, or a reduction in oral aperture.

In the aforementioned study by Cohn et al, of 218 patients with isolated zygomatic arch fractures, the investigators found that compared with individuals who were managed conservatively, those who underwent surgery were more likely to have presented with zygomatic deformity (97.7% vs 18.4%), paresthesia (29.5% vs 2.9%), and trismus (29.5% vs 6.9%).[6]

Surgical exploration and fracture repair are indicated with a displaced or comminuted fracture, trismus, or significant aesthetic deformity.

Although rarely indicated, emergent surgical repair and decompression are necessary when exophthalmos or signs and symptoms of an orbital apex syndrome are present.

The zygomatic arch is a principal constituent of the midfacial skeleton, bound by the zygomaticotemporal suture line posteriorly and the malar eminence anteriorly.[7, 8]

The arch, in essence, is a rim of bony armor surrounding the temporalis muscle and the coronoid process of the mandible and is the origin of the masseter muscle.

The zygomatic arch is part of the facial subunit known as the zygomaticomaxillary complex (ZMC). The ZMC has 4 bony fusion sites with the skull.

See the image below.

Surgical correction is contraindicated in patients who are medically unstable or unable to tolerate anesthesia.

If alcohol or illicit drug use is suspected, obtain and document serum levels.

As with most surgical patients, appropriate preoperative laboratory tests (eg, complete blood cell count, metabolic panels, activated partial thromboplastin time) and an international normalized ratio are necessary in those with zygomatic arch fracture. Obtain a pregnancy test when clinically warranted.

A chest radiograph may be necessary before proceeding with the repair.

Roentgenograms can be used but are limited by the lack of ability to detect differences in tissue density of less than 10%, making evaluation of soft tissue difficult at best. Standard facial series are the norm and are obtained with varying angulation of the x-ray beam vector. The Caldwell projection allows for visualization of the orbital floor and zygomatic process above the dense petrous pyramids. A submental vertex view affords excellent detail of the zygomatic arches. Anterior-posterior and Waters views reveal much less about the zygomaticomaxillary complex (ZMC) than other planes and are of limited value.

Computed tomography (CT) scans have supplanted radiographs in the evaluation of midfacial trauma and are the current modality of choice.[3] A gray-scale image is created based on various soft tissue linear coefficients that are assigned a particular shade of gray. Direct axial, coronal, or sagittal images can be obtained with proper positioning of the patient. CT scanning without contrast provides views of high-density bone.

Obtain both axial and direct coronal, 1.5- to 2-mm cuts to properly evaluate the orbit. If the patient cannot be manipulated into proper position for direct coronal images, coronal views also may be obtained indirectly by a reformat of thin axial windows. Coronal orbital views provide bone and soft tissue windows, allowing for detailed images of the lateral orbital wall, ZMC, and adjacent soft tissue and bone structures.

Magnetic resonance imaging (MRI) uses a magnetic field and the activity of hydrogen atoms within this field to produce magnificently detailed images of the orbit. MRI enables multiplanar imaging and is excellent for evaluating soft tissue masses and optic nerve pathology.[4] However, although MRI provides exquisite detail of the orbital region, CT scanning remains the imaging modality of choice for evaluation of orbital trauma because of its ability to discern detail of bony structures. Of note, intraocular ferromagnetic foreign bodies can add additional insult to the eye and surrounding structures secondary to the magnetic field of MRI.

An electrocardiogram also may be necessary before proceeding with the repair.

If surgical correction is performed, prescribe prophylactic antimicrobial therapy if a history of endocarditis or other conditions requiring antibiotics is known.

Reconstruction of the zygomatic arch following injury is necessary for restoration of malar symmetry and support for the maxilla and masticatory loads. Repair of the zygomatic arch is usually performed in concert with repair of zygomaticomaxillary complex (ZMC) fracture stabilization. In 1999, Turk et al found that direct repair and plating of the zygomatic arch was not indicated in more than 1500 patients, secondary to spontaneous reduction with repair of other ZMC fracture components.[9] If an aesthetic deformity is the product of an arch fracture or if trismus is present, direct repair and fixation are indicated.[10]

A study by Buller et al found that in cases of isolated zygomatic arch fractures treated with a closed reduction over transbuccal approach, patients with M-shaped fractures had a significantly greater rate of favorable outcomes (83.3%) than did those with differently configured fractures (30.4%).[11]

A study by Hindin et al indicated that in isolated displaced zygomatic arch fractures, the perioperative complication risk is lower and the functional and aesthetic improvements are better with external splint fixation than with an intraoral or temporal approach, with no fixation; coronal flap plate fixation; or no surgery at all.[12]

As with all surgical procedures, successful outcomes are the result of a planned approach that affords excellent exposure of the operative site and of the use of meticulous surgical technique. More specifically, repair of zygomatic arch fractures requires a precise reduction and definitive stabilization to ensure positive outcomes.

Fractures of the zygomatic arch have been approached by various methods.

Direct cutaneous approach

The least invasive approach is the direct cutaneous approach. This entails the placement of a bony hook, hemostat, or suture around the arch. Following this, the surgeon is able to reduce the fracture by applying lateral traction to the arch. Disadvantages include a lack of direct visualization of the bony insult, imprecise reduction, and a lack of fracture stabilization. The only advantage lies in the absence of a surgical incision and resultant cutaneous scarring.

Gillies approach

A 3-cm incision placed 4 cm superior to the zygomatic arch and posterior to the temporal hairline can be fashioned to allow direct access to the arch. This approach (ie, Gillies approach) allows accurate fracture reduction by means of a bimanual technique. The surgeon creates a skin incision, the surgeon carries down a dissection through the superficial temporal fascia and the temporalis muscle fascia (deep temporal fascia). A plane is carried forward, superior to the temporalis muscle to the zygomatic arch.

See the image below.

Once this conduit is created, a periosteal elevator is positioned beneath the zygoma. Lateral traction is placed on the elevator while the surgeon's free hand palpates the fracture site during reduction. Once hemostasis is ensured, the fascia and skin are closed in the usual fashion. Take care to close the wound with all layers reanastomosed to their respective anatomic partners. Advantages of the Gillies approach include a scar camouflaged by the patient's hair, accurate bimanual fracture reduction, and a remote chance of injury to the temporal branch of cranial nerve VII.

Fluroscopy may aid in proper fracture reduction with closed reduction.[13]

Hemicoronal approach

The most invasive approach, offering excellent visualization, is the hemicoronal approach. This method is usually reserved for comminuted arch fractures, and the procedure carries potential for insult to the temporal branch of the facial nerve.

The initial skin incision traverses the scalp from the vertex of the skull to the helical root. Make the scalp incision at least 4 cm behind the hairline. A more posterior placement allows for incision extension behind the ear. This provides added flap mobility.

After the scalp incision and superficial temporal fascia, the surgical plane must remain above the fascia of the temporalis muscle fascia (deep temporal fascia). As the zygoma is approached, a horizontal incision through the temporalis muscle fascia is created 2 cm superior to the zygomatic arch. A subperiosteal dissection permits excellent visualization and protects the facial nerve from inadvertent injury. Once the break has been remedied, the wound is meticulously closed in a layered fashion. Advantages include excellent visualization, accurate fracture reduction, and stabilization. Disadvantages include scarring, possible alopecia, and insult to cranial nerve VII.

Open reduction and internal fixation are warranted with an unstable zygomatic arch, trismus, or diplopia secondary to muscle entrapment.

Following reduction, unstable zygomatic arch fractures may necessitate temporary support to allow for bony union. Several techniques have been described, including percutaneous snaring of the medial aspect of the arch fracture with a wire, which is cinched around a padded external splint. A temporal incision may be used to introduce packing; for instance, an inflated Foley catheter that provides an internal buttress to align the fracture.

Endoscopic approach

An optical cavity is created between the superficial and deep temporal fascias using a periosteal elevator. This blind dissection terminates a the level of the superior orbital rim parallel to the crux of the helix.[14, 15, 3, 16, 17, 18, 19, 20, 21, 22, 23]

The endoscope is introduced and dissection continues to the zygomatic arch. The periosteum of the arch is incised and the arch repaired.

Review and document the patient's medical status and pertinent signs and symptoms pertaining to the injury. Taking photographs of the preoperative appearance of the patient is prudent.

Offer a clear and thorough explanation of the procedure and outline the risks, benefits, and alternatives. Document that such an explanation was provided. Explain to the patient the possibility of a poor cosmetic result and possible asymmetry following surgery. Assessing the patient's expectations helps avoid a situation in which the surgical outcome is successful but leaves the patient is dissatisfied.

A review of imaging is essential for planning the surgical approach and identifying surrounding structures that may serve as anchoring sites for reconstructive materials.

Intravenous antibiotics and dexamethasone (10 mg) are the authors' usual practice for open reduction and internal fixation of facial bones.

As for any surgical procedure, be aware of the patient's overall status as monitored by the anesthesiologist.

At all times, maintain a complete and thorough understanding of the anatomic locale and surrounding vital structures that may be inadvertently insulted. For instance, paresis of orbicularis oculi and zygomaticus muscles can occur when excessive force is placed during posterior arch dissection.

A case-control study by Buller et al reported that in patients with isolated zygomatic arch fractures who underwent closed reduction with a Volkmann hook, those with a variable type of fracture showed a better grade of reduction when intraoperative ultrasonography was employed than did those in whom palpation control was used. The same was not true for patients with an M-shaped fracture.[24]

A prospective study by Czerwinski indicated that C-arm imaging allows accurate realignment in zygoma fracture repair, with a low complication rate. The study involved 20 patients who underwent repair for isolated, displaced, unilateral zygoma fracture, with only one patient demonstrating clinically noteworthy differences between the uninjured and repaired zygomas with regard to projection, width, and height. None of the patients showed a difference in ocular globe projection of more than 2 mm between the two sides of the face. There were no major surgical complications.[25]

Elevate the patient's head 30° in the postanesthesia care area.

To reduce edema, the authors prefer using sterile gauze soaked in iced saline immediately following surgery rather than using ice packs, whose weight and manipulation can be a source of trauma to the surgical site.

A cephalosporin or penicillin-based agent may be prescribed for 1 week postoperatively (eg, cephalexin monohydrate [500 mg tid] 3 times daily for 1 week.

However, a study by Baliga et al suggested that postoperative antibiotics may offer no benefit against infection risk following open reduction and internal fixation of zygomatic or mandibular fracture. In the study, in which 60 patients underwent the procedure, 30 patients received antibiotics before, during, and after surgery, while the rest of the patients received only preoperative and intraoperative antibiotics. The investigators evaluated the patients at 1 and 3 weeks postoperatively, finding that just one patient in each group had developed an infection.[26]

Evaluate all patients on the first postoperative day to assess the wound status, amount of patient discomfort, range of oral motion, edema, and presence of paresthesia or motor weakness. If a hematoma is present, exercise clinical judgment when deciding on management (ie, evacuation vs observation).

The cutaneous sutures may be removed 1 week following surgery if wound healing progresses in a normal fashion.

Paresis of the orbicularis oculi and zygomaticus muscles, as well as sensory deficits secondary to insult of the zygomaticofacial and zygomaticotemporal branches, may be a transient complications.

Although the surgery may be a complete success in the eyes of the surgeon, the patient may view the outcome as unsatisfactory. To minimize this possibility, the surgeon and patient should be in mutual agreement as to the realistic outcome that results from the repair.

As surgeons develop a facility with endoscopic surgical principles and subperiosteal dissection techniques, they can use smaller incisions to reduce and stabilize fractures.

Fixation materials and instruments will continue to evolve and allow for stronger, smaller, and more malleable implants. These advances will permit the surgeon to repair fractures with greater efficiency and less scarring and trauma.