Zygomaticomaxillary Complex Fractures

See Clinical.

Frequency

A much higher percentage of zygomaticomaxillary complex (ZMC) fractures occur in males (80%) than in females (20%). Incidence of ZMC fractures peaks in persons aged 20-30 years. Women who have been domestically abused are more likely to suffer ZMC fractures and orbital blow-out fractures,[19] while mandible fractures are more common when the female victim did not know the assailant.

 

The most common causes of zygomaticomaxillary complex (ZMC) fractures include personal altercations, falls, motor vehicle accidents, and sports injuries.[20] Other associated facial fractures occur in 25% of patients who sustain ZMC fractures.[21]

A study by Brucoli et al using a multicenter systematic European database reported assaults to be the predominant cause of ZMC fractures, with falls being the second most frequent etiology.[22]

See Relevant Anatomy for a discussion of the impact of zygomaticomaxillary complex (ZMC) fractures on other facial structures.

Classification

Many authors have devised classification schemes for zygomaticomaxillary complex (ZMC) fractures.[21, 23, 13] Zingg (1992) separates these injuries into types A, B, and C.[24] Type A injuries are isolated to one component of the tetrapod structure, including the zygomatic arch (type A1), the lateral orbital wall (type A2), and the inferior orbital rim (type A3). Type B fractures involve all 4 buttresses (ie, classic tetrapod fracture). Type C injuries are complex fractures with comminution of the zygomatic bone itself. These classification schemes are of little clinical significance; however, they are helpful in research and physician communication.

Type A fractures are relatively uncommon. Type B and C fractures account for 62% of ZMC injuries.[21] Types B and C fractures most commonly occur at the zygomaticomaxillary and zygomaticotemporal buttresses. The zygomaticofrontal buttress is the strongest of the 4 ZMC buttresses. Significant disruption at this site usually implies a high velocity injury with comminution in other areas. The weakest bone of the ZMC complex is the orbital floor. Type A3, B, and C injuries result in orbital floor disruption, which places the orbital contents at risk.

The initial evaluation of facial trauma patients is focused on areas that can result in the greatest morbidity. Airway control and hemodynamic stability are the primary concerns. Next, spinal cord injury must be ruled out by a thorough clinical and/or radiological examination.

Finally, any overt globe injury should be evaluated. After the patient has been stabilized, a thorough history can be taken and physical examination can be performed. A complete head and neck examination will reveal most bony or soft tissue injuries. When zygomaticomaxillary complex (ZMC) fractures are identified, an ophthalmologic consultation should be obtained.

The most common symptoms associated with ZMC fractures include pain, edema, and ecchymosis of the cheek and eyelids. Malar flattening and palpable periorbital step-offs, often occur. The traumatic force and pull of the masseter muscle may result in medial, inferior, and posterior rotation of the zygoma.[25] Trismus (ie, reduced jaw mobility) may result from compression of the zygomatic arch on the temporalis muscle and coronoid process. Orbital floor disruption can result in subcutaneous emphysema. Infraorbital nerve injury may result in anesthesia or paresthesias of the cheek, nose, upper lip, and lower eyelid.

Jelks (1987) reported a 14-40% incidence of significant intraocular injury in patients with ZMC fractures that involved the orbital floor.[26] For this reason, preoperative ophthalmology consultation is essential in patients with orbital floor injuries. Disruption of the bony orbit often results in expansion of the orbital volume and herniation of orbital contents. Inferior (hypophthalmos) and posterior (enophthalmos) globe displacement both occur.

Extraocular muscle contusion or entrapment may result in diplopia. Upward gaze diplopia is most common, secondary to entrapment of the inferior rectus muscle and soft tissue surrounding it. However, any of the extraocular muscles may be involved. Comparing forced-duction tests on each eye can help to identify the specific site of muscle entrapment. This study is much easier to perform under general anesthesia. Evaluation of unanesthetized patients is often difficult because of poor patient cooperation.

Compression of the orbital contents occurs less frequently. These injuries result in decreased orbital volume and displacement of the globe both superiorly (hyperophthalmos) and anteriorly (exophthalmos). These injuries are associated with an increased risk of optic nerve injury and visual loss. Physical findings such as severe conjunctival hemorrhage or hyphema are suggestive of direct globe injury, rupture, and visual loss.

Surgical intervention is indicated in patients with injuries that result in a significant cosmetic or functional deformity, such as the following:

• Visual compromise: Significant exophthalmos and orbital apex syndrome are indications for emergent surgical decompression.

• Extraocular muscle dysfunction: Muscle contusion, local tissue edema, or extraocular muscle entrapment and strangulation can cause extraocular muscle dysfunction. Edema and contusion usually resolve without long-term sequelae; however, muscle entrapment does not resolve. Muscle necrosis with long-term diplopia can occur if entrapped muscle is not released expediently.

• Globe displacement: Enophthalmos or hypophthalmos following acute injury becomes more pronounced with resolution of edema. Acute orbital dystopia requires surgical intervention.

• Significant orbital floor disruption: Large orbital floor fractures result in long-term enophthalmos and hypophthalmos. The definition of a "significant orbital floor injury" varies among authors. However, injuries encompassing 25-50% of the orbital floor have a higher risk of long-term enophthalmos. In these patients, orbital exploration with surgical repair should be considered.

• Displaced or comminuted fractures: These injuries generally result in cosmetic deformity and require surgical repair.

The malar eminence is the most prominent portion of the zygomaticomaxillary complex (ZMC) and is located approximately 2 cm inferior to the lateral canthus. The malar eminence corresponds to the central portion of the ZMC. From this central position, 4 bony attachments to the skull are evident, namely, a superior attachment to the frontal bone (frontozygomatic suture line), a medial attachment to the maxilla (zygomaticomaxillary suture line), a lateral attachment to the temporal bone (zygomaticotemporal suture line), and a deep attachment to the greater wing of the sphenoid bone (zygomaticosphenoidal suture line).[27] Some authors describe the zygomaticomaxillary and zygomaticosphenoidal suture lines as a single unit. Using this definition, ZMC fractures are called tripod fractures. However, the term tetrapod fracture is a more accurate description because 4 suture lines are disrupted.

The term ZMC fracture describes a spectrum of injuries that includes nondisplaced fractures, fractures displaced at an isolated buttress, and severely comminuted fractures with bone loss. Information about the degree and severity of the overall injury can be extrapolated from the location of the fractures.

The frontozygomatic and zygomaticosphenoidal buttresses are very strong. Isolated injuries in these areas are uncommon. When displaced fractures are noted, a high velocity injury with other associated fractures is likely.

The inferior orbital rim is a common location for displaced and comminuted fractures. These injuries can be isolated, but they are often associated with orbital floor fractures. The zygomaticomaxillary buttress is commonly disrupted and associated with V2 paresthesias. Isolated injuries often occur in the zygomatic arch because of its length and unprotected location.

Contraindications to surgical repair of zygomaticomaxillary complex (ZMC) fractures include medical instability and globe injuries. Orbital exploration in the presence of a hyphema or ruptured globe can result in exacerbation of the injury.

A study by van Hout et al of 153 unilateral ZMC fractures indicated that in cases of comminuted fractures, treatment outcomes were worse than those for either incomplete or tetrapod fractures. The investigators reported that the rate of secondary correction for ZMC malreduction, secondary orbital floor reconstruction, and functional correction of diplopia via correction of the extraocular muscles was greater in the comminuted fractures.[28]

Traditional facial radiographs have limited usefulness in the diagnosis of zygomaticomaxillary complex (ZMC) fractures. The submental-vertex view offers excellent resolution of the zygomatic arches; however, the Townes, anteroposterior, and Waters views offer much less information. Gross bony disruption of the orbital rim or opacification of the maxillary sinus can be diagnosed; however, the dense temporal bone makes subtle findings difficult. Even if a facial fracture is diagnosed using plain radiographs, a CT scan usually is needed to determine the extent of the injury.[29]

CT scans, depicted in the images below, are considered the criterion standard for radiologic diagnosis of ZMC fractures.[5, 6]

The CT scan helps the physician make a more accurate preoperative diagnosis and guides decisions about the operative treatment. Patients with traumatic injuries frequently require CT scans of the brain to evaluate intracranial injuries. If significant clinical suspicion of a facial fracture exists, the images can be continued through the facial bones. Modern helical scanners can reformat thin cut (1- to 1.5-mm) axial images into coronal and sagittal cuts with acceptable resolution to avoid neck flexion and extension.

Visual acuity: Any injury resulting in significant disruption of the bony orbit requires an ophthalmologic evaluation. This evaluation allows dilated funduscopic examination for retinal detachment from the trauma or hyphema. Either of these findings likely delays immediate surgical fracture reduction until the intraorbital injuries are managed.

Extraocular motion: Function of the extraocular muscles is evaluated with concentration on potential entrapment of the inferior or medial rectus muscle by an orbital floor or medial orbital wall fracture, respectively.

Infraorbital nerve dysfunction: The presence or absence of skin sensation to light touch should be documented, accounting for the function of the infraorbital nerve.

Forced-duction tests: Forced-duction testing can be used to determine the presence of mechanical restriction of globe motion. This test must be performed bilaterally to compare the uninjured and injured sides. It is generally performed with the patient under general anesthesia because most patients cannot relax enough to allow accurate testing.

Unfortunately, the diagnostic studies available to differentiate muscle contusion from muscle entrapment (eg, thin-cut CT scans, forced-duction testing) are not 100% accurate. These tests are quite specific when muscle entrapment is observed; however, they often are not sensitive enough to rule out entrapment in subtle cases. Therefore, diagnostic surgical exploration must be considered for patients with significant orbital disruption and extraocular muscle dysfunction, even if gross muscle entrapment cannot be identified clearly. Transmaxillary endoscopic evaluation of the orbital floor is a relatively new technique that can also be used to assess the integrity or the orbital floor.

Axial preoperative CT scans do not clearly define the extent of orbital blowout fractures. Patients with facial traumatic injuries with suspected cervical spinal cord injuries cannot hyperextend their head for coronal CT scan, and thin cut reconstructions are not always available. Consequently, the degree of orbital floor disruption is not known until the time of surgery. Before the surgical endoscope, evaluation of the orbital floor necessitated a lid or rim incision to evaluate the extent of disruption. In such cases, the risk of orbital exploration must be weighed against the risk of missing an occult injury to the orbital floor and orbital contents. The exacerbation of an orbital floor injury after reduction of the zygomaticomaxillary complex should also be considered. A large lateral movement of the ZMC may actually widen a small orbital floor disruption requiring an orbital exploration for diagnosis and treatment.

The endoscope can be used to evaluate the orbital floor (ie, the roof to the maxillary sinus) by passing it through preexisting fractures in the face of the maxilla. When gross disruption of the anterior maxillary face is not present, a 4-mm osteotome is used to open a small maxillary sinusotomy, taking care not to injure the infraorbital. A Kerrison can then be inserted into the sinusotomy and an antrostomy 1.5 cm by 2.0 cm can be performed (ie, Caldwell-Luc sinusotomy). When the endoscope is then inserted into the maxillary sinus, the integrity of the orbital floor can be evaluated from below.[30, 31]

Gentle pressure on the globe (ie, pulse test) exaggerates any significant prolapse of the orbital contents into the maxillary sinus. After the evaluation is complete, the sublabial incision is closed in the traditional fashion. Repair of the Caldwell Luc sinusotomy is not necessary.

This technique involves a significant learning curve, and surgeons are encouraged to continue using a standard approach to these injuries to confirm what is noted on endoscopy. Once experience is ample, the surgeon can confidently identify smaller, inconsequential orbital floor defects and avoid a formal orbital exploration.

Intraoperative radiologic assessment of the reduction of these fractures has been documented using a C-arm[32] or intraoperative CT scanning Advantages include immediate visualization of the fracture reduction and necessary revision without waking the patient from anesthesia. Disadvantages included increased radiation dosages and costs that may be prohibitive.

Patients with a nondisplaced or minimally displaced zygomaticomaxillary complex (ZMC) fracture and normal findings on ophthalmologic examination can be treated conservatively. Medical management includes a soft diet, analgesia, and close follow-up care.

The ultimate goal in treating zygomaticomaxillary complex (ZMC) fractures is to obtain an accurate stable reduction while minimizing external scars and functional deformity.[33] These goals are accomplished more easily several days after the injury, when much of the tissue edema has resolved and any residual deformity can be appreciated more readily.

After induction of general endotracheal anesthesia, the surgeon should evaluate any existing lacerations that may be used for fracture reduction or application of plates and screws. Common surgical approaches to the ZMC buttresses include sublabial, lateral orbit, lower eyelid, and scalp incisions. These incisions should be used in a hierarchical fashion starting with the sublabial incision.

The sublabial incision is well camouflaged and is associated with minimal morbidity, including mild trigeminal paresthesias. It can be used to reduce and plate the zygomaticomaxillary buttress (and, at times, the inferior orbital rim). Lateral orbital incisions are indicated for those fractures that cannot be adequately reduced and fixated via the sublabial approach. Lower eyelid incisions are well hidden but can result in postoperative lower eyelid malposition and corneal exposure (entropion or ectropion). They should generally be reserved for moderately-to-severely displaced fractures requiring exposure of 3 buttresses for adequate repair (obviously, an isolated, comminuted, inferior orbital rim fracture will likely require a lid incision for repair).

Finally, for severely comminuted ZMC fractures with disruption of the zygomatic arch, a coronal scalp incision is required. Scalp incisions are associated with little morbidity, but often result in apparent scars and scalp anesthesia. As a general rule, the surgeon should continue to expose the fracture until adequate reduction is obtained and functionally stable fixation can be achieved.

A study by Farber et al indicated that no consensus exists in the treatment of ZMC fractures. For example, among physicians in various surgical specialties surveyed (plastic and reconstructive surgeons, oral and maxillofacial surgeons, otolaryngologists), the percentage of plastic surgeons who recommended an operation in the case of a minimally displaced fracture was significantly higher than among the other specialties. In a case of displaced fracture without diplopia and another of displaced fracture with diplopia, the investigators found that plastic surgeons were more likely to fix three or more buttresses.[34]

Zygomaticomaxillary buttress

The zygomaticomaxillary buttress is commonly fractured in tetrapod injuries. Use a transverse buccal sulcus incision to expose this area. The incision is well hidden, results in no external scar, and exposes the entire face of the maxilla. Incise the mucosa 1.5-2 cm above the gingiva using guarded electrocautery. This technique facilitates wound closure. Carry the incision from the midline to the second maxillary molar and extend as necessary. Take care to avoid entering the buccal fat pad posteriorly because this will result in fat prolapse, which obscures the surgical field. After the fracture is carefully reduced, apply an L-shaped 2-mm miniplate to fixate the ZMC to the palate. The image below shows the fixation of the ZMC. Apply at least 2 screws on each side of the fracture. Finally, irrigate the wound with antibiotic solution and close it with running, locking, 3-0 chromic suture.[#targetF1]

Frontozygomatic buttress

With more severe injuries, the frontozygomatic buttress is usually the second buttress to be exposed. Comminution at this site is uncommon, and fractures can often be reduced and plated through a limited incision.[35] Although a visible scar results, incisions at this site are well hidden and associated with little morbidity. The 3 most common approaches to the frontozygomatic buttress are the lateral upper lid blepharoplasty, lateral brow, and hemicoronal incisions.

Lateral upper lid blepharoplasty

A lateral upper lid blepharoplasty incision provides excellent access to the frontozygomatic suture line with better aesthetic results than the lateral brow incision. Mark a 2- to 3-cm skin incision in a natural crease on the lateral third of the upper eyelid. Then, retract the eyelid skin laterally over the frontozygomatic suture line. Incise the skin and orbicularis oculi muscle with a scalpel. Place retractors in the incision to lateralize the upper lid soft tissue over the frontozygomatic buttress. This protects the lacrimal gland or orbital fat. The levator aponeurosis is quite thin laterally and at low risk for injury. Use a guarded needlepoint electrocautery to incise the edematous subcutaneous tissue and periosteum exposing the fracture.

After the fracture is reduced, apply a 5-hole, 1.5- to 1.7-mm, low profile miniplate. Irrigate the wound with antibiotic solution, and close the subcutaneous tissues and orbicularis oculi muscle with 3-0 resorbable suture. Close the skin with interrupted 6-0 monofilament nonabsorbable suture, which is removed 5-7 days after the operation. Tissue glue can also be used for skin closure; however, extra caution must be used to avoid contact with the globe.

Lateral brow incision

The lateral brow incision is time tested and has been used by many surgeons. However, it has few if any advantages over the upper eyelid approach described above and results in a higher risk of visible postoperative scaring, alopecia of the lateral eyebrow, or both. Place the incision within or just below the lateral brow and carry it onto the frontozygomatic buttress (described above under blepharoplasty incision). Meticulous closure of the incision with eversion of the soft tissues will optimize the postoperative result.

Hemicoronal incision

The hemicoronal incision provides wide surgical exposure to the zygoma and frontal bone. Indications for this approach include superior orbital rim fractures and comminuted fractures of the ZMC, including the zygomatic arch. When possible, this approach should be avoided in patients with male pattern baldness.

Prior to incision, part or shave the hair between the vertex and the superior helical root. Place the incision at least 5 cm behind the hairline. A zigzag or "w" pattern can be used to help camouflage the incision. This is most effective in patients with straight hair that falls over the suture line. If necessary, the incision can be extended across the midline for additional exposure.

After injection with local anesthetic, incise the skin with a scalpel, starting at the vertex and moving toward the helical root. Carry the incision through the galea aponeurosis, leaving the pericranium and temporalis muscle fascia (deep temporal fascia) intact. Apply Raney clips to control blood loss. Special care must be taken to avoid injury to the temporal branch of the facial nerve that lies in the temporoparietal fascia (superficial temporal fascia).

The galea aponeurosis elevates easily from the pericranium. Use careful blunt dissection to elevate the temporoparietal fascia free from the temporalis muscle fascia. Join the 2 dissection planes sharply at the temporal line. The incision can be carried across the midline to the contralateral ear for more exposure or for access to the frontal sinus and orbital rims. To expose any fracture of the frontozygomatic buttress or orbital rim, the periosteum can be incised and elevated. Alternatively, the pericranium can be incised at the vertex with the skin incision and carry out the entire central dissection in a subperiosteal plane. If there is any risk of frontal sinus or nasoorbitoethmoid injury, maintain the pericranial flap intact for possible closure of CSF leaks.

Reduce the fractures and apply 1.5- to 1.7-mm miniplates. Using resorbable monofilament sutures, resuspend the soft tissues to the flap and the temporalis muscle fascia. This reduces the risk of postoperative ptosis of the facial soft tissues. Close the galea aponeurosis with a 3-0 resorbable polyglycolic suture and the scalp with staples. Leave a 0.25- inch Penrose drain in place for 24 hours, and apply a pressure dressing for 3-5 days.

Infraorbital buttress

The orbital rim, transconjunctival, and subciliary incisions are 3 common surgical approaches to the orbital rim. An endoscopic approach may also be useful.

Orbital rim incision

Position a 3- to 4-cm incision directly over the bony orbital rim approximately 1.5-2.0 cm below the lower lid margin. Carry the incision directly through the skin, orbicularis oculi muscle, subcutaneous tissue, and periosteum. While this approach is faster than eyelid incisions and is associated with minimal risk of postoperative eyelid malposition, it results in a visible cutaneous scar and can be associated with lower eyelid edema. Consequently, most surgeons avoid this incision except in patients with significant rhytides and minimal concerns of an external scar.

Transconjunctival approach

This approach requires a thorough understanding of lower eyelid anatomy. The technique offers a well-concealed incision, has a low risk of lower lid ectropion, and provides excellent exposure to the orbital rim and floor.[24, 36, 37, 38, 39, 40] The dissection can be performed in a preseptal or postseptal (retroseptal) plane.

For a preseptal approach, place a corneal shield over the globe. Inject a small amount (0.5-1.0 mL) of local anesthetic into the conjunctival incision line. The incision runs along the inferior border of the tarsal plate between the punctum and the lateral commissure. Place two 6-0 silk retraction sutures through the gray line of the lower eyelid and retract them inferiorly to expose the palpebral conjunctiva.

Use a guarded needlepoint or bipolar cautery to gently cauterize the incision site. Incise the mucosa and the capsulopalpebral fascia just below the tarsal plate with a number 15 blade. Place a 6-0 retraction suture through the free inferior margin of the palpebral conjunctiva. Retract the free margin superiorly over the globe to expose the dissection plane.

Carry the dissection inferiorly between the orbital septum (deep) and the orbicularis oculi muscle (superficial) along an avascular plane. Once a small pocket has been formed, use a Sewall retractor to gently elevate the globe and a Desmarres retractor to depress the lower eyelid. Take care to keep the orbital septum intact, and avoid exposure of orbital fat or injury of the inferior oblique muscle.

Once the orbital rim periosteum is exposed, use a guarded-needlepoint cautery to expose the bony rim and fracture. A periosteal elevator can then be used to raise the orbital floor periosteum and evaluate the extent of any orbital blowout fracture. Handle the periosteal edges carefully and keep them intact to assist with the closure.

Repair large orbital blowout fractures with an onlay graft covering the orbital defect and resting securely on a stable rim of bone at the periphery of the defect. Take great care to view the posterior aspect of the defect and insert the implant onto the posterior shelf of orbital floor bone (see Endoscopy). Implant materials may range from calvarial bone, septal/auricular cartilage, or porous polyethylene. Nonporous materials such as silicone sheeting are more prone to migration, infection, and extrusion.

When greater medial or posterior orbital exposure is anticipated, a lateral canthotomy and cantholysis can be performed. Before the lower lid conjunctival incision, place a scalpel or scissor on the lateral commissure. Initiate the canthotomy at the junction of the upper and lower lids and carry it approximately 5 mm laterally. Place the incision in a crows-foot wrinkle, if present. Placing anterior traction on the raw surface of the lower lid exposes the inferior crus of the lateral canthal tendon. Then use scissors to sever this tendon close to the bony insertion. When adequate mobility is achieved, the lower lid freely moves away from the globe. Then complete the dissection as previously described.

Once the orbital rim fractures are completely exposed, the injuries are reduced and plated with 1.0- to 1.3-mm microplates. Caution must be used to avoid catching periorbital fat on the drill shaft. A 5-hole miniplate is used with isolated fractures. For comminuted injuries, longer plates are required. In these instances, the reduction is approximated with a central defect, and the plate is applied. The small intervening segments then are lagged up to the plate, reapproximating their premorbid location. The surgeon must be aware that this adds a certain level of error into the reduction. Confirm accurate reduction of the other buttresses before application of the spanning plate.

Repair of the orbital floor should be delayed until the anterior orbital rim fractures have been reduced. Reduction of the rim fractures provides landmarks for the anterior margin of the orbital floor and a stable ledge for fixation of any implant. After all fractures are repaired, close the periosteum over the orbital rim with 5-0 resorbable sutures. Reapproximate the palpebral conjunctiva with running 6-0 fast-absorbing gut sutures. A 5-0 polydioxanone suture on a half round needle is then passed through the lateral free edge of the tarsal plate. The suture is then passed (from deep to superficial) through the periosteum overlying the lateral orbital tubercle of Whitnall.

Make an attempt to place this suture high and slightly on the internal surface of the superior orbital rim. A 6-0 fast-absorbing gut suture then is placed to reapproximate the gray line of the superior and inferior lids. The suture is left long and tethered laterally under the first skin sutures. Interrupted 6-0 nylon sutures are used to reapproximate the skin.

The primary advantages of this approach include a hidden scar and protection of the periorbita inferior oblique muscle. A theoretical disadvantage of the preseptal approach includes a slightly increased risk of lower lid malposition (when compared with the retroseptal approach) because the orbicularis oculi muscle is elevated from the orbital septum.

The postseptal (retroseptal) approach directly exposes the orbital rim through the orbital fat pad. It involves placement of a Sewall elevator in the fornix to elevate the globe superiorly and a Desmarres retractor to depress the lower lid. The conjunctiva is incised, and the orbital rim is exposed directly through the orbital fat. This technique is very rapid because it does not require meticulous dissection of the orbital septum. This reduces the risk of postoperative lower lid ectropion. However, the lack of dissection planes during the retroseptal approach increases the risk of inferior oblique muscle injury. Reduction and plating can also be more difficult secondary to the prolapse of orbital fat into the surgical field. Fracture reduction and repair are completed as described above. The conjunctival incision is closed with 6-0 fast absorbing gut sutures.

Subciliary approach

Inject local anesthetic into the lower eyelid skin 2 mm below the lash line (from the lower lid punctum to the lateral canthus). Use a scalpel to incise the skin, keeping the orbicularis oculi muscle intact. Reflect the eyelid skin from the orbicularis oculi muscle 4-6 mm inferiorly. Use fine scissors to bluntly dissect the orbicularis oculi muscle free from the orbital septum at the lateral aspect of the incision. Carry a tunnel medially just deep to the orbicularis oculi muscle moving toward the medial canthus. Take care to avoid exposure of orbital fat as the scissors are used to join the tunnel with the external skin incision.

The result is a stair-step incision that closes in layers, and reduces the risk of postoperative lower lid ectropion. The dissection is then completed as previously described (see transconjunctival dissection), and the orbital rim is exposed. This technique keeps the lower lid retractors intact and eliminates the need for a lateral canthotomy and cantholysis.

Disadvantages include an external incision and an increased risk of postoperative lower eyelid ectropion when compared to the transconjunctival approach.

Endoscopic approach

The utility of the sublabial incision can be greatly enhanced with the use of a 4-mm, 30-degree surgical endoscope. The sublabial application of a surgical endoscope can play a role in both the diagnosis and treatment of ZMC as well as orbital blowout fractures. Endoscopic visualization and reduction of zygomatic arch fractures has been described,[41] but is not the authors’ first choice.

For orbital rim fractures, sublabial insertion of the endoscope medial and lateral to the infraorbital nerve allows the surgeon to assess the reduction of the inferior orbital rim. Special care must be taken to avoid excessive tension on the infraorbital nerve while attempting to obtain an adequate cavity for endoscopic exposure. The endoscope can then be used to assist with application of a 1.0-mm miniplate along the orbital rim. Because the screws will be oriented toward the orbit from below, the surgeon must take special care to avoid extension of the screws through the rim and into the orbit. After extensive soft tissue dissection and completion of the repair, soft tissue resuspension should be performed. A midface suspension stitch (4-0 or 5-0 monofilament absorbable suture) can be passed from the malar fat pad, superolateral to the temporalis muscle fascia or a titanium plate. Traction on the suture allows the surgeon to resuspend the malar fat pad at the desired height.

In orbital blowout fractures, transmaxillary reduction of orbital blowout fractures is currently on the cutting edge of endoscopic facial fracture repair. The idea of transmaxillary repair of orbital blowout fractures is not new. Walter described it in 1972.[42] Most surgeons did not embrace the technique for fear of injury to the orbital contents while performing a blind reduction. The endoscope now provides an excellent view of prolapsed orbital contents into the maxillary sinus and greatly improves the accuracy of a transmaxillary reduction. However, great caution must be used when applying this technique. The surgeon must have extensive experience in traditional orbital approaches and repair of orbital blowout fractures.

After endoscopic identification of small trap door fractures (see Diagnostic procedures), torn mucosa from around the fracture site should be removed with a Cottle or Freer elevator. The prolapsed orbital contents can then be reduced into the orbital cone. Finally, the bone fragments can be snapped back into place without the need for an orbital implant.

Small-to-intermediate fractures can be repaired in a similar fashion. Often, removal of small bone fragments is necessary. After reduction of the orbital contents, the orbital floor can be reconstituted by inserting an appropriately trimmed piece of porous polyethylene (0.85 mm thick) through the maxillary antrostomy, maxillary sinus, and into the orbital defect.

Large defects must be repaired via traditional open approaches. However, endoscopic assistance can be an extremely helpful addition. After traditional exposure of the orbital floor defect, it can be very challenging to view the stable bone of the posterior orbit when looking tangentially along the orbital floor. However, precise placement of the implant into the posterior orbit and on top of the bony shelf (without impinging on the optic nerve) is vital to accurate orbital reconstruction. The author believes that sublabial, transmaxillary endoscopic visualization of the orbital floor makes identification of the posterior orbital shelf and implant placement much easier and more reliable, while reducing the risk of optic nerve injury.

The endoscopic approach to the orbital rim and floor is an evolving technique that shows great promise in augmenting our current methods. As the techniques and instrumentation are refined, the need for external incisions will be significantly reduced. However, the surgeon must show caution with any endoscopic repair and be inclined toward a traditional approach if any question of adequate reduction or entrapment of orbital contents exists.

Zygomatic arch buttress

Four common approaches to the zygomatic arch are available.

Direct percutaneous approach

This technique is less commonly used but offers a rapid and minimally invasive method for repair of mildly displaced ZMC fractures. After general endotracheal anesthesia, insert a towel clip, heavy suture, or bone hook through the skin at the site of injury. Pass the instrument deep to the zygomatic arch and apply lateral traction to reduce the fracture. Caution must be used to avoid any slippage of the instrumentation because tissue laceration and injury to the facial nerve may result. If the fracture reduces easily and is stable to palpation, no further treatment is necessary. Stability and accuracy of reduction can be difficult to assess if soft tissue edema is present.

Although an incision is avoided, this technique does not allow direct observation, bimanual surgical manipulation, or stabilization of the fracture.

Temporal (Gillies) approach

The author prefers this approach for isolated fractures that are mild to moderately displaced.

This approach requires a 2-cm incision placed behind the temporal hairline approximately 6 cm above the zygoma. Carry the incision through the skin, temporoparietal fascia (superficial temporal fascia), and temporalis muscle fascia (deep temporal fascia). Use a Freer elevator to dissect a tunnel superficial to the temporalis muscle and deep to the zygomatic arch.[43]

Limit dissection around the fracture site to minimize the risk of fracture destabilization. Once the dissection is beneath the zygomatic arch, insert a Boise elevator and apply lateral pressure to reduce the bone fragments. A Rowe-Killey elevator also can be used for resistant or partially healed fractures.

Care must be taken to avoid using the parietal scalp as a fulcrum for these instruments. This can result in a parietal skull fracture. The need for rigid fixation is uncommon in isolated arch fractures. An empty Glasscock ear dressing or a molded aluminum finger cot (foam padded) can be taped over the zygomatic arch for 3-7 days after the repair.

Advantages of this technique include no visible scar, protection of the facial nerve, and bimanual reduction of the fracture.

Transoral approach

The transoral approach uses a gingivobuccal sulcus incision (see Zygomaticomaxillary buttress). Expose the anterior insertion of the zygomatic arch, and place a Boies elevator deep to the zygomatic arch. Apply lateral pressure to reduce the fracture. Avoid using the dental arch as a fulcrum as palatal fractures can occur.

Advantages of this technique include no visible scar, protection of the facial nerve, and bimanual reduction of the fracture.

Hemicoronal

The hemicoronal approach is generally reserved for severe injuries with marked comminution of the zygomaticomaxillary complex. Expose the temporalis muscle as described earlier (see Frontozygomatic buttress).

Approximately 2 cm above the zygomatic arch, make a horizontal incision through the superficial layer of the temporalis muscle fascia, and expose the temporal fat pad. Use a periosteal elevator to dissect onto the zygomatic arch.

Caution must be used to stay in a subperiosteal plane. If the dissection is too superficial and disrupts the temporoparietal fascia, the facial nerve can be injured. If the dissection is too deep, the temporal fat pad can be disrupted and result in postoperative temporal wasting. Exposing the lateral aspect of the zygomatic arch from the root of the zygoma to the frontozygomatic buttress completes the dissection.

Adjunctive procedure for primary repair of trigeminal nerve

Recently, treating trigeminal nerve injuries (such as the infraorbital nerve in ZMC fractures) with microsurgical repair has been shown to be effective. Small, monofilament microsutures are used to complete the neurorrhaphy.[44]

Appropriate antibiotic coverage should be initiated before surgery and continued for approximately 24 hours postoperatively. Many surgeons continue antibiotic therapy for 7-10 days; however, the literature does not support any clear benefit from this practice.

Fracture reduction

Fracture reduction is indicated in all patients who are likely to have a residual aesthetic deformity or functional deficit. A review of the literature reveals that 77-94% of patients with zygomaticomaxillary complex (ZMC) fractures require surgical reduction.[21, 23, 13] Many authors advocate closed reduction of ZMC fractures through more limited surgical approaches.[21, 24, 45] Accurate closed reduction can be achieved in many cases.

However, many reports in the literature cite difficulty in obtaining adequate reduction, even with direct observation.[4, 24, 25, 36] Therefore, closed reductions are generally reserved for fractures with mild displacement and little soft tissue edema. Also, the patient must be willing to accept an increased risk of postoperative asymmetry.

The key to successful open surgical repair is strict adherence to basic principles. These principles include adequate (but not excessive) exposure, precise reduction, and accurate stabilization when necessary. The surgeon must view the fractures and remove any granulation tissue that may inhibit bone apposition and healing. Use geometric irregularities on opposing fracture surfaces for precise anatomic alignment. Slight inaccuracies in reduction at one fracture site can be amplified at distant sites.

Key buttresses that can be observed include the frontozygomatic, inferior orbital rim, zygomaticomaxillary, and the lateral orbital wall (zygomaticosphenoidal). The frontozygomatic, zygomaticomaxillary, and inferior orbital rim exposures provide information about displacement of the ZMC primarily in the x (horizontal) and y (vertical) planes.

Unfortunately, ZMC fractures rarely cause displacement in only one plane. Rotation of the ZMC often occurs along the axis of the frontozygomatic buttress because of masseter muscle pull.[45, 46] Visualization of the lateral orbital wall (zygomaticosphenoidal buttress) in combination with the frontozygomatic and zygomaticomaxillary buttresses provides information in all 3 planes, including rotation of the ZMC and changes in orbital volume. An accurate 3-dimensional understanding of the ZMC is essential to precise reduction and avoidance of postoperative asymmetry.

Rigid fixation

ORIF is the mainstay of ZMC fracture repair.[4, 7, 8, 9] However, controversy exists regarding the need for 1-, 2-, or 3-point fixation.[10, 11, 12] Some authors have advocated closed reduction in most cases.[13, 14, 15, 16] Other authors contend that all ZMC fractures require some form of fixation.[17, 18]

Davidson (1990) evaluated this complex issue.[47] Six skulls (12 zygomas), devoid of soft tissue, were placed in a test frame with a fiberoptic orthogonal measuring device. Traumatic ZMC fractures were simulated with a sagittal saw. The fractures were then reduced and fixated using different combinations of plates and wires.

The study revealed that 3-point fixation using miniplates conferred the greatest stability. However, 3-point wire fixation was only slightly less stable. Mixing wires with miniplates reduced the stability in proportion to the number of wires used. Minimal increases in stability were added using 3-point miniplate fixation when compared to 2-point miniplate fixation, regardless of the application site.

The authors concluded that stable fixation can be achieved with a miniplate on the frontozygomatic suture line and a single wire on a second buttress. Acceptable stability can be achieved with single-point miniplate fixation at the frontozygomatic suture line or the infraorbital rim.[47] These results do not take into account variables such as fracture comminution rotatory forces of the masseter muscle or the type of skin incision necessary to apply the fixation.

A retrospective study by Shokri et al suggested that when handled by an experienced surgeon, single-point fixation can effectively be used in noncomminuted ZMC fractures during ORIF. The study included 162 patients in whom single-point fixation of the zygomaticomaxillary buttress was used for noncomminuted ZMC fractures. The investigators found that none of the individuals in the study needed orthognathic surgery or cheek implants for malar asymmetry or required revision ORIF of the fracture. Moreover, neither hypoglobus nor enophthalmos developed in any of the cases. During the mean 3.4-month follow-up, complications included tooth loss (1 patient; owing to the presence of a root in the fracture line), intraoral plate pressure (7 patients; with plate exchange performed in 2 patients), and wound infection (8 patients).[48]

A retrospective study by Luck et al indicated that in pediatric patients with displaced ZMC fractures, two-point fixation is an effective repair procedure. Patients with deciduous dentation who underwent this surgery (all of whom were under age 15 years) demonstrated a lower overall complication rate (0%) than did those who were treated with with one- or three-point fixation (both 75%).[49]

In a clinical setting, the need for ORIF is based on the anatomy, severity, and stability of the fracture. A mildly displaced tetrapod fracture with good stability may be amenable to closed reduction and require no fixation. Most fractures that require open reduction can be fixated with 1 or 2 miniplates.

Comminuted ZMC fractures with bone loss can often require 3-point fixation and may even need 4-buttress stabilization with bone grafting. Miniplates are helpful in stabilizing free-floating segments and fixating bone grafts harvested from the anterior wall of the maxillary sinus, calvaria, or iliac crest.

Most surgeons use titanium plates for internal fixation; however, wire fixation is time tested, inexpensive, and requires no special instrumentation. Unfortunately, wire fixation often requires more surgical exposure to see and grasp the wire on the deep surface of the fracture. Wires are also extremely difficult to use with comminuted fractures.

Although miniplate fixation is more expensive and requires special instrumentation, it has several advantages. The surgeon does not need to see the deep surface of the fracture. Once the fracture is reduced adequately, a plate can be applied from the lateral surface. Plates are also much more effective with bone grafts and comminuted fractures. Most importantly, plate fixation adds stabilization to the fracture site in 3 spatial planes. Wires primarily prevent distraction of the fracture (x plane). They do not inhibit hinging or rotation at the fracture site (y and z planes). Miniplates add stabilization in all 3 spatial planes (x, y, and z), inhibiting distraction, rotation, and hinging at the fracture site.

Resorbable plates offer many of the same advantages as titanium plates; however, they are reabsorbed within 3-12 months. The primary indication for the use of resorbable plates is in the pediatric population where long-term facial growth is a concern. Unlike titanium plates, resorbable plates contour very easily in situ. After heating the plate with warm water, small inaccuracies in bending can be corrected without difficulty. Mesh panels can also be applied. They offer multiple sites for insertion of screws and can be beneficial for comminuted fractures.

Many patients see the use of an absorbable material as a significant benefit; however, little evidence exists to support greater clinical efficacy. Disadvantages of the resorbable plates include larger size and the need for tapping. A 2-mm resorbable plate has a higher profile than a 2-mm titanium plate and the equivalent strength of a 1.6-mm titanium plate. The larger resorbable screws also require more bone stock for application. In areas such as the orbital rim and nasoorbitoethmoid complex, resorbable plates can be prohibitively large. All resorbable screws require tapping before the screw can be inserted. This adds surgical steps and time to the procedure.

A study by Song et al indicated that fibrin glue can effectively be used to restore the anterior wall of the maxillary sinus in ZMC fracture. In the study, of 234 patients with ZMC fracture, severe fractures of the maxillary sinus’s anterior wall were repaired with bone grafts cemented with fibrin glue. Computed tomography (CT) scanning revealed that the grafted fragments remained in place postoperatively.[50] However, although this study demonstrated a novel potential use for fibrin glue, the clinical relevance and necessity of its employment in this way is unproven, since the anterior maxillary sinus wall is commonly left unrepaired in ZMC fracture, with no adverse functional or aesthetic effects resulting.

Patients are observed for approximately 24 hours, and perioperative antibiotics are administered for 1-7 days depending the degree of wound contamination. Parenteral steroid administration may be used to reduce postoperative facial edema. Pressure dressings are applied only after coronal incisions to avoid postoperative hematoma. Gross visual acuity is checked in the recovery area and daily for the next 48 hours or until discharge.

Cutaneous sutures are removed 5-7 days after the operation. Scalp staples are removed 10-14 days after the operation. Patients are then observed in follow-up visits after 1 month and again after 3 months.

Ophthalmologic

The most serious complication associated with a zygomaticomaxillary complex (ZMC) injury is blindness. While this condition may occur at the time of injury, multiple cases of iatrogenic blindness have been reported in the literature[51] ; therefore, a preoperative ophthalmologic examination is essential. The surgeon should also assess pupillary size and symmetry prior to fracture repair. Intraoperative changes in pupillary size must be addressed. Local anesthesia containing epinephrine can result in transient pupillary dilation, which will resolve. Dilation of the pupil while traction is being applied to the globe (provided the other eye is closed) is a sign of optic nerve injury.

Periodic intraoperative evaluation of pupil size and symmetry is recommended. Postoperative visual acuity checks are essential. Mild postoperative visual acuity changes can occur transiently in up to 30% of patients.[52] Significant postoperative loss of visual acuity is an indication for orbital reexploration, particularly if orbital implants were placed.

Persistent diplopia is probably the most common ophthalmologic complication of ZMC fractures, occurring in approximately 7% of patients.[7, 53] Diplopia is noted most frequently in upward and far lateral gaze. Underlying etiologies include extraocular muscle entrapment, neurapraxia, or muscle contusion. If an iatrogenic entrapment is suspected, an urgent CT scan should be obtained. If the diagnosis is confirmed, rapid reoperation and release of the entrapped extraocular muscle is imperative. Diplopia that is felt to be secondary to neurapraxia or extraocular muscle contusion should be monitored for at least 6 months before any ophthalmologic surgical intervention is contemplated.[26]

Lower eyelid malposition

The lower eyelid can be separated into an outer lamella (skin and orbicularis oculi muscle) and an inner lamella (tarsal plate and conjunctiva). Lower eyelid ectropion occurs from excessive scarring in the outer lamella. This condition is most commonly associated with the subciliary approach. The resultant effect can range from simple scleral show to corneal exposure and ulceration.

Appling (1993) cited a 28% incidence of permanent scleral show with the subciliary approach and a 3% incidence with the transconjunctival approach.[54] Frank ectropion is observed in 0-44% of patients undergoing the subciliary approach and in 0-1.2% of patients undergoing the transconjunctival approach.[36, 54, 55]

Lower eyelid entropion results from injury to the inner lamella and occurs most commonly with the transconjunctival approach. Eyelid entropion can result in corneal exposure and abrasion of the cornea by the eyelashes. In many cases, lid malposition and scleral show can be treated effectively with simple massage. If the lid malposition is severe and does not respond to conservative management, surgical repair can be performed. Ectropion is often associated with excessive lower lid laxity prior to surgery. A lateral tarsal strip procedure can reposition and tighten the lower lid. If the ectropion is severe, this procedure can be combined with lysis of the anterior lamella contracture and skin grafting. Entropion can be effectively treated with a release of the contracture and placement of a palatal mucosal spreader graft in the posterior lamella. The spreader graft facilitates eversion of the lower lid and prevents repeat contracture.[56]

Facial asymmetry

Postoperative facial asymmetry occurs in 20-40% of patients.[57] Although facial fracture reductions can be strenuous and time consuming, failure to obtain adequate exposure and precise reduction at the time of initial repair often results in cosmetic deformities. Most postoperative irregularities require no surgical intervention; however, major asymmetry occurs in 3-4% of patients. Osteotomies and bone grafting may be required.[36, 57]

A study by Kim et al indicated that cone-beam CT scanning can be used to evaluate soft tissue asymmetry following open reduction of unilateral ZMC fracture. The study involved patients who had undergone the open reduction procedure at least 3 months prior to symmetry assessment, with a control group of patients without ZMC fracture being used for comparison. Cone-beam CT scanning revealed that, compared with controls, the ZMC patients had statistically significant asymmetry at various landmarks, including the zygion, point of cheek, and frontozygomatic point.[58]

Paresthesias

ZMC fractures often traverse the infraorbital foramen and result in infraorbital nerve injury. Preoperative evaluation and documentation of infraorbital nerve function is strongly recommended. Patients should be counseled that the sublabial incision itself will result in some transient postoperative anesthesia of the upper gingiva. The incidence of persistent sensory dysfunction ranges from 22-65% for open reductions and 9-40% for closed reductions.[24, 36] In one large series, iatrogenic injuries were noted in 11% of open reductions.[36] Excessive traction or surgical manipulation of the infraorbital nerve during exposure and fracture reduction will also increase the risk of postoperative paresthesias. While these symptoms can be distressing to the patient, observation and reassurance are the most appropriate treatments. Attempts at surgical decompression or ablation are highly unpredictable.[4]

Coronal incisions will also result in postoperative paresthesias/anesthesia of the supraorbital and supratrochlear dermatomes distal to the incision. Aggressive manipulation of the nerve at the foramina can exacerbate these symptoms. Resolution of the paresthesias is slow and can be extremely frustrating to some patients. All patients should be warned regarding the postoperative sequelae and counseled that resolution of the symptoms (which may be partial or complete) cannot be expected for 3-12 months after the surgery.

Miscellaneous

Plate exposure: In the absence of infection, intraoral exposure of plates or wires can be monitored conservatively. These wounds often granulate with appropriate oral hygiene. Persistent exposure for longer than 3 months, evidence of loose hardware, or gross infection are indications for hardware removal.

Cold sensitivity: Patients will rarely complain of pain over titanium implants with cold exposure. When present, cold sensitively is an indication for hardware removal.

Sinusitis: Zingg (1991) reported a 7% incidence of maxillary sinus opacification after ZMC fracture repair[36] : however, only 1.6% of patients were symptomatic. Postoperative sinusitis was related directly to the severity of injury. Reserve sinus surgery for patients who do not respond to conservative medical management.

Unacceptably poor surgical outcomes are uncommon. Significant facial asymmetry requiring surgical revision occurs in 3-4% of patients. Postoperative infection rates are extremely low, and these infections nearly always resolve with oral antibiotics. In general, the long-term prognosis after repair of zygomaticomaxillary complex (ZMC) fractures is very good.

Future advances in the treatment of facial trauma most likely will involve more extensive use of endoscopy for minimally invasive repair of traumatic injuries. The authors are using computer imaging software that can compare the more nonfractured side and create a computer model for reconstruction planning.[59] Image-guidance surgery systems may also play a role in optimizing fracture reduction.