Residency · Residency · Oral Maxillofacial Surgery

Zygomaticomaxillary Complex Fractures

Overview

The zygomaticomaxillary complex (ZMC) fracture, also called the tripod or tetrapod fracture, involves separation of the zygoma at its four articulations. The zygoma forms the lateral orbital wall, orbital floor, zygomatic arch, and malar eminence. ZMC fractures are the second most common midface fracture after nasal fractures. They result from direct lateral force to the cheek (assault, falls, MVC, sports). Correction is critical for facial aesthetics (malar projection), orbital volume, and masticatory function.

Anatomy

The zygoma articulates with four bones. The zygomaticofrontal (ZF) suture is the junction with the frontal bone at the lateral orbital rim. The zygomaticomaxillary (ZM) buttress is the articulation with the maxilla at the anterolateral maxillary wall. The zygomaticotemporal (ZT) suture is the zygomatic arch junction with the temporal bone. The zygomaticosphenoid (ZS) suture is the junction at the lateral orbital wall with the greater wing of the sphenoid. The zygoma contributes to the lateral orbital wall and orbital floor, the anterior wall of the maxillary sinus, the zygomatic arch (with the temporal bone), and the malar eminence (facial projection and contour). Structures at risk include the infraorbital nerve (V2), which runs through the orbital floor, orbital contents (globe, extraocular muscles, orbital fat), the masseter origin on the zygomatic arch, and the temporalis fascia passing over the arch.

Classification

Zingg Classification

Type A represents incomplete ZMC fractures: isolated arch fracture (A1), lateral orbital wall fracture (A2), or infraorbital rim fracture (A3). Type B is a complete tetrapod fracture with all four articulations disrupted as a single fragment. Type C is a comminuted ZMC fracture with multifragment involvement.

Knight and North Classification (Historical)

This historical system divides fractures into six groups: Group I (no significant displacement), Group II (arch fracture), Group III (unrotated body depression), Group IV (medially rotated body), Group V (laterally rotated body), and Group VI (comminuted).

Manson Classification (by Energy)

Low-energy fractures are minimally displaced and may not require surgery. Medium-energy fractures are displaced but have intact fragments amenable to ORIF. High-energy fractures are comminuted and require ORIF with possible bone grafting.

<image>Anterior and lateral skull views showing the four articulations of the zygoma (zygomaticofrontal, zygomaticomaxillary, zygomaticotemporal, and zygomaticosphenoid sutures) highlighted with the typical ZMC fracture lines, alongside the Zingg classification system (Type A incomplete, Type B complete single fragment, Type C comminuted)</image>

Clinical Presentation

Malar flattening (depression of the cheekbone) is best assessed from the bird's-eye view above the patient. Periorbital ecchymosis and edema can mask underlying bony depression. Subconjunctival hemorrhage often has lateral extension with no posterior limit visible. Infraorbital nerve paresthesia causes numbness of the cheek, upper lip, lateral nose, and maxillary teeth and is present in 50-90% of ZMC fractures. Trismus results from impingement of the depressed arch on the coronoid process or temporalis muscle. Diplopia occurs with orbital floor involvement and soft tissue herniation or muscle entrapment. Enophthalmos from increased orbital volume due to floor and wall disruption may be masked acutely by edema. A step deformity is palpable along the infraorbital rim or lateral orbital rim. Epistaxis is ipsilateral, from disruption of the maxillary sinus mucosa. Limited mouth opening results from arch depression or pain.

Diagnosis

Clinical examination compares cheek projection bilaterally using the bird's-eye view, palpates rims, tests sensation, and checks ocular movements. CT face with axial, coronal, and 3D reconstruction is the gold standard. All four articulations are assessed, orbital floor integrity is evaluated, orbital volume is measured (comparing sides), the degree of displacement and comminution is assessed, and the zygomatic arch is evaluated. The submentovertex plain film view shows arch displacement but has been largely replaced by CT.

Management

Non-Operative

Non-operative management is indicated for nondisplaced fractures and stable fractures without functional or significant aesthetic deformity. A soft diet is maintained for 6 weeks, nose blowing is avoided (sinus precautions), and serial clinical follow-up ensures no delayed displacement or enophthalmos. Infraorbital nerve paresthesia is monitored and usually resolves in 3-6 months.

Closed Reduction

The Gillies temporal approach uses an incision behind the hairline in the temporal fossa, with an elevator placed deep to the temporalis fascia beneath the zygomatic arch to elevate the depressed zygoma. The Keen intraoral approach uses an elevator placed through the maxillary buccal sulcus to elevate the zygoma from below. The Carroll-Girard screw is a percutaneous screw placed into the malar eminence and used as a handle for manipulation and reduction. Closed reduction is indicated for minimally displaced fractures at all four sutures that are stable after reduction. If the fracture is unstable after closed reduction, ORIF is required.

Open Reduction and Internal Fixation (ORIF)

Indications

ORIF is indicated for displaced fractures (significant malar flattening, step deformity), fractures unstable after closed reduction, trismus from arch impingement, orbital floor involvement with diplopia, entrapment, or significant volume increase, and comminuted fractures.

Surgical Approaches

The lateral brow incision accesses the ZF suture and is the most reliable indicator of reduction at this site. A subtarsal or transconjunctival incision accesses the infraorbital rim and orbital floor -- transconjunctival with lateral canthotomy provides extended orbital access, while subtarsal offers more direct exposure but risks lower eyelid malposition. An upper buccal sulcus incision accesses the ZM buttress and anterior maxillary wall. A coronal incision accesses the arch and ZF suture for comminuted or complex fractures. Existing lacerations are utilized when available.

Fixation Strategy

The number of fixation points depends on fracture stability and displacement. One-point fixation with a miniplate at the ZF suture is sufficient if the fracture is stable after reduction at this site. Two-point fixation at the ZF suture plus the infraorbital rim or ZM buttress is standard for moderate displacement. Three-point fixation at the ZF suture, infraorbital rim, and ZM buttress is used for unstable or comminuted fractures. Additional arch plating through a coronal approach is used for comminuted arch fractures. The ZF suture is the most reliable indicator of anatomic reduction and should be assessed first. The ZM buttress is the strongest fixation point with the thickest bone, supporting masticatory forces. Hardware consists of 1.5 or 2.0 mm miniplates with monocortical screws at each fixation point.

Orbital Floor Repair

Orbital floor repair is indicated when there is a significant floor defect, herniation of orbital contents, muscle entrapment, or orbital volume increase greater than 1.5-2 cm3. Materials include titanium mesh, porous polyethylene (Medpor), and resorbable plates. Access is through a transconjunctival or subtarsal incision. Critical landmarks include the inferior orbital fissure (the posterior limit of dissection) and the infraorbital nerve.

<image>Intraoperative photographs showing ORIF of a ZMC fracture: lateral brow incision exposing the displaced zygomaticofrontal suture with miniplate fixation, transconjunctival approach to the infraorbital rim with miniplate fixation and titanium mesh reconstruction of the orbital floor, and upper buccal sulcus approach showing miniplate fixation at the zygomaticomaxillary buttress</image>

Post-Operative Management

Ice packs and head elevation are used. Sinus precautions are maintained for 6 weeks. A soft diet is followed for 4-6 weeks. Infraorbital nerve recovery is monitored. Serial ophthalmic assessment is performed if the orbital floor was involved. Follow-up imaging is obtained at 6 weeks.

Complications

Persistent malar flattening from inadequate reduction is the most common aesthetic complaint. Enophthalmos results from inadequate orbital volume restoration or secondary orbital fat atrophy. Infraorbital nerve paresthesia is common, with most cases improving by 6-12 months. Persistent diplopia from entrapment or scarring may require revision orbital floor repair. Ectropion or scleral show may result from a subtarsal or subciliary approach to the infraorbital rim. Persistent trismus occurs from ongoing arch depression or fibrosis. Infection is uncommon with appropriate technique (less than 3%). Hardware palpability is an issue in thin patients, especially at the lateral orbital rim. Subtle asymmetry in malar projection may persist despite adequate reduction.

Clinical Pearls

The bird's-eye view (looking from above the patient's head) is the best clinical way to assess malar projection by comparing both sides. ZF suture alignment is the most reliable intraoperative indicator of accurate reduction and should be evaluated first. If the fracture returns to a displaced position after closed reduction, it is unstable and requires ORIF -- an unstable reduction should not be left in place. The orbital floor should always be checked on CT because even seemingly simple ZMC fractures can have significant orbital floor involvement. Infraorbital nerve paresthesia is expected and usually recovers, and patients should be counseled that this may take months. Delayed treatment beyond 2-3 weeks makes reduction progressively more difficult due to early healing, so unnecessary delays should be avoided. When there is doubt about orbital volume, the floor should be explored because post-traumatic enophthalmos is very difficult to correct secondarily. A transconjunctival approach should be used when possible for the infraorbital rim, as it carries lower risk of ectropion than the subtarsal approach.

References

• Ellis E, Kittidumkerng W. Analysis of treatment for isolated zygomaticomaxillary complex fractures. J Oral Maxillofac Surg. 1996.
• Zingg M, et al. Classification and treatment of zygomatic fractures: a review. J Oral Maxillofac Surg. 1992.
• Manson PN, et al. Subunit principles in midface fractures: the importance of sagittal buttresses, soft tissue reductions, and sequencing treatment of segmental fractures. Plast Reconstr Surg. 1999.
• Czerwinski M, et al. Quantitative analysis of the orbital floor defect after zygoma fracture repair. J Oral Maxillofac Surg. 2008.
• Kim JH, et al. Comparison of surgical outcomes between one-point and two-point fixation in zygomaticomaxillary complex fractures. J Craniofac Surg. 2016.
• Barry CP, et al. The zygomaticomaxillary complex fracture: clinical update. Br J Oral Maxillofac Surg. 2021.

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