Zygomaticomaxillary Complex Fracture

Zygomaticomaxillary complex fracture, also called tripod or trimalar fracture, is a fracture of the cheek bone with separation from the frontal bone, the maxilla, the sphenoid and the temporal bone. It is the second commonest facial fracture after nasal fracture, and results mainly from assault, falls and road traffic collisions.

The four articulations that fail are the zygomaticofrontal suture, the infraorbital rim and zygomaticomaxillary buttress, the zygomaticotemporal suture (arch) and the zygomaticosphenoid suture in the lateral orbital wall.

Pathophysiology. A direct lateral blow displaces the zygoma inward, downward or rotated, depending on the force and muscle pull of the masseter.

The orbital floor and lateral wall are disrupted, with risk of entrapment of orbital soft tissue, enophthalmos and diplopia. The coronoid process of the mandible can be blocked by the displaced arch, causing trismus.

Flattening of the cheek prominence, swelling and bruising, a palpable step at the infraorbital rim or zygomaticofrontal suture, infraorbital numbness, subconjunctival haemorrhage, unilateral epistaxis, trismus, malocclusion, periorbital emphysema, and diplopia on upgaze or downgaze with limited eye movement. Enophthalmos and a lowered pupil level may appear as swelling settles.

Reduced visual acuity, proptosis, a tense orbit, pupil changes, severe pain and absent eye movement suggest retrobulbar haemorrhage and need immediate action.

• CT of the facial bones with axial, coronal and 3D images, the investigation of choice.
• Ophthalmic assessment before treatment: visual acuity, pupillary reactions, colour vision, eye movements, diplopia, and forced duction testing when entrapment is suspected, with orbital examination by ophthalmology for any visual abnormality.
• Assessment of infraorbital nerve sensation and of trismus.
• Assessment of the cervical spine and head injury depending on the mechanism.
• Tetanus status.

Differential diagnosis.

• Isolated zygomatic arch fracture
• Orbital blowout fracture
• Le Fort II or III fracture
• Nasoorbitoethmoid fracture
• Retrobulbar haematoma
• Mandibular coronoid or condylar fracture with trismus
• Soft tissue contusion without fracture

• Orbital emergency: retrobulbar haemorrhage with visual loss needs immediate lateral canthotomy and cantholysis. Acetazolamide 500 mg intravenously and mannitol 0.5 to 1 g/kg intravenously are used while arranging definitive care, with ophthalmology. Reduce acetazolamide with renal impairment.
• Undisplaced fractures without functional problem: conservative care, with soft diet, avoiding pressure on the cheek, and analgesia.
• Displaced fractures: reduction and fixation after swelling falls, usually within 7 to 14 days (up to 3 weeks). Minimally displaced arch type fractures may need temporal approach reduction alone. More often, open reduction and internal fixation at 1 to 3 points (zygomaticofrontal suture, infraorbital rim or the zygomaticomaxillary buttress) through a transconjunctival or subciliary, upper buccal sulcus, and lateral brow incision. Stability is tested after reduction.
• Orbital floor repair with titanium mesh or a porous implant for defects over 2 cm2 or with entrapment, enophthalmos or herniation.
• Antibiotics: amoxicillin with clavulanic acid 1.2 g intravenously every 8 hours for the first 24 hours perioperatively, with no routine extension unless infection exists. Clindamycin 600 mg intravenously every 8 hours in penicillin allergy. Reduce the dose of amoxicillin with clavulanic acid when eGFR is under 30.
• Tetanus toxoid 0.5 mL intramuscularly if vaccination is incomplete or the last dose was over 10 years ago, with tetanus immunoglobulin 250 IU intramuscularly (500 IU after 24 hours or heavy contamination) when status is unknown or incomplete.
• Nasal precautions: no nose blowing for 2 weeks and sneezing with the mouth open, because of the risk of orbital emphysema. Decongestant for 3 to 5 days (xylometazoline 0.1% one spray each nostril up to three times daily).
• Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food when appropriate. Chlorhexidine 0.2% mouthwash.
• Complications: enophthalmos, diplopia, infraorbital numbness, malunion with facial asymmetry, trismus, ectropion, and blindness.

Monitoring. Review at 1 week, 2 weeks, 6 weeks and 3 months for eye movements, vision, sensation, trismus and facial symmetry, with CT at 6 weeks if function or contour is abnormal.

Referral and escalation. Refer to oral and maxillofacial surgery and ophthalmology. Emergency referral for visual loss, retrobulbar haemorrhage or entrapment with oculocardiac reflex (bradycardia, nausea, syncope), especially in children.