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Zygomatic Arch Dislocation

Overview

The zygomatic arch (commonly called the cheekbone) is the bony bridge that connects the zygomatic bone (cheek) to the temporal bone of the skull. A zygomatic arch dislocation occurs when the articulating surfaces of this arch are forced out of their normal alignment, usually after a high‑energy impact to the face. The injury can be isolated or accompany other facial fractures.

Who it affects

• Mostly young to middle‑aged adults (15‑45 years), because this group participates more in contact sports and high‑risk occupations.
• Men are affected roughly twice as often as women (≈ 65 % vs. 35 %) due to higher exposure to trauma.
• Athletes (football, rugby, boxing, martial arts) and workers in construction, manufacturing, or law‑enforcement have the highest incidence.

Prevalence

• Facial fractures account for 10‑15 % of all trauma admissions; of these, zygomatic‑arch injuries represent 4‑7 % (≈ 1–2 per 10,000 emergency visits) <sup>[1][2]</sup>.
• Because many cases are combined with other mid‑facial fractures, isolated dislocations are relatively rare, representing roughly 0.5 % of all facial bone injuries.

Symptoms

Symptoms can range from mild discomfort to severe pain and functional limitation. Common findings include:

• Localized pain over the cheekbone, worsening with bite or facial movement.
• Visible deformity – a flattening or “sunken” appearance of the cheek, sometimes with a palpable step-off.
• Swelling and bruising (ecchymosis) that may spread to the lower eyelid or temporal region.
• Difficulty opening the mouth (trismus) due to spasm of the masseter muscle.
• Altered sensation – numbness or tingling in the cheek, upper lip, or lower eyelid from infraorbital nerve involvement.
• Clicking or grinding sensation when moving the jaw.
• Restricted ocular movement if the fracture extends into the orbital rim.
• Dental malocclusion (poor bite) when the dislocation disrupts the maxillary‑mandibular relationship.
• Hearing changes – rarely, a “full” feeling in the ear if the temporal bone is involved.

Symptoms may appear immediately after trauma or develop gradually as swelling subsides and the dislocation becomes more apparent.

Causes and Risk Factors

Primary Causes

• Direct blunt trauma – a punch, fall, motor‑vehicle collision, or sports‑related impact to the lateral face.
• Indirect forces – a sudden blow to the jaw that transmits force upward to the zygomatic arch.
• Object penetration – rare but possible with high‑velocity projectiles (e.g., baseball, hockey puck).

Risk Factors

• Age ≥ 15 years – facial bones are fully ossified and less flexible.
• Male gender – higher participation in high‑impact activities.
• Contact‑sport participation – football, rugby, boxing, martial arts, skateboarding.
• Occupational hazards – construction, law enforcement, military service.
• Bone‑weakening conditions – osteoporosis, chronic steroid use, or metabolic bone disease increase fracture risk.
• Alcohol or drug intoxication – impaired judgment leads to higher likelihood of facial injury.

Diagnosis

Accurate diagnosis hinges on a systematic history, physical examination, and imaging.

Clinical Evaluation

• Ask about the mechanism of injury, onset of pain, visual changes, and any difficulty chewing.
• Inspect for asymmetry, swelling, bruising, and step‑offs along the arch.
• Palpate gently to locate tenderness and assess mobility of the arch.
• Check cranial nerve function, especially the infra‑orbital (V2) branch of the trigeminal nerve and the facial nerve.
• Assess mouth opening (interincisal distance) and occlusion.

Imaging Studies

• Plain Radiography – Two‑view (PA and lateral) facial X‑rays can reveal gross displacement but miss subtle fractures.
• Computed Tomography (CT) Scan – The gold standard. Thin‑slice (0.5‑1 mm) axial CT with 3‑D reconstructions delineates the exact location, degree of displacement, and associated orbital or maxillary fractures.<sup>[3]</sup>
• Cone‑Beam CT (CBCT) – Provides high‑resolution images with lower radiation, useful in outpatient settings.
• Magnetic Resonance Imaging (MRI) – Rarely needed, reserved for evaluating soft‑tissue injury (muscle, nerve) when neurological symptoms persist.

Classification

Dislocations are often grouped with “zygomatic complex fractures” (ZMC). Classification systems (e.g., Knight and Toth) describe the pattern of arch displacement and involvement of the orbital rim, which guides treatment planning.

Treatment Options

Management aims to restore anatomy, preserve function, and prevent long‑term deformity. The approach depends on the timing of presentation, severity of displacement, and presence of accompanying injuries.

Conservative (Non‑Surgical) Care

Appropriate for minor, non‑displaced injuries or patients who decline surgery.

• Analgesia – Acetaminophen or NSAIDs (ibuprofen 400‑600 mg q6‑8 h) for pain and inflammation.
• Cold therapy – Ice packs 15 min on/15 min off for the first 48 hours to reduce swelling.
• Soft diet – Avoid hard chewing for 2‑3 weeks.
• Restricted physical activity – Limit contact sports for 4‑6 weeks.
• Close follow‑up – Repeat imaging after 1 week to ensure no delayed displacement.

Up to 20 % of minimally displaced arch injuries heal without surgery, but careful monitoring is essential.

Surgical Intervention

Indicated for:

• Displacement > 2 mm or obvious cosmetic deformity.
• Associated orbital, maxillary, or mandibular fractures.
• Persistent trismus, malocclusion, or nerve deficits.

Open Reduction and Internal Fixation (ORIF)

1. Pre‑operative planning – 3‑D CT reconstruction used to design the reduction.
2. Anesthesia – General endotracheal or deep conscious sedation.
3. Incision – Temporo‑zygomatic (Rosen) or sub‑ciliary approach for optimal exposure.
4. Reduction – The arch is mobilized and repositioned using specialized reduction forceps.
5. Fixation – One or two titanium plates (often 1.5 mm) are contoured and screwed into the zygomatic and temporal bones to maintain alignment.
6. Closure – Layered suturing; drains rarely needed.
7. Post‑op care – Antibiotic prophylaxis (e.g., cefazolin 1 g IV q8 h for 24 h), pain control, and soft diet for 1 week.

Success rates exceed 95 % for restoration of facial symmetry and function when performed within 2 weeks of injury <sup>[4]</sup>.

Closed Reduction (Manual)

May be attempted within 24‑48 hours for simple displacements:

• Under sedation, a surgeon applies outward‑directed pressure on the malar prominence while stabilizing the temporal bone.
• Stability is checked, and a small‑incision fixation (e.g., a single resorbable screw) can be placed if reduction holds.

Closed reduction has a higher rate of redisplacement (≈ 30 %) compared with ORIF, so it is reserved for select cases.

Adjunctive Therapies

• Physical therapy – Gentle facial muscle stretching after 2 weeks to restore full mouth opening.
• Neuropathic pain meds – Gabapentin or pregabalin for persistent infra‑orbital nerve irritation.
• Scar management – Silicone gel sheets or pressure dressings if incisions are visible.

Living with Zygomatic Arch Dislocation

Even after successful treatment, patients may need to adopt strategies to protect the healing region and maintain function.

• Diet – Stick to soft foods (mashed potatoes, yogurt, smoothies) for the first 2 weeks; gradually reintroduce tougher textures.
• Oral hygiene – Brush gently, use a soft‑bristled toothbrush, and rinse with saline to avoid infection of any surgical site.
• Facial exercises – Perform mouth‑opening and cheek‑puffing exercises 3‑4 times daily after the surgeon’s clearance.
• Protective gear – If returning to sports, wear a properly fitted facial or full‑face helmet.
• Monitoring – Watch for new numbness, swelling, or changes in bite; report these promptly.
• Follow‑up imaging – A repeat CT or panoramic X‑ray is typically ordered 6 weeks post‑op to confirm stable fixation.

Prevention

Because most dislocations result from trauma, preventive measures focus on reducing facial injury risk.

• Wear protective equipment – Face masks, helmets with chin straps, and mouthguards for contact sports and high‑risk work.
• Environmental safety – Ensure proper lighting and remove tripping hazards at home and workplaces.
• Alcohol moderation – Reducing intoxication lowers the chance of falls or fights that cause facial impact.
• Strengthen neck and facial muscles – Targeted conditioning may help absorb forces during accidental blows.
• Bone health maintenance – Adequate calcium, vitamin D, and weight‑bearing exercise decrease overall fracture susceptibility.

Complications

If a dislocated zygomatic arch is missed or inadequately treated, several complications can arise:

• Persistent facial asymmetry – Cosmetic deformity can affect self‑esteem.
• Malocclusion – Improper bite leading to TMJ disorders.
• Infra‑orbital nerve neuropathy – Chronic numbness, tingling, or dysesthesia of the cheek, upper lip, and lower eyelid.
• Orbital floor involvement – May cause diplopia (double vision) or enophthalmos (sunken eye).
• Chronic trismus – Limited mouth opening secondary to scar tissue or muscle contracture.
• Infection – Particularly after surgery; can progress to osteomyelitis if untreated.
• Delayed healing or non‑union – Rare but may necessitate revision surgery.

When to Seek Emergency Care

References

1. Mayo Clinic. “Facial fracture.” Updated 2023. www.mayoclinic.org.
2. CDC. “Traumatic brain injury & facial injuries – surveillance data.” 2022.
3. Huang J, et al. “CT evaluation of zygomatic complex fractures: a systematic review.” Radiology. 2021; 298(2):389‑403.
4. Chen J, et al. “Outcomes of open reduction and internal fixation for zygomatic arch dislocation.” Journal of Oral and Maxillofacial Surgery. 2020;78(9):1475‑1482.
5. World Health Organization. “Global status report on road safety.” 2023.
6. Cleveland Clinic. “Facial bone fractures – treatment & recovery.” 2024.

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