eMedicine Specialties > Ophthalmology > Orbit

Orbital Fracture, Zygomatic

Author: Stuart Seiff, MD, FACS, Emeritus Professor of Ophthalmology, University of California San Francisco; Chief, Department of Ophthalmology, San Francisco General Hospital; Consultant, Oculofacial and Aesthetic Plastic Surgery, California Pacific Medical Center and Mills Peninsula Medical Center
Coauthor(s): Jesus Torres, MD, Fellow, Section of Oculoplastic Surgery, Hospital de Viladecans, Spain; Dan D DeAngelis, MD, FRCS(C), Ophthalmic Plastic and Reconstructive Surgery, Assistant Professor, Department of Ophthalmology and Vision Sciences, University of Toronto; Susan Carter, MD, Clinical Associate Professor of Ophthalmology, Institute of Ophthalmology and Visual Science, New Jersey Medical School
Contributor Information and Disclosures

Updated: May 13, 2009

Introduction

Background

The zygomatic bone occupies a prominent and important position in the facial skeleton. The zygoma forms a significant portion of the floor and lateral wall of the orbit and forms a portion of the zygomatic arch, otherwise known as the malar eminence, which plays a key role in the determination of facial morphology. Fractures of the zygomatic complex occur because of the rotation of the zygoma associated with the disarticulation of the zygomatic bone at the zygomaticofrontal suture (along the lateral orbital rim), the zygomaticomaxillary suture (medially), and along the zygomatic arch to the temporal bone (see Media file 1).^1,2

Anatomically, the zygomatic bone contains foramina that allow for the passage of zygomaticofacial and zygomaticotemporal arteries and corresponding nerves of the second division of the trigeminal nerve that supply sensation to cheek and anterior temple. Similarly, the infraorbital nerve also courses the floor of the orbit and exits the infraorbital foramen or notch. Consequently, fractures of the zygomatic arch can lead to hypoesthesia in the corresponding dermatome. Muscle attachments along the zygomatic arch include the origin of the masseter, the zygomaticus major, and some fibers of the temporalis fascia. The Whitnall tubercle, which serves a critical role in the maintenance of eyelid contour as the attachment site for the lateral canthal tendon, is located on the zygomatic bone 2 mm behind the lateral orbital rim.³

Pathophysiology

The zygoma is the main buttress between the maxilla and the skull, but, in spite of its sturdiness, its prominent location makes it prone to fracture. The mechanism of injury usually involves a blow to the side of the face from a fist, from an object, or secondary to motor vehicle accidents. Moderate force may result in minimally or nondisplaced fractures at the suture lines. More severe blows frequently result in inferior, medial, and posterior displacement of the zygoma. Comminuted fractures of the body with separation at the suture lines are most often the result of high-velocity motor vehicle accidents.

In general, displaced fractures involve the inferior orbital rim and orbital floor, the zygomaticofrontal suture, the zygomaticomaxillary buttress, and the zygomatic arch. However, occasionally, a direct blow to the arch results in an isolated depressed fracture of the arch only.³

Frequency

United States

Zygomatic fractures are the second most common fracture of the facial bones following nasal bone fractures.⁴

Mortality/Morbidity

As many as 5% of patients with zygomatic fractures have associated ophthalmic injuries.

Sex

Males are afflicted with zygomatic fractures more commonly than females by a 4:1 ratio.

Age

Most cases of zygomatic fractures occur in young patients in their second to third decades of life.

Clinical

History

• Vision can be threatened as a result of direct ocular injury or intraorbital hemorrhage.
• Binocular diplopia is noted in as many as 30% of zygomatic fractures. This can be secondary to muscle entrapment, neuromuscular injury, or intramuscular hematoma.
• Difficulty with mastication, otherwise known as trismus, can occur because of masseter spasm or bony impingement of the coronoid process.
• In some patients, ipsilateral epistaxis also is noted as a result of lacerated maxillary sinus mucosa.

Physical

• Since most of these patients are involved in multisystem trauma, involvement by a trauma team for airway, breathing, and circulatory status is essential.
• Ophthalmic evaluation, including globe integrity, should be performed promptly. Inferior displacement of the lateral canthal tendon is common. Proptosis may be present due to orbital edema or hemorrhage. Acute orbital hematoma may cause vision compromise and should be managed appropriately.⁵
• Periorbital and/or subconjunctival ecchymosis are seen in as many as 50% of patients.
• Significant malar depression can be seen with step defects at the infraorbital rim, frontozygomatic suture, and zygomatic buttress of the maxilla intraorally.
• Fractures of the zygomatic bone evoke pain on palpation in 70% of patients.
• Paresthesias in the distribution of the infraorbital, zygomaticofacial, or zygomaticotemporal nerves can occur.
• Posterior displacement of the fracture fragment may impinge on movement of the mandible causing difficulty with mastication. Inferior displacement of the lateral canthal angle may indicate inferior migration of the fractured zygomatic bone. Although these are not true orbital blowout fractures, entrapment of orbital contents, enophthalmos, and diplopia with restriction of motility may occur because of the contributions of the zygomatic bone to the orbital floor. Use of the Hertel exophthalmometer in the assessment of relative enophthalmos or exophthalmos may be complicated because the lateral orbital rim, which is displaced in most zygomatic complex fractures, serves as a reference point for this instrument. Consideration should be given to the use of the Naugle exophthalmometer in these cases, which uses the frontal bone as a reference.
• Crepitus from subcutaneous emphysema or proptosis and visual loss from orbital emphysema may occur with forceful nose blowing. Patients should be cautioned against this.

Causes

The mechanism of injury usually involves a blow to the side of the face from a fist, from an object, or secondary to motor vehicle accidents. Studies show that 80% of these injuries are due to motor vehicle accidents.

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