Orbital Floor Fractures (Blowout Fractures)

Orbital floor fractures may result when a blunt object, which is of equal or greater diameter than the orbital aperture, strikes the eye. The globe usually does not rupture, and the resultant force is transmitted throughout the orbit causing a fracture of the orbital floor. Signs and symptoms can be quite varied, ranging from asymptomatic with minimal bruising and swelling to diplopia, enophthalmos, hypo-ophthalmia (ie, hypoglobus), and hypoesthesia of the cheek and upper gum on the affected side. Treatment is titrated to the degree of injury. ^[1] See the image below.

Coronal CT scan of orbits demonstrating loss of orbital floor on the left in contrast to the normal orbital floor on the right.

The orbit and its contents are affected by orbital floor fractures. Direct fractures of the orbital floor can extend from orbital rim fractures, while indirect fractures of the orbital floor may not involve the orbital rim. The cause of the fracture is thought to be from increased intraorbital pressure, which causes the orbital bones to break at their weakest point. This is usually the medial orbital floor. Another theory is that compression of the inferior orbital rim causes direct buckling of the orbital floor. In either case, if the intraorbital pressure is great enough at the time of injury, orbital contents can be forced into the fracture site and possibly into the maxillary sinus. ^[2]

Mortality/Morbidity

With simple blowout fractures, there may be no morbidity at all, or the patient may complain of diplopia, enophthalmos, or hypoesthesia of the cheek and gum. Edema and ecchymosis of the eyelids and periorbital region usually are seen but are temporary. With any injury that involves a sinus, air may escape into the orbit or subcutaneous tissues. This is called orbital emphysema.

Vertical diplopia may be caused by entrapment of the perimuscular tissue surrounding the inferior rectus muscle in the fracture site. This results in limited upgaze and may cause pain on attempted upgaze as well. Damage to the third nerve branch to the inferior rectus muscle also may cause limited vertical motility. Severe pain with limited horizontal and vertical movements can be indicative of more severe orbital hemorrhage or edema. ^[3]

Enophthalmos may result when large orbital floor fractures occur and orbital contents prolapse into the maxillary sinus. If a medial wall fracture also has occurred, the enophthalmos may be compounded due to prolapse of orbital contents into the ethmoid sinus. Orbital edema that occurs at the time of injury initially may mask the enophthalmos, but the sunken eye appearance will become more apparent over the following 1-2 weeks as the edema subsides.

Fractures along the floor usually affect the infraorbital groove and therefore the infraorbital nerve. The resultant neuropraxia causes hypoesthesia of the cheek and upper gum on the affected side. This is usually temporary but can last up to 6 months or longer. In severe injuries, the hypoesthesia may be permanent.

Sex

Because the usual mechanism of injury is assault with a blunt object, the vast majority of cases occur in males. In a study of facial fractures in an urban population, 81% of the patients were males.

Age

Because of the nature of the injury and its etiology (eg, assault), most orbital floor fractures occur in teenagers or young adults. ^[4]

Most cases do well, and most patients obtain resolution of diplopia and correction of enophthalmos.

Warn patients to avoid strenuous activity and to use common sense when determining their postoperative activity level.

Warn patients to avoid nose blowing for several weeks after the injury and repair.

Educate patients about nerve damage recovery. An injured motor nerve (third nerve branch) or sensory nerve (infraorbital nerve) can take weeks or months to return to normal. In some cases, the damage may be permanent.

For excellent patient education resources, visit eMedicineHealth's Eye and Vision Center and Skin Conditions and Beauty Center. Also, see eMedicineHealth's patient education articles Black Eye and Bruises.