Fractures that occur within the orbital bones are referred to as blowout fractures. These fractures may affect any of the orbital perimeters, namely the floor (i.e. inferior border), the medial wall (i.e. lamina papyracea), the lateral wall and the roof (i.e. superior border).
The orbit houses the eyeball and serves primarily to protect our eyes and hold them in their positions. Any force to the face with enough energy and the resultant transmission of forces to the orbital bones can result in fracture. Forces generated by motor vehicular accidents, balls, elbows or fists may suffice.
Types of Blowout Fractures
Blowout fractures may be classified based on the perimeter of the orbit that they affect. The most common of the blowout fractures are those of the inferior orbital wall or floor.
These fractures, in approximately half of the cases, occur in unison with fractures affecting the medial orbital wall. The majority of orbital floor fractures occur in the posterior-medial portion of the bone in relation to the infraorbital groove.
With orbital floor fractures, prolapse of orbital fat into the maxillary sinus may be seen. This may be sometimes accompanied by inferior rectus muscle prolapse.
Following inferior blowout fractures, the second commonest types of orbital fractures are those of the medial wall or lamina papyracea. With these types of fractures there is also prolapse of the medial rectus muscle and orbital fat into the air cells of the ethmoid. Fractures to the superior border of the orbit are rare, and those to the lateral walls are even rarer. This is because the latter border is fortified with thicker bone and more muscle; thus, lateral fractures are seen in very severe accidents with extensive injury to the craniofacial area. Superior blowout fractures may involve the neighboring sinus as well as the anterior cranial fossa, thereby presenting with leakage of cerebrospinal fluid.
Succeeding trauma to the orbit, the patient may present with tenderness, bruising and swelling. These are the most common signs and symptoms associated with blowout fractures. In addition to them, patients may complain of diplopia or double vision. There may be numbness anywhere in the surrounding areas as well as bleeding from the nose, which is referred to as epistaxis in medical terminology. In very severe cases there may be loss of the eye itself and/or its functions together with depression of central nervous system functioning if there are extensive injuries to the skull and/ or brain.
The imaging modality of choice with blowout fractures is CT scan and this helps to ascertain the extent as well as the location of the fracture. Moreover, it allows for the identification of complications as a direct result of the fracture. These include rupture of the eyeball, hemorrhage, entrapment of the extraocular muscles and prolapse of orbital fat and/or muscle. Surgical repair as soon as possible is necessary once all other emergent and life-threatening complications from the trauma are taken care of and the patient is stable enough to undergo the operation.
Reviewed by Afsaneh Khetrapal Bsc (Hons)