In the вЂњbucklingвЂќ theory, blunt trauma to the face (such as a punch to the cheek) transmits a pressure wave posteriorly, acutely compressing the bones of the orbit in the anterior-posterior direction. The increased orbital pressure simultaneously fractures the bony floor and pushes the bone fragment downward, displacing the bone into the maxillary sinus, along with soft tissue from the orbit. As the intraorbital pressure increases dramatically and suddenly, the floor of the orbit вЂњblows outвЂќ inferiorly at the point of greatest weakness, just above the intraosseous course of the infraorbital neurovascular bundle. The eyeball is thrust posteriorly, transiently raising the pressure within the orbit. In the вЂњhydraulicвЂќ theory, the eyeball itself is struck directly from an object such as a fist or a baseball.

Two theories predominate to explain the occurrence of orbital вЂњblowoutвЂќ fractures. Orbital tissue herniating into the sinus through the resulting defect in the orbital floor may become entrapped, causing diplopia and possible oculocardiac reflex if the displacement of the bony fragment is large enough, enophthalmos may develop. The thin floor of the orbit, typically medial to the infraorbital neuromuscular bundle, is broken and a piece of this bone is generally displaced downward into the maxillary sinus. Patients who suffer blunt trauma to the globe or periocular area, especially directly on the globe or on the cheek, are at risk of developing an orbital floor fracture.

As one might suspect, it is this very thin area of the orbital floor overlying the neurovascular bundle where isolated orbital floor fractures frequently occur. By contrast, the bone of the lateral portion of the orbital floor averages 1.25 mm thick, over 5 times the thickness of the bone over the neurovascular bundle. The inferior orbital neurovascular bundle (comprising the infraorbital nerve and artery) courses within the bony floor of the orbit the roof of this infraorbital canal is only 0.23mm thick, and the bone of the posterior medial orbital floor averages 0.37 mm thick. The anatomy of the orbital floor predisposes it to fracture. A 'blowout Fracture of the orbital floor is defined as a fracture of the orbital floor in which the inferior orbital rim is intact.ДЇractures of the orbital floor are common: it is estimated that about 10% of all facial fractures are isolated orbital wall fractures (the majority of these being the orbital floor), and that 30-40% of all facial fractures involve the orbit. Orbital floor fracture, also known as вЂњblowoutвЂќ fracture of the orbit. 3.1.1 Selection of patients for surgery and timing of repair.

Skull orbit