William Lang 1899 first isolated orbital blowout fracture
Converse and Smith 1957 coined the term “blow-out”
Pfeiffer 120 cases 1945 where 24 instances enophthalmos and 24 cases “internal orbital fracture” without rim fracture
Seven bones frontal bone, maxilla, zygoma, ethmoid, lacrimal bone, greater and lesser wings of the sphenoid, and the palatine bone
orbital process of frontal
lesser wing of sphenoid
Greater wing of sphenoid
Orbital surface of Maxilla
Orbital process of palatine
Anterior lacrimal crest on frontal process of maxilla Maxill
body of sphenoid leading to optic canal
4-5cm depth, volume = 30mls
Ligamentous supports of the globe
comprises the medial and lateral check ligaments, the medial and lateral canthal ligaments, an inferior sling, and a superior sling.
Inferior sling includes not only Lockwood’s ligament and extensions, but also the fascial condensations around the inferior rectus muscle and Tenon’s capsule
Superior sling is composed of Whitnall’s ligament, condensations of the levator and superior rectus fascia, and Tenon’s capsule.
Musculofibrous Ligaments of Koornneef
Koornneef makes particular note of the intricate network of connective tissue septae within the orbital fat space. This connective tissue has also been shown to contain an abundance of collagen fibers, smooth muscle cells, and fibroblasts.
The fat, both within the muscle cone and extraconal, is diffusely interconnected by fine ligaments to the periosteum lining the bony orbital walls, to each of the extraocular muscles, and to the bulbar fascia.
These are more prominent in the inferior medial orbit. The connective tissue septae have an intimate relationship with the so-called check ligaments and suspensory ligament of Lockwood.
These structures are both supportive and, in part, serve to limit eye movement.
Whereas arterioles branch radially within discrete adipose pockets, veins (which course along fibrous septa) have diffuse anastomoses and are abundantly interconnected with extraorbital veins by branches perforating the orbital walls. Venous drainage of the orbit follows a central to peripheral flow pattern.
Isolated roof fractures rare in adults because of the protection afforded by the supraorbital rim, frontal bone, and frontal sinus.
Frequencies of pure blow out fractures (Burn PRS 1999)
interruption of circulation to critical muscle areas.
Assess with Hess Charts, binocular vision and field, forced duction, radiography and sometimes coronal computed tomography.
forced duction test is unreliable during the first week after injury because nonmechanical causes of restriction often give spurious results.
Important to test in 1 weeks time if conservative Mx is chosen
73% will have resolution of diplopia with conservative management
Entrapment in children
White-eyed blowout fracture
Children may be more prone to pure trap door fractures (60% of floor fractures) than adults and incarceration of the muscle in such fractures can lead to permanent damage of the neuromuscular complex.
Presents with marked motility restriction and nausea/vomiting
Several studies have demonstrated more complete resolution of diplopia if these cases are operated on very early or as soon as the diagnosis is made - best results within 2 days (Jo Gruss), opthamol journals say 1 week.
In children, the flexible orbital floor fractures and is displaced inferiorly, allowing infraorbital tissue to enter the fracture site.
The trapdoor then recoils, trapping the inferior rectus.
Consequently, the ophthalmic division of the trigeminal nerve is stimulated and, through the reticular formation, transmits the signal to the vagus nerve, which then carries the efferent impulse to the stomach, producing nausea.
Nausea and vomiting have a 83% PPV.
With entrapment, a compartment syndrome of the inferior rectus may result.
Small orbital floor fractures were more likely to have high compartment pressures around the inferior rectus and that diplopia was more likely to persist.
The resultant ischemia and inflammation may lead to permanent fibrosis and impaired extraocular motility.
soft-tissue dissection and reduction was much more difficult in the patients whose surgery had been delayed.
In most patients, the trapdoor needed to be depressed to release the valve effect on the soft tissues
simple reduction of the soft tissue was noted to predispose to recurrent herniation of the soft tissue into the fracture. To prevent a postoperative herniation and entrapment, the fractured orbital floor was patched - pericranial shave graft best
Aetiology enlargement of the bony cavity
amount of periorbital fat
status of the check ligaments arising from the sheath of the lateral and medial rectus muscles
tone of the rectus muscles, which exert slightly more pull posteriorly than the oblique muscles do anteriorly.
soft-tissue scarring and contracture pulling the globe backward
even when the orbital floor is completely absent, Lockwood’s ligament will support the eye as long as its anchoring points— to Whitnall’s tubercle of the zygoma laterally and to the lacrimal crest medially
Pearl described a coronal plane from the lateral orbital rim to the anterior lacrimal crest (divides the globe into 2 equal halves)
Fat loss anterior to the axis of the globe does not affect the anteroposterior location of the eye itself.
Only fractures located posterior to the axis produce enophthalmos,
Only operative procedures that create bony enlargement and fatty displacement behind this axis correct exophthalmos.
Only adding volume behind the axis of the globe can correct enophthamos.
If there is sufficient space between the top of the globe and the bony roof, volume additions at the axis of the globe can correct vertical dystopia without producing exophthalmos.
the severity of the enophthalmos is a measure of the difference between the anterior corneal surface and the lateral orbital rim
Manson noted that enophthalmos occurs when orbital floor disruption exceeds a total area of 2 cm2, the bone volume change exceeds 1.5 cc (5% of orbital volume), and significant fat and soft-tissue displacements occur.
Enophthalmos of 2.5 to 3 mm correlated with a mean increase in orbital volume of 3.4 mL (10%), while enophthalmos of 3.5 to 5 mm correlated with increase in orbital volume of 7.1 mL.(20%)
Parsons and Mathog reported that surgical exploration to prevent enophthalmos is indicated for all orbital blowout fractures with 3 mm of displacement of either the inferior or medial wall.
Severe >4 cm
Hertel exophthalmometer > 2mm 10-14 days after trauma is cosmetically significant and is an indication for surgery.
Orbital edema that is present initially may mask any enophthalmos. Therefore, measurements must be rechecked once the orbital edema has subsided. This usually occurs 10 days to 2 weeks after injury.
Displacement of the medial and lateral canthal ligaments
inferior displacement and antimongoloid slant of the fissure with lateral canthal tendon displacement
If the lateral end cannot be found, the tendon should be sutured to the periorbita or through holes drilled through the lateral orbital rim at the orbital tubercle. It is important to remember that the lateral canthal tendon attaches to the orbital tubercle located 5mm posterior to the lateral orbital rim at level of the upper limbus. If not repaired correctly, the lateral canthal angle will be displaced too far anteriorly.
telecanthus with medial canthal detachment
If no soft tissue remains or the medial orbital wall is fractured, the tendon can be wired to the adjacent intact medial wall, transnasally to the contralateral medial orbital wall, or to the contralateral medial canthal tendon.
deepening of the supratarsal fold occur due to posterior displacement of the globe.
distinguished from true ptosis by the fact that there is no change in the distance between the inferior lid margin and the pupil;
intraorbital air mass can cause central retinal artery occlusion – treat with CTguided needle aspiration of the air mass if accompanied by visual deterioration, rising intraocular pressure, severe pain, or motility disturbances.