2. Blow out fracture
Caused by sudden increase in intraorbital
pressure,resulting from trauma to soft tissues of
orbit.
NOT ALL ORBITAL FLOOR FRACTURES ARE
BLOWOUT FRACTURES.
3.
4. Tennis ball or the human fist , the orbital contents are forced
backward into the narrower portion of the orbit . The increased
intraorbital pressure thus exerted causes a blow- out at the weakest
area of the orbital without fracturing the orbital rim. This type of
fracture may he referred to as "pure" blowout fracture .
The strong rim of the orbit protects against objects with a radius of
curvature greater than 5 em
An object having a curvature: of less than 5 cm may penetrate this
projective barrier and damage the globe. Such objects are balls,
hockey pucks, and {he tip of a footbalL Damage to the globe leading
to blindness may occur.
A champange bottle cork may damage the globe, because its radius
is less than 5 cm. However. its lesser propulsive force also makes it a
frequent cause of blowout fracture.
10. The fracture is often complicated by diplopia, which
is caused by a vertical muscle imbalance
secondary to entrapment of the orbital contents
Which may include the inferior rectus and inferior
oblique muscles and the surrounding facial
expansions into the dehiscence in the orbital floor.
11. Diplopia with enopthalamus- results from
incarceration of orbital contents into area of fracture
and tearing of periorbital.
With diplopia without enopthalamus- The condition
occurs with fixation of orbital contents in a linear
fracture.no escape of orbital fat
12. Without diplopia with enopthalamus- No fixation of
inferior orbital contents into area of fracture
…periorbital open so escape of orbital fat.
Without diplopia without enopthalamus- neither
fixation nor disturbance in anatomy of periorbital
cavity.
14. Clinical examination
Diplopia
Forced duction test- means of differentiating
entrapment of inferior rectus muscle from
weakness or paralysis of superior rectus.
PATHOGONOMIC OF BLOW OUT
21. Sensory nerve conduction loss
Anesthesia or hypoaesthesia in area of distribution
of infraorbital nerve.
Evidence of blowout fracture involving infraorbital
groove.
Absence of anesthesia-location of fracture is either
lateral,medial or posteror.
22. Treatment
3 goals
Disengage entrapped structures and restore oculatory
function;
Replace orbital fat into the orhital cavity if it has
prolapsed into the maxillary sinus;
Restore orbital cavity size and form to minimize
extraocular muscle imbalance and enophthalmos.
23. Timing of surgery
It is not necessary to operate immediately,
particularly if post- traumatic edema is present.
Delay beyond seven days is dangerous, particularly
in children, as bone regeneration is rapid and the
freeing of incarcerated orbital contents becomes
more difficult.
