Blow Out Fracture

Question 1

What are common causes of orbital trauma?

Answer 1

• Fist – perfect shape to fit into socket – often don’t fracture skull
• Elbow common in rugby
• Hockey ball

Question 2

What is the mechanism of fracture in BO#?

Answer 2

• Force of blow -> backward displacement of eyeball  IOP Pressure increases -> fracture in weakest point of orbital wall
• Not the force that fractures the eye  it is everything that is contained in orbit being compressed
• Floor is thinnest part so 1st bit to break – trap door floor break (eye drops & then bone (door) closes – can cut off blood supply to muscles – BAD!)
• Look for other things e.g. hyphaema – not just looking at fracture & diplopia

Question 3

What would the HESS plot look like in BO#?

Answer 3

• If at front of floor then biggest problem is elevation
• If at back then biggest problem is looking down
• Squashed mechanical field – RE lower than LE – massive overactions of contralateral synergist
• Px can’t elevate & can’t depress
• Px often has black eye – often have complete ptosis so cannot open eye & v sore
• CT scan – gold standard for if the maxilla-facial surgeons need to repair – only do this if muscles are trapped
• Otherwise tend to wait 7-14 days for swelling to go down – often just oedema (& then resolves)

Question 4

What are the signs of BO#?

Answer 4

• Enophthalmos – due to increased orbital volume – eye sitting back compared to other eye
  o May stay with them forever even if they’ve had floor replaced – face may be flattened on that side due to surgery (as they will have had to remove fat)
• Diplopia – due to EOM entrapment – so much swelling that eye cannot move
  o Eyes may be fine in PP or slightly depressed
  o Cannot look up or look down – these pxs should not be driving
• Orbital emphysema – especially when fracture is into an adjacent paranasal sinus (Black Eyebrow Sign)
  o White eye BO# - eye is white but eyebrow is black
  o Check optic nerve is not compressed by this pressure – check pupils, colour vision
• Malar region numbness – due to injury to infraorbital nerve
  o Press underneath px’s eye – looking for numbness (if numb then know this is damaged)
   Px will often not be keen for you to do this as they are in so much pain
• Hypoglobus - inferior displacement of the globe in the orbit

Question 5

Describe the classification of BO#?

Answer 5

• BO# can occur through one or more of orbital walls:
  o Inferior (floor) – biggest issue is looking up
  o Medial Wall (lamina papyracea) – restriction of adduction or abduction
  o Superior (roof)
  o Lateral Wall
• Will know it is a BO# - send them immediately to hospital
• Mechanical problem that often restriction is in opposite to where it is

Question 6

What is the most common BO#? Which nerve runs below the orbit?

Answer 6

• Most common is a floor fracture
• Can have medial wall fracture or superior too
• Directly underneath the orbit is maxillary sinuses
  o Nerve running here is infraorbital nerve – pxs can lose function of this
• Really do not want pxs to blow their nose – blows air up into fracture in eye

Question 7

Describe inferior BO#?

Answer 7

• Inferior BO# are most common
• Orbital fat prolapses into maxillary sinus & may be joined by prolapse of IR muscle
• In children, the fracture may spring back into place (trapdoor fracture)
• Most fractures occur in floor posterior & medial to the infraorbital groove
• In ~50% of cases, inferior BO# fractures are associated with fractures of medial wall
• Teardrop sign, contents have herniated down into sinus – needs repaired, not close on own -> often they close on their own quickly

Question 8

Describe medial BO#?

Answer 8

• Medial BO# are 2nd most common type, occurring through lamina papyracea
• Orbital fat & MR muscle may prolapse into ethmoid air cells
• Pic: fracture on medial wall on RE – medial wall
• Problem with abduction

Question 9

Describe superior BO#?

Answer 9

• Pure superior BO# (w/o associated orbital rim fracture) are uncommon
  o Frontal bone is v strong – would have to be enormous trauma - rare
  o Will not happen with a punch
• Usually seen in pxs with pneumatisation of orbital roof
• Fractures may only involve the sinus, the anterior cranial fossa (less common), or both sinus & anterior cranial fossa
• Fractures communicating w/ anterior cranial fossa are at risk for CSF leak & meningitis

Question 10

Describe lateral BO#?

Answer 10

• Pure lateral BO# are rare
• Bone is thick & bounded by muscle
  o Sometimes take away some of lateral bone to relieve pressure when have proptosis (thyroid eye disease)
• If fractures are present they are usually associated w/ orbital rim or other significant craniofacial injuries
• Trauma from side
• More likely to have floor or medial wall fracture

Question 11

What are the signs to look for in BO#?

Answer 11

• In addition to evaluating location & extent of fracture (s) – other features requiring assessment & reported include:
  o Presence of intraorbital (usually extraconal) haemorrhage: may result in stretching or compression of optic nerve
  o Globe injury/rupture
  o EOM entrapment: suspected if there is an acute change in angle of muscle
  o Prolapse of orbital fat & muscles is what gives enophthalmos
• Quick look on direct ophthalmoscope then straight to hospital

Question 12

What are the indications for surgery in BO#?

Answer 12

• Significant enophthalmos – cosmetically looks sunken in
• Significant diplopia
• Muscle entrapment, especially with “trapdoor fracture” in children
• Large area fractures
• Must be significant
• Binocular single vision from peering down – would rather it is in depression than in elevation (depends on px’s job)

Question 13

What is the timing of surgery in BO#?

Answer 13

• Many surgeons elect for semi-delayed or late repair
  o Allows for assessment for noticeable enophthalmos, diplopia, or EOM impairment once swelling has subsided
• Must be balanced against risk of developing fibrosis & more permanent structural impairment with longer delayed management
• Typically wait 7-14 days for oedema to settle – orthoptist would see them every few days to monitor

Question 14

What clinical examinations should be carried out in a BO#?

Answer 14

• Vision – are they seeing?
• Cover test – PP – often bigger up & down
• Motility – limited to start with
• Fusion – can they keep it single enough to cope, may get increased vertical fusion
• Colour vision – checking optic nerve
• Ocular exam, cornea, retina etc – checking for other signs of rupture
• Fields – looking for other retinal signs