Orbital fracture

Orbital fractures can be complex due to the variability of injuries and their proximity to the globe, brain and cranial nerves.
Fractures are usually defined in terms of their anatomical location:

• Fractures involving the orbital rim
  • Isolated orbital rim fractures
  • Contiguous with internal wall fracture
  • Zygomatic-maxillary complex fracture
  • Naso-ethmoidal fractures
  • Other pan-facial fracture i.e. Le Fort
• Fractures limited to the internal orbital skeleton
  • Blow-out fracture (floor and medial orbital walls most common)
  • Trap door fracture

Epidemiology

Orbital trauma accounts for 8-25% of all facial fracture presentations
BAOMS National Facial Injury Survey this has increased by 35% over a 10yr period
5-19% of patients presenting to A&E with isolated head injury with also have concomitant orbital injury

Clinical Features

Presentation ranges depending on force of mechanism:

• Orbital ecchymosis/ swelling/ laceration
• Enophthalmos/ Hypoglobus
• Bony step
• Surgical emphysema
• Reduced sensation to maxillary branch of trigeminal nerve (V2)

Eye signs:

• Subconjunctival haemorrhage without posterior boarder
• Ophthalmoplegia resulting in diplopia: Monocular v Binocular
• Reduced visual acuity &/ or colour vision
• Globe injury: abrasion, hyphema, detachment, rupture etc
• Relative afferent pupillary defect

Note trap door fractures in the paediatric population can be subtle and the only sign maybe restricted upward gaze or signs of the oculocardiac reflex: recurrent nausea & vomiting and bradycardia on looking up

Differential Diagnosis

Following conditions should be considered when assessing orbital trauma:

• Orbital Compartment syndrome
• Superior orbital fissure syndrome (SOF) (<1% of trauma)
  • Characterized by ophthalmoplegia, ptosis, proptosis of eye, dilation and fixation of the pupil, loss of corneal reflex and anaesthesia of the upper eyelid and forehead
  • Optic nerve not affected
• Traumatic optic neuropathy
  • Like SOFS with CNII involvement
  • Due to compression/ laceration of CNII through direct trauma or coupe/ contrecoup injury intracranially

Aetiology and Pathogenesis

Aetiology

• Dependent on mechanism of injury
  • Low velocity: floor and medial wall fractures
  • High velocity: rim and lateral wall fractures
• Most common mechanisms:
  • Assault 52%
  • Falls 31%
  • Sport injury 14%
  • Road traffic accidents 3%
• Don't forget domestic abuse and NAI

Pathogenesis

Hydraulic theory: The globe itself is struck directly from an object and is thrust posteriorly, transiently raising the pressure within the orbit causing the floor to ‘blow out’ into the maxillary sinus at its greatest point of weakness, above the infraorbital neurovascular bundle.

Buckling theory: Blunt trauma to the face transmits a pressure wave along the bone of the orbit causing them to “buckle” and crack.

Note in trap door fracture, due to bony compressibility and elasticity the fractured bone recoils back into position entrapping orbital contents notably fat and the inferior rectus muscle.

Investigations

Initial Assessment

Assessment as per ATLS guidelines

• 4-8% may have associated c-spine injury with roof and lateral walls showing higher association

Rule out sight threatening injury Full eye assessment:

• Visual acuity
• Visual Fields
• Occular movement
• Pupillary reflexes

Imaging

Plain film radiographs CT Orbits

Other

Ocular pressure

Management

• Conservative
• Surgical: if functional or aesthetic concerns

Prognosis and Complications

General:

• Depends on fracture pattern and incision made

Trapdoor:

• Operative time within 24hrs carries highest success rates in terms of recovery time and diplopia

Blowout:

• Extent of defect and volume loss
• Intraoperative techniques used: 3D printed, intraoperative navigation

Follow up:

• Standard surgical follow up for OMFS
• Ophthalmology f/u in case of strabismus correction