Primary Orbital Fracture Repair

Key points

  • Predictable outcomes of complex orbital fracture patterns may be achieved by a structured and evidence-based approach.

  • Full anatomic and physiologic assessment of the fracture pattern using computed tomographic data and quantitative orthoptic analysis allows for precise planning of the surgical technique.

  • Preseptal transconjunctival access with transcaruncular extension and lateral swinging lid technique allows for ultimate exposure of the fracture complex.

  • Incarcerated orbital tissues must be identified and planned for released without surgical duress to the musculature.

  • Surgical momentum is progressing toward patient-specific implants for larger and more strategic fracture patterns. Medial and floor reconstruction to the apex can now be achieved.

Introduction

The nature of the problem

Fracture patterns of the anatomic orbit are common in contemporaneous oral and maxillofacial practice and exist in isolation or in concert with adjacent skeletal components. There is variance in complexity according to volume of energy transfer, and clinical heterogeneity in presentation because of soft tissue involvement, some of which may be vision threatening. Predicable outcomes therefore depend on prompt clinical diagnosis augmented by full anatomic description of the fracture configuration in conjunction with formal physiologic assessment. This full clinical data set then will inform prompt surgical management followed by evidence-based indications for surgery, approach, materials and methods used, together with prognostication to manage both surgeon and patient expectation.

Changes within the UK acute trust infrastructure have led to the adoption of major trauma centers, of which the Royal London Hospital was the prototype example, with 30 years of dedicated multidisciplinary trauma experience. This multidisciplinary trauma experience has led to proven increased survival rates in complex high-energy injury mechanisms, and greater survival rates resulting in higher numbers of complex facial injuries coming to surgery. The social demographic of East London, with a substantial history of criminal and even political violence, is well known. The UK Crime statistics indicate 30,000 violent crimes reported per year in East London, representing 19.5% of all crimes reported . The map of London in Fig. 1 demonstrates the significantly increased crime levels in the region.

Fig. 1
Map of London demonstrating the significantly increased crime levels in the region. RLH, Royal London Hospital.

Surgical pathologic condition

Anatomic classification

Classically, orbital fracture patterns were described as either pure or impure. Impure fractures follow failure of the orbital rim, which can either be localized to the inferior orbital rim and associated with the orbital floor or propagate to the orbit from an adjacent facial bone fracture ( Table 1 ).

Table 1
Classification of orbital floor and wall fractures
Pure Impure Roof
Floor Segmental lower-orbital rim Isolated
Medial wall Nasomaxillary Craniofacial
Zygomatic
Maxillary
Nasoethmoid

The distinction of pure and impure of course has surgical significance but seems to be less important in the association with ocular damage, this born out clinically and by finite element analysis, which illustrates that the failure threshold for globe rupture is less than that of bone.

The surgical principle is to convert impure to pure orbital injuries and then treat the floor and medial walls accordingly. The size of the defect and position have both profound influence on surgical complexity and prognostic implications in terms of both aesthetics and function. Most surgeons will agree that fractures toward the posterior floor and upper medial third are more technically challenging and take longer to return to normal function postoperatively. Ahmad proposed a quantitative assessment of orbital fractures by splitting the floor and medial wall into separate thirds, as well as quantifying fracture severity in the rest of the facial skeleton, with recognition of the presence or absence of the posterior medial ledge. Jaquiery classified orbital fractures into 5 types according to surgical complexity, focusing on the size of defect and presence or absence of the posterior bone ledge medial to the infraorbital nerve, which facilitates anatomic dissection, and in addition, seating of the implant ( Table 2 ).

Table 2
Jaquiery classification
Stage Size of Defect (cm 2 ) Bone Ledge Medial To Orbital Fissure
I 1–2 Yes
II >2 Yes
III >2 No
IV Entire orbital floor/medial wall No
V Extension to roof No

Functional classification

Facilitation of binocular single vision requires the integration of a complex neuromuscular system involving 4 cranial nerves and 6 extraocular muscles working in a highly coordinated syncytium. The nuclei of the cranial nerves supplying these muscles are linked by the medial longitudinal fasciculus, which allows coordination with integration of the vestibular nerve. Disruption by intracranial damage can cause internuclear ophthalmoplegia. The muscles themselves are easily damaged or trapped in certain fracture patterns ( Table 3 ).

Table 3
Neurology of the orbit
Structure Function Pathologic Conditions
Oculomotor nerve
  • Motor to

    • Medial rectus

    • Inferior rectus

    • Superior rectus

    • Inferior oblique

  • Entrapment

  • Contusion

  • Snagging

  • Tearing

  • Neuromuscular

Trochlear nerve Motor to superior oblique
  • Contusion

  • Snagging

  • Tearing

  • Neuromuscular

Abducent nerve Motor to lateral rectus
  • Contusion

  • Snagging

  • Tearing

  • Neuromuscular

Medial longitudinal fasciculus Linking all intracranial nuclei
  • Head injury

  • Neurologic pathologic condition

Fracture progression is influenced by the mechanism and biomechanics of the orbit itself. In paediatric mechanisms, energy transfer commonly produces a linear fracture resulting herniation of the orbital contents with entrapment due to the elastic biomechanical nature of the orbital floor. Linear fracture pattern may occur with comparatively low-energy transfer and produce the so-called white-eye blowout fracture, which could be initially missed in accident and emergency departments. One of the symptoms is persistent postinjury nausea and vomiting, so a computed tomographic (CT) scan of the brain could incidentally expose the orbital fracture. Nevertheless, experience shows that CT scan is not always conclusive, and a trapdoor fracture could be missed easily.

Indications for surgery

The decision to operate follows comprehensive assessment of the fracture pattern in concert with the patient, in which clinical, medical, anatomic, and functional considerations are supported by objective evidence from detailed imaging and formal quantified orthoptic examination. With the exception of a vision-threatening condition that demands immediate surgical treatment, all indications are relative. Ultimately, it is a balanced decision between the surgeon and the patient according to individualization of the risk-benefit ratio.

Restoration of anatomy

The aesthetic form of the orbit involves harmony between the soft and hard tissues.

The orbital floor and medial wall have several key strategic landmarks, which maintain globe position. These landmarks have been described by Hammer with reference to the posterior medial bulge ( Fig. 2 ). Note the normal left side in this low orbital axial view (blue arrow) and the fractured right side (right arrow), and the sigmoid nature of the floor in sagittal view ( Fig. 3 ). In this view, the blue zone maintains the vertical height of the globe, and the sigmoid green zone maintains projection.

Fig. 2
Axial CT scan at the level of the mid to lower orbit demonstrating Hammer’s key area ( blue arrow ). The fracture of the medial orbital wall compromises this ( red arrow ).

Fig. 3
Sagittal view of an intact orbit. Fractures involving the posterior and middle third of the orbital floor ( green line ) reduce globe projection; fractures of the anterior third ( blue line ) contribute to vertical discrepancy (hypoglobus).

The concept of orbital volume remains but is, of course, related to the geometry of the bone orbit. It should also be appreciated that the volume comprises all the orbital adnexae, which includes fat and muscle, but in addition, the globe itself.

Restoration of function

In order to facilitate free movement of the globe, any trapped tissue within linear fractures, or physical limitation by sharp bone fragments, needs to be removed.

Primary orbital trauma decision making

Decision making for Orbital Reconstruction should follow a logical and stereotypical process which includes appraisal of physical findings, and assessment of hard and soft tissue subunits, with didactic surgical treatment planning ( Fig. 4 ).

Fig. 4
Pathway and decision making in orbital trauma.

Emergency management

The orbit is described as a 4-walled pyramid contained by the orbital septum constrained by the lateral and medial canthal tendons, making the orbital contents vulnerable to compartment syndrome. Although an expanding retrobulbar hematoma is recognized, it must also be appreciated that intraorbital surgical emphysema, cerebrospinal fluid, and displaced bone fragments can be implicated.

Although medical management in the form of acetazolamide, mannitol, and hydrocortisone is described, lateral cantholysis in a timely manner is frequently vision saving.

Fig. 5 demonstrates an axial view of a medial wall fracture (red arrows) and a retrobulbar hematoma (blue arrows).

Fig. 5
Axial view of a medial wall fracture ( red arrows ) and a retrobulbar hematoma ( blue arrows ).

Physical signs of ocular compartment syndrome

  • Ophthalmoplegia

  • Tense and proptosed globe

  • Loss of red vision

  • Loss of visual acuity

  • Escalating pain

The risk of ocular damage in facial injuries has been described many times, and the famous mnemonic device of BAD ACT has been constructed to raise awareness:

B: Blow out

A: Acquity

D: Diplopia

A: Amnesia

CT: Comminuted trauma

These injuries can frequently be difficult to assess because of acute periorbital swelling or may be masked by substance or alcohol abuse and a lowered level of consciousness. High-energy mechanism injured patients with multisystem injuries may mask orbital injuries that are not life threatening ( Box 1 ).

Box 1
Risk factors for ocular involvement

  • Significant volume of trauma

  • Orbital fracture: increased probability with increasing size

  • Multiple fractures: particularly involving orbital cancellous bone

  • Impaired consciousness: pain is less of a feature

Diagnosis, quantification, and prognostication of fracture pattern

CT scan analysis is central to diagnosis and planning treatment as well as to prognostication.

The sequential analysis of axial-coronal-sagittal formatted scans with measurement of bone loss and even angulation of fragments can be conducted near the patient with modern PACS systems.

Interpretation will influence the incision with the need for lateral and medial extensions to achieve predictable access, which materials to reconstruct, and risks to anatomic structures.

CT scans can also be interrogated to both diagnose and prognosticate functional deficits because of muscular involvement. The classic description of a trapdoor fracture typically seen in the pediatric or adolescent, otherwise known as the white-eye blowout fracture, is an example.

The CT scans visualized in coronal format demonstrate the region (blue square) of the fracture that is typically close to the infraorbital canal (green arrow) ( Fig. 6 ).

Fig. 6
Coronal CT scan demonstrating region of an orbital floor fracture with herniation of contents ( blue zone ); the infraorbital canal is demonstrated by the green arrow.

The sagittal view illustrates the small size of the fracture (T), and soft tissue windows may distinguish between muscle and fat prolapse ( Fig. 7 ).

Fig. 7
Sagittal fracture of the orbital floor trapdoor fracture T.

This fracture pattern is not exclusively seen in young patients and is not always confined to the floor. The author has seen this pattern in older patients and affecting the medial wall involving medial rectus and superior oblique.

The scan, soft tissue windows, coronal format demonstrates the fracture (blue arrow) and the superior oblique (red arrows) ( Fig. 8 ).

Fig. 8
Coronal CT scan. Soft tissue windows demonstrating a high medial wall fracture ( blue arrow ) with distortion and incarceration of superior oblique ( red arrows ).

CT scans may also support orthoptic diagnosis and prognosticate on the possibility of postoperative functional defect. Orthoptic examination is mandatory for all clinical diagnoses of diplopia and will help prognosticate ( Table 4 ).

Feb 28, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Primary Orbital Fracture Repair
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