Residency · Residency · Oral Maxillofacial Surgery

Orbital Floor and Medial Wall Fractures

Overview

Orbital blowout fractures involve the orbital floor and/or medial wall without disruption of the orbital rim. They result from direct force to the globe or orbital rim that is transmitted to the thin orbital walls. The clinical significance lies in diplopia from extraocular muscle entrapment, enophthalmos from increased orbital volume, and infraorbital nerve injury. Timely diagnosis and appropriate surgical intervention prevent long-term functional and aesthetic sequelae.

Anatomy

Orbital Floor

The orbital floor is formed by the maxillary bone (orbital plate), zygomatic bone, and palatine bone. The thinnest portion is posteromedial (0.2-0.5 mm), which is the most common fracture site. It contains the infraorbital groove and canal carrying the infraorbital nerve (V2) and separates the orbit from the maxillary sinus.

Medial Orbital Wall

The medial orbital wall is formed primarily by the lamina papyracea of the ethmoid bone, which is extremely thin (0.2-0.4 mm). Additional contributions come from the lacrimal bone, frontal process of the maxilla, and lesser wing of the sphenoid. It separates the orbit from the ethmoid sinus and contains the anterior and posterior ethmoidal foramina (neurovascular bundles).

Orbital Contents

The orbit contains the globe, extraocular muscles (inferior rectus over the floor, medial rectus along the medial wall), and orbital fat (which serves as a cushion). The inferior orbital fissure lies at the posterolateral floor and represents the posterior boundary of surgical dissection. The optic canal at the posterior apex is an extreme caution zone. The periorbita (periosteum lining the orbit) contains and protects orbital contents.

Mechanism of Injury

Hydraulic Theory

A direct blow to the globe increases intraorbital pressure, and the thin walls (floor and medial wall) fracture as a "safety valve" to absorb pressure, protecting the globe from rupture by decompressing the orbit.

Buckling Theory

Direct force to the infraorbital rim transmits energy that buckles the thin orbital floor without requiring globe impact.

Clinical Reality

Both mechanisms likely contribute depending on the vector and energy of the impact. Common causes include fists, balls (baseball, tennis), falls, and motor vehicle collisions.

<image>Cross-sectional anatomy of the orbit showing the thin orbital floor overlying the maxillary sinus and the lamina papyracea of the medial wall overlying the ethmoid sinuses, with arrows indicating the hydraulic and buckling mechanisms of blowout fracture formation and the common sites of fracture (posteromedial floor and central lamina papyracea)</image>

Classification

By Location

Isolated floor fractures are the most common. Isolated medial wall fractures are less common and often missed on plain films. Combined floor and medial wall fractures increase orbital volume expansion and carry a higher risk of enophthalmos. Trapdoor fractures (greenstick or linear hinge fractures) occur when bone fractures and springs back into position, trapping orbital tissue, and are more common in children.

By Size

Small fractures (less than 50% of the floor) carry lower risk of enophthalmos. Large fractures (greater than 50% of the floor or greater than 2 cm2) carry higher risk of clinically significant enophthalmos. Defects extending to the posterior ledge or inferior orbital fissure are the most difficult to repair and carry the highest risk.

Clinical Presentation

Periorbital ecchymosis and edema are common. Diplopia occurs especially on upgaze (inferior rectus entrapment) or lateral gaze (medial rectus entrapment) and may be due to true muscle entrapment, herniated fat or connective tissue, or edema and hemorrhage. Enophthalmos (posterior displacement of the globe due to increased orbital volume) may be masked acutely by edema and becomes apparent as swelling resolves; more than 2 mm difference between sides is clinically significant. Infraorbital nerve hypoesthesia causes numbness of the ipsilateral cheek, upper lip, lateral nose, and anterior teeth. Restricted extraocular movements occur particularly in upgaze (floor fracture) or lateral gaze (medial wall). Subcutaneous emphysema produces crepitus around the orbit from air entering from the maxillary or ethmoid sinus, which is worsened by nose blowing. Nausea and vomiting occur as a vagal response to muscle entrapment, particularly in trapdoor fractures. Ipsilateral epistaxis may also occur.

White-Eyed Blowout Fracture (Pediatric Emergency)

The white-eyed blowout fracture is a trapdoor fracture with muscle entrapment in a child. It presents with minimal periorbital ecchymosis or swelling (the "white eye"), severe restriction of ocular motility, and nausea, vomiting, and bradycardia from the oculocardiac reflex. This requires urgent surgical repair within 24-48 hours, as delay leads to ischemic necrosis of the entrapped muscle.

Diagnosis

Clinical Examination

Visual acuity is always checked before any intervention. Pupillary response is assessed, with an afferent pupillary defect suggesting optic nerve involvement. Extraocular movements are tested in all directions of gaze. The forced duction test is performed under topical anesthesia by grasping the conjunctiva/sclera with forceps near the limbus and attempting to move the globe in the restricted direction -- a positive result (resistance to passive movement) indicates mechanical entrapment, while a negative result (free movement) indicates paresis, edema, or hemorrhage causing restriction. Hertel exophthalmometry measures globe position, with enophthalmos greater than 2 mm being significant. Infraorbital nerve sensation is tested.

Imaging

CT face (axial and coronal, 0.5-1 mm cuts) is the gold standard. Floor findings include herniation of orbital contents into the maxillary sinus, the "teardrop" sign, and fracture gap. Medial wall findings include disruption of the lamina papyracea with ethmoid sinus opacification. Entrapment appears as soft tissue tethered at the fracture site (the "trapdoor" or "missing muscle" sign). Orbital volume is measured and compared with the contralateral side. 3D reconstruction aids surgical planning. MRI is rarely needed but useful if CT is equivocal for muscle entrapment.

Management

Indications for Surgery

Absolute and urgent indications include trapdoor fracture with muscle entrapment (especially in children -- the white-eyed blowout), requiring repair within 24-48 hours, and nonresolving oculocardiac reflex. Relative indications (within 1-2 weeks) include diplopia with a positive forced duction test (mechanical entrapment) not resolving with observation, large floor defect (greater than 50% of the floor or greater than 2 cm2) predicting enophthalmos, enophthalmos greater than 2 mm (or anticipated based on defect size), CT showing significant soft tissue herniation into the sinus, and orbital volume increase greater than 1.5-2 cm3.

Observation (Non-Operative)

Observation is appropriate for small fractures (less than 50% of the floor) without entrapment or enophthalmos, diplopia from edema or hemorrhage that resolves within 1-2 weeks, and minimal soft tissue herniation on CT. Follow-up in 1-2 weeks reassesses diplopia, globe position, and forced duction test.

Surgical Technique

Timing

Urgent repair is performed for trapdoor fracture with entrapment (24-48 hours). Routine repair is performed within 2 weeks, allowing swelling to subside; beyond 2-3 weeks, fibrosis complicates repair.

Approaches

The transconjunctival approach uses an incision through the conjunctiva with preseptal or retroseptal dissection. It carries lower risk of ectropion or scleral show, can include a lateral canthotomy for extended exposure, and is preferred by most surgeons for aesthetic outcome. The subtarsal approach uses a skin incision 5-7 mm below the lash line, providing direct exposure of the infraorbital rim but with slightly higher risk of lower eyelid malposition. The subciliary approach uses an incision 2 mm below the lash line and carries the highest risk of ectropion, making it less commonly used. The transantral (Caldwell-Luc) approach accesses the floor through the maxillary sinus from below and is rarely used as the primary approach but may supplement floor repair. The endoscopic-assisted transnasal approach is used for medial wall fractures.

Repair Steps

The procedure begins with approach and exposure of the infraorbital rim and orbital floor, followed by identification of the fracture margins (360 degrees). Herniated orbital tissue is reduced back into the orbit, and entrapped tissue is released with gentle, atraumatic manipulation. The posterior ledge of the defect is identified (critical for implant support), and an implant is placed to reconstruct the floor or wall. The implant must rest on stable bone at all margins. A forced duction test is performed after repair to ensure no iatrogenic entrapment, and the incision is closed.

Implant Materials

Titanium mesh is strong, moldable, radiopaque (visible on CT), and can be pre-bent or patient-specific. It is the most commonly used material for large defects but carries risk of globe injury from sharp edges and can be difficult to remove if needed. Porous polyethylene (Medpor) allows tissue ingrowth, is non-resorbable and radiolucent, is good for moderate defects, but is difficult to remove once vascularized. Resorbable plates (PLLA, PGA/PLA) resorb over 12-24 months, are suitable for small to moderate defects, are ideal in pediatric patients, but carry risk of late inflammatory reaction during resorption. Autogenous bone (calvarial, iliac crest, maxillary sinus wall) is biocompatible with no foreign body reaction but has donor site morbidity, unpredictable resorption, and is less commonly used in modern practice. Nylon (Supramid) sheet is thin and flexible for small defects but provides no structural support for large defects.

<image>Intraoperative view through a transconjunctival approach showing the orbital floor defect with herniated orbital fat and periorbita prolapsing into the maxillary sinus, followed by reduction of the herniated tissue and placement of a preformed titanium mesh implant spanning the defect with the posterior ledge serving as the key support point</image>

Outcomes

Diplopia resolves in 80-90% of cases when repaired within 2 weeks and appropriately indicated. Enophthalmos is well-corrected when orbital volume is accurately restored. Infraorbital nerve recovery occurs in 70-90% within 6-12 months. Persistent diplopia risk is 5-15% from scar, fibrosis, or inadequate release.

Complications

Persistent or worsened diplopia may result from implant malposition, incomplete release, or scar contracture. Enophthalmos indicates under-correction of orbital volume. Exophthalmos indicates over-correction from an implant that is too large or too anteriorly placed. Ectropion or lower eyelid retraction is approach-related, especially with the subciliary approach. Infraorbital nerve injury may occur iatrogenically during dissection. Implant malposition or migration results from inadequate support at the posterior ledge. Infection is uncommon but may require implant removal. Orbital hemorrhage (retrobulbar hematoma) is rare but sight-threatening, requiring emergent lateral canthotomy and cantholysis. Vision loss is rare and may result from optic nerve compression, retrobulbar hematoma, or direct injury.

Clinical Pearls

Visual acuity should always be checked before any orbital surgery to document a baseline. The white-eyed blowout fracture in children is a surgical emergency, and repair should not be delayed for swelling to resolve. The forced duction test is the most important clinical tool for differentiating mechanical entrapment from edema-related motility restriction. When in doubt about whether to operate, CT volumetric analysis should be obtained, as orbital volume increase greater than 1.5 cm3 predicts clinically significant enophthalmos. The posterior ledge is the key to successful implant placement -- if it cannot be identified, the implant has no support and will fail. Over-correction by placing too large an implant should be avoided because exophthalmos is difficult to manage. A forced duction test should always be performed after implant placement, as iatrogenic entrapment is an avoidable complication. Lateral canthotomy and cantholysis for retrobulbar hematoma is a sight-saving procedure that every OMFS resident must know by heart.

References

• Burnstine MA. Clinical recommendations for repair of orbital floor fractures. Curr Opin Ophthalmol. 2003.
• Egbert JE, et al. Pediatric orbital floor fractures: direct extraocular muscle involvement. Ophthalmology. 2000.
• Boyette JR, et al. Management of orbital fractures: challenges and solutions. Clin Ophthalmol. 2015.
• Ramesh S, et al. Systematic review of orbital floor repair materials. J Craniofac Surg. 2016.
• Dubois L, et al. Indications for surgical repair of orbital floor fractures: a review. J Craniomaxillofac Surg. 2015.
• Ellis E, Tan Y. Assessment of internal orbital reconstructions for pure blowout fractures. J Oral Maxillofac Surg. 2003.

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