Orbital Fracture

Overview

Orbital fractures result from blunt (or, less commonly, penetrating) trauma to the orbit, most often involving the thin orbital floor or medial wall — the "blowout" pattern — since these are the weakest bony walls of the orbit. Fractures can be isolated (involving only the floor or wall) or occur as part of more complex craniofacial trauma, and management ranges from observation to urgent or elective surgical reconstruction depending on the specific pattern and associated findings.

Epidemiology & Risk Factors

Orbital floor fractures are increasingly common and result from assault, falls, sports injuries, and road traffic accidents, among other causes.² Children represent a distinct and clinically important population: their more elastic, less calcified orbital bone predisposes to a specific fracture pattern — the trapdoor fracture — in which the bone fractures, herniates orbital tissue (including extraocular muscle), and then springs back into near-normal position, trapping the herniated tissue with a "hinge" mechanism rather than leaving an obvious persistent bony defect.³

Pathophysiology

Blunt trauma to the globe or orbital rim transmits force through the incompressible orbital contents (analogous to a hydraulic mechanism), and this force is released through fracture of the weakest bony walls — most commonly the orbital floor, given its thinness relative to the orbital rim and other walls. In adults, this typically produces a fracture with persistent bony displacement, allowing orbital fat and sometimes extraocular muscle to herniate into the maxillary sinus. In children, the more elastic, pliable bone characteristic of the pediatric skeleton allows a "trapdoor" mechanism: the bone fractures, opens briefly to allow tissue (often the inferior rectus muscle) to herniate through, then springs back, mechanically entrapping the herniated tissue at the fracture site — a mechanism that can cause severe muscle ischemia and dramatic clinical findings (marked restriction, pain, and sometimes an oculocardiac reflex with bradycardia, nausea, and vomiting) despite an often unremarkable external appearance, hence the term "white-eyed blowout fracture."³

Clinical Presentation

Presentation ranges widely based on fracture pattern and severity: patients may present with periorbital edema and ecchymosis, diplopia (from either extraocular muscle entrapment or direct muscle injury/edema), infraorbital nerve hypoesthesia (from involvement of the infraorbital canal traversing the orbital floor), enophthalmos (globe retrusion from expanded orbital volume, more apparent once initial swelling resolves), and, in pediatric trapdoor fractures with entrapment, severe pain and dramatically restricted motility, sometimes with minimal or absent external bruising or swelling — a presentation that can be misleadingly reassuring if not carefully evaluated.³

Exam Findings

• Periorbital ecchymosis, edema, and subcutaneous emphysema (from communication with the paranasal sinuses), common findings in adult orbital floor fractures²
• Diplopia, present in roughly half of isolated orbital floor fracture cases in one large adult surgical series²
• Restricted extraocular motility, particularly in upgaze, from either mechanical entrapment or direct muscle/perimuscular tissue injury
• Infraorbital nerve hypoesthesia, a less common but important finding reflecting canal involvement²
• On CT imaging, the "tear-drop sign" — a teardrop-shaped soft tissue density herniating through the orbital floor into the maxillary sinus — is a classic radiographic indicator of tissue (often inferior rectus) entrapment, particularly relevant in suspected pediatric trapdoor fractures³
• Positive forced duction testing, helping confirm true mechanical restriction (entrapment) versus a purely neurogenic or edema-related motility deficit

Differential Diagnosis

• Isolated extraocular muscle contusion or cranial nerve palsy from trauma without a structural fracture (distinguished by imaging)
• Traumatic optic neuropathy (a distinct, vision-threatening traumatic complication requiring its own urgent recognition, separate from motility-restricting orbital wall fractures)
• Orbital hemorrhage/hematoma causing restriction and proptosis without an underlying fracture
• Zygomaticomaxillary complex fracture or other complex craniofacial fracture pattern involving, but not isolated to, the orbital floor

Management

Diagnosis relies on clinical exam (motility assessment, forced duction testing, sensory exam, globe position) combined with CT imaging of the orbits, which characterizes fracture location, size, and the presence or absence of soft tissue/muscle herniation or entrapment. In isolated adult orbital floor fractures, standardized CT-based indication criteria — including the RF index (fracture defect size relative to total orbital floor length), MH index (maximum height of periorbital tissue herniation), and MRI index (inferior rectus muscle involvement/distortion) — have been used to guide the decision between surgical and conservative management, since the choice between these approaches is the key factor determining therapeutic outcome.²

In children, surgical timing for confirmed extraocular muscle entrapment is a genuine emergency rather than a routine, schedulable procedure: a combined cohort study and systematic review found that surgical intervention within 24 hours of injury was significantly associated with better postoperative ocular motility outcomes compared with delayed surgery, and that patients treated within 8 hours specifically achieved excellent recovery (Hess area ratio exceeding 85%, no residual diplopia); this urgency reflects the risk of irreversible ischemic muscle damage the longer entrapment persists.¹ Notably, pediatric patients without true extraocular muscle entrapment (only soft tissue entrapment, without a sustained oculocardiac reflex) generally improved with conservative, non-operative management over an average of about 7 weeks, underscoring that not every pediatric orbital fracture requires urgent surgery — accurate distinction between true entrapment and simple soft tissue involvement is essential.¹

For adults undergoing surgical reconstruction, various graft materials (autologous cartilage, including nasoseptal or auricular conchal cartilage, as well as alloplastic implants) are used to repair the orbital floor defect, with nasoseptal cartilage reconstruction reported as a highly effective and safe method in one single-center series using standardized radiological indication criteria for surgical selection.²

Complications

• Persistent diplopia, particularly if entrapment is not addressed promptly or if muscle injury is severe
• Enophthalmos from inadequately repaired or unrepaired orbital volume expansion
• Ischemic muscle damage and permanent motility restriction from prolonged, unrecognized extraocular muscle entrapment, particularly in pediatric trapdoor fractures
• Infraorbital nerve hypoesthesia, sometimes persistent even after successful fracture repair
• Oculocardiac reflex (bradycardia, nausea, vomiting, syncope) as an acute, potentially dangerous manifestation of severe entrapment, particularly in children, requiring prompt recognition and urgent surgical release

Clinical Pearls

• The "white-eyed blowout fracture" in children can present with minimal external signs but severe muscle entrapment — do not let a benign external appearance provide false reassurance³
• Surgical repair of confirmed pediatric extraocular muscle entrapment within 24 hours (ideally within 8 hours) significantly improves ocular motility outcomes compared with delayed surgery¹
• Not all pediatric orbital fractures require emergency surgery — soft tissue entrapment without sustained oculocardiac reflex often improves with conservative management alone¹
• The "tear-drop sign" on CT is a classic indicator of tissue herniation/entrapment through the orbital floor, particularly relevant in suspected pediatric trapdoor fractures³
• Standardized radiological indices (defect size, herniation height, muscle involvement) support surgical decision-making in adult isolated orbital floor fractures²

Common Pitfalls

• Reassuring a child with orbital trauma based on minimal external bruising without carefully assessing motility and considering entrapment
• Delaying surgical referral for confirmed pediatric extraocular muscle entrapment, risking irreversible ischemic damage and permanent motility deficit
• Failing to distinguish true muscle entrapment from simple soft tissue involvement, potentially leading to unnecessary emergency surgery in cases that would resolve with observation
• Overlooking infraorbital nerve hypoesthesia as an important associated finding requiring documentation and patient counseling
• Missing an associated traumatic optic neuropathy while focused on the motility-restricting fracture itself