"Trap Door" Orbital Floor Fractures in Adults: Are They Different from Pediatric Fractures?

Abstract

Background: "Trap door" orbital floor fractures are usually seen in children. In the linear fracture type, a break occurs in the bones of the orbital floor that permits orbital tissue to prolapse into the fracture site during fracture formation. The bony fragments of the fracture then return to their original position, entrapping the prolapsed orbital tissue. In the hinged fracture type, the fractured part of the floor is minimally displaced into the maxillary sinus and acts as the hinge of a "swinging door" entrapping the orbital tissue.

Methods: We report on a series of 10 adult patients with hinged orbital floor fractures.

Results: The mean patient age was 35 years. Seven patients had a pure orbital floor fracture and the remaining 3 patients had fractures of both the orbital floor and the inferior orbital rim. All 10 patients had diplopia in the upgaze. None of the patients had signs of the oculocardiac reflex. None of the CT scans showed a "tear-drop" sign. However, the sagittal CT scans showed evidence of entrapment of the inferior rectus. All patients had a small area of a slightly depressed orbital floor at the site of entrapment, without a bony defect. All patients underwent surgery through an infraorbital incision and a titanium mesh was used in all patients. There were no postoperative complications. All patients regained full range of motion of the globe.

Conclusion: This is the first series in the literature that reports on the characteristics and outcome of trap door orbital floor fractures in adults.

Fig. 1.

A coronal cut in the orbit showing the entrapment by the hinged fracture. There is a gap; but no defect in the orbital floor.

Fig. 2.

A sagittal cut in the orbit showing the loss of the normal orientation of the inferior rectus muscle because of its entrapment in the “hinge” in hinged orbital floor fractures.

Fig. 3.

A demonstration of mesh application in a patient with an orbital rim fracture and an adjacent anterior floor trap door hinged blowout fracture. The patient fell from a significant height and also sustained a scalp laceration and a depressed skull fracture. This patient is a recent patient and is not included in the series, but is shown here to demonstrate the surgical technique. Combined plastic surgery and neurosurgery was done. A, Preoperative appearance with limitation of supraduction of the right orbit. B, Using a trans-conjunctival approach, the orbital rim fracture is subperiosteally dissected, and the entrapped orbital tissue is identified. C, The entrapped orbital tissue is released, the orbital rim fracture is reduced, and a titanium mesh is used to stabilize the reduced orbital rim (using 1.5 mm self-tapping screws) as well as to support the orbital floor. D, Immediate postoperative view showing the recovery of a normal supraduction of the eye (with complete resolution of the diplopia).

Fig. 4.

A case demonstration of a pure orbital floor trapdoor fracture. A, Preoperative sagittal CT scan showing a slightly depressed orbital floor (with no orbital floor defect and no tear drop sign) and entrapment of the inferior rectus. Note the loss of the normal orientation of the inferior rectus muscle (compare with Fig. 2). There is also entrapment of air in the orbital cavity just above the depressed orbital floor. B, Preoperative coronal CT scan view. Note the absence of the tear drop sign despite the presence of blood in the maxillary sinus. C, Preoperative 3D CT scan showing the intact orbital rim. D, Postoperative CT Scan showing the titanium mesh used to augment the area of depressed orbital floor after releasing the entrapped inferior rectus muscle. Note the receovery of the normal orientation of the inferior rectus muscle (compare with A).

Fig. 5.

Demonstration of the post-operative clinical result in the patient shown in Figure. 4. A, Postoperative clinical photograph at 1 week demonstrating the incision and the minimal edema/ecchymosis. B, There is no more diplopia with full orbital movements in the upward gaze. C, The infraorbital scar is linear at 7 months after surgery.

Fig. 6.

A case demonstration of an impure (orbital rim and floor) fracture. A, Preoperative clinical photograph showing the severe periorbital soft-tissue injury and subcutaneous hematoma. B, Preoperative 3D CT scan showing the orbital rim fracture. C, Preoperative sagittal CT scan view showing the adherence of the inferior orbital tissue at the anterior aspect of the orbital floor (adjacent to the orbital rim fracture). The patient had diplopia on the upward gaze and a positive forced duction test. D, Preoperative coronal CT scan view showing the extensive periorbital hematoma and a hinged (Gerbino type II) fracture in the orbital floor. E, Postoperative 3D CT scan showing the reduced orbital rim fracture fixed with the titanium mesh which also extended to the area of depressed floor similar to the demonstration shown in Figure 3. F, Postoperative CT scan showing the titanium mesh in place. G, Postoperative clinical view showing the full orbital range of motion in the upward gaze.