Pure Orbital Trapdoor Fractures in Adults: Tight Entrapment of Perimuscular Tissue Mimicking True Muscle Incarceration with Successful Results from Early Intervention

Abstract

Orbital trapdoor fractures (OTFs) entail entrapment of intraorbital soft tissues with minimal or no displacement of the affected bones and are almost exclusively seen in children. This article aimed to report the diagnosis and treatment of an OTF of the floor in an adult patient and to critically review the literature regarding the management aspects of this specific subset of orbital blowout fractures in adults. A 29-year-old man presented with limitations of vertical right eye movements owing to blunt orbital trauma. The patient mainly complained of double vision in upper gazes and some episodes of nausea. Neither floor defect nor significant bone displacement found on orbital computed tomography, while edema of inferior rectus muscle was apparent. The patient underwent surgical repair 5 days later; a linear minimally displaced fracture of the floor was recognized and complete release of the entrapped perimuscular tissues was followed. Within the first week postoperatively, full range of ocular motility was restored, without residual diplopia. This case was the only identified pure OTF over a 6-year period in our department (0.6% of 159 orbital fractures in patients >18 years). By reviewing the literature indexed in PubMed, a very limited number of either of isolated case reports or retrospective case series of pure OTFs has been reported in adults. Contrary to the typical white-eyed blowout fractures, the literature indicates that OTFs in adults seem to not always constitute absolute emergency conditions. Although such fractures need to be emergently/ immediately treated in children, in the absence of true muscle incarceration, adults may undergo successful treatment within a wider but either early or urgent frame of time. Adults frequently exhibit vagal manifestations and marked signs of local soft tissues injury.

Keywords: adult; blowout fracture; linear minimally displaced; muscle entrapment; orbital trapdoor fracture.

Fig. 1

(a) Restriction of upgaze eye movements, traumatic dilation of right pupil, hyphema (grade I), subconjunctival hemorrhage, and small superficial lacerations in right lower eyelid and forehead. (b) Hinge-like trapdoor (T1b) fracture of the right orbital floor, with entrapment of minimal orbital content.

Fig. 2

(a) A trapdoor-type fracture with entrapment of perimuscular tissue. (b) The orbital floor dissection and release of entrapped tissues completed. The bleeding branch of infraorbital artery (red arrow) and the infraorbital groove and nerve (white asterisk). (c) Placement of a collagen resorbable membrane. (d) The forced reduction test is applied and confirms the absence of extraocular muscle movement limitation. (e) Wound closure.

Fig. 3

(a) One week and (b–f) 1 year after surgery, full range of ocular motility was obviously repaired.

Fig. 4

Recommendations of timing for orbital fracture surgery according to Burnstine.

Fig. 5

Classification of the severity of computed tomography findings for inferior rectus injury by Yano et al.