Introduction: Orbital floor fractures occur commonly as a result of blunt trauma to the face and periorbital region. Orbital floor fractures with a “trapdoor” component allow both herniation and incarceration of contents through a bone defect into the maxillary sinus as the bone rebounds faster than the soft tissue, trapping muscle, fat, and fascia in the fracture site. In children, the fractured floor, which is often hinged on one side, tends to return toward its original anatomical position due to the incomplete nature of the fracture and elasticity of the bone. The entrapment of the inferior rectus muscle itself is considered a true surgical emergency—prolonged entrapment frequently leads to muscle ischemia and necrosis leading to permanent limitation of extraocular motility and difficult to correct diplopia. For this reason, prompt surgical intervention is recommended by most surgeons. In adults, true entrapment of the muscle itself is not as common because the orbital floor is not as elastic and fractures are more complete. Methods: We present an adult patient with an isolated orbital floor fracture with clinical and radiologic evidence of true entrapment of the inferior rectus muscle itself. Results: Despite the delayed surgical repair (4 days after the injury), the patient’s inferior rectus muscle function returned to near normal with mild upward gaze diplopia. Conclusions: Inferior rectus entrapment in adults may more likely be associated with immobilization of the muscle without total vascular compression/incarceration significant enough to lead to complete ischemic necrosis.
Magnetic Resonance Imaging of the Functional Anatomy of the Inferior Rectus Muscle in Superior Oblique Muscle Palsy