Association of Absent or Trace Fluid in the Maxillary Sinus and Inferior Rectus Muscle Entrapment in Patients With Orbital Floor Fracture.

Inferior rectus (IR) entrapment requires urgent surgical intervention in patients with traumatic orbital floor fracture (OFF). We evaluated 47 patients who underwent CT showing acute OFF, 10 of whom had surgically confirmed entrapment. Absent or trace dependent fluid in the ipsilateral maxillary sinus had sensitivity of 40% and specificity of 95% for entrapment. In comparison, sensitivity and specificity were 80% and 78% for IR thickening and 70% and 59% for sinus herniation of orbital contents.