Imaging of orbital floor fractures.

The aim of this study was to compare the efficacy of plain films and computed tomography (CT) in defining inferior orbital fractures and any muscle involvement. Forty-four patients with final diagnosis of orbital floor fractures in the period 1990-94 were retrospectively studied. Computed tomography was performed in 28 patients, 20 being direct coronal acquisitions and eight being fine axial acquisitions with coronal reconstructions. Water's view radiographs were performed in 34 patients. Fourteen fractures on plain films were associated with soft tissue opacities to suggest inferior rectus (IR) muscle involvement, but only two required surgical elevation of the orbital floor. The remaining patients were successfully treated conservatively. Three patients had IR entrapment on direct coronal CT, all requiring surgical elevation of the orbital floor. Seven patients had IR muscle displacement on direct coronal CT and all had conservative management. In four patients with axial acquisition and coronal reconstructions, the CT images were of inadequate quality to determine the presence or absence of a fracture. One patient who had no IR muscle involvement identified on reconstructed coronal CT required surgical elevation of the orbital floor on clinical grounds. We conclude that: (i) soft tissue opacities on plain films are not an accurate indicator of clinically significant IR involvement; (ii) axial CT is not efficacious in detection of fractures or IR involvement; and (iii) direct coronal CT is the most efficacious imaging modality.