Hypertropia and the posterior blowout fracture: Mechanism and management.

OBJECTIVE: To better understand the pathophysiology and proper management of a subgroup of patients with orbital blowout fracture which manifests by a vertical diplopia and hypertropia on the affected side.

PATIENTS AND METHODS: This report is based on a series of ten consecutive patients with orbital floor blowout fractures who had diplopia and hypertropia on the affected side. All patients were followed through at least 13 days of conservative care. Computed tomography demonstrated a characteristic depressed fracture of the posterior orbital floor extending to the posterior wall of the maxillary sinus in all patients. In many patients, the inferior rectus looped inferiorly and then rose to contact the globe at a steep angle. Diplopia did not spontaneously resolve in any patient. At surgery, the orbital contents were elevated to the posterior extent of the fracture, and the floor defects were bridge. Patients were followed for resolution of diplopia.

RESULTS: Eight patients had resolution of the hypertropia and diplopia within 2 months of surgery, and two patients had residual diplopia in extreme downgaze but were significantly improved.

CONCLUSIONS: When hypertropia and vertical diplopia are noted after orbital trauma, a posterior blowout fracture should be suspected. In these patients, infraduction may be diminished due to changes in the effective origin and insertion of the inferior rectus muscle. The diagnosis of a posterior blowout fracture should be supported by characteristic findings on computed tomography. If the motility abnormality persists for 10 to 14 days, posterior orbital exploration and fracture repair should be undertaken.