Correlation between changes of medial rectus muscle section and enophthalmos in patients with medial orbital wall fracture

Background: Enophthalmos is the most distressing and common complication of the blow-out fracture. In spite of well-established indications for early operative repair of orbital fracture, 7-10% of patients treated non-operatively develop enophthalmos. There have been reports on the correlation between changes of orbital bone and enophthalmos; however, there is no report on muscle changes in computed tomography (CT) in medial blow-out fracture. The present authors have documented the correlation between change of medial rectus muscle and enophthalmos using CT scan in medial blow-out fracture patients. Methods: In this study (from January 2001 to December 2006) of 340 patients diagnosed with medial blow-out fracture, 24 patients were treated non-operatively. Nine patients (Group 1) have over 2-mm enophthalmos and 15 patients (Group 2) have enophthalmos less than 2 mm. The height-to-width (H-W) ratios of medial rectus muscle were measured in coronal views, and the size of defects were measured in coronal and axial views in CT. Hertel's exophthalmometry was measured on both eyes for all patients. Results: The H-W ratios measured in the affected orbits were statistically significant between the two groups (p < 0.0001). However, the size of defect is not related with enophthalmos in two groups statistically (P = 0.421). Conclusion: These results mean that the H-W ratio of medial rectus muscle in coronal views of CT is a useful parameter to predict enophthalmos, and whether H-W ratios of medial rectus muscle over 0.7 need surgical correction. (C) 2008 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.