Mandibular symphysis graft versus iliac cortical graft in reconstructing floor in orbital blow out fracture: A comparative study

The purpose of this study was to clinically and radiologically assess and compare the outcome of internal orbital reconstruction with an iliac bone graft and mandibular symphysis graft in orbital blow out fractures.

Eight consecutive patients with unilateral orbital blow out fractures were enrolled in this prospective study. CT scan imaging and volumetric assessment of the orbit was done for all patients using GE Discovery VCT Workstation 4.4. Patients with defect of area less than 2 cm(2) and orbital volume expansion of less than 4.7 cm(3) were treated with mandibular symphysis graft, in contrast the others were treated with a medial cortical graft from the anterior ilium. At each follow-up visit, globe posture, diplopia, and eye movements were assessed. Coronal and sagittal computed tomography and volumetric assessment were used to observe graft posture, bone defects and contour.

Group I cases showed that orbital volume changes of less than 2cm(3) can be effectively reduced. Group II cases showed that orbital volume changes of more than 4.5 cm(3) could not be effectively restored in spite of using large iliac graft. All eight patients had satisfactory correction of hypoglobus. Diplopia and ocular motility restriction resolved in all affected patients post operatively between 4(th) day and 2(nd) week. At 3-month follow-up, computed tomography demonstrated that the middle section of the orbital floor was well elevated in all 8 orbits. All grafts were still in situ, with density measured in Hounsfield units revealed that the Mandible Symphyseal graft was denser.

The mandibular symphysis graft is a good, simple reconstructive option in small orbital floor defects with orbital volume change less than 4.71 ml. In larger defects with huge orbital volume changes that require more volume of graft, iliac graft is useful albeit, perfect, volumetric restoration is not always possible.