Osteoplastic Reconstruction of Post-enucleatic Microorbitalism

Background Patients who have undergone enucleation during infancy due to retinoblastoma can develop microorbitalism due to the decreased growth stimulation from the eyeball and the surrounding soft tissues. Anatomically, the orbit consist of parts of the frontal bone superiorly, the maxilla inferiorly, the ethmoid bone medially, and the zygoma laterally. Considering the possibility of surgically expanding the orbit using tripod osteotomy, in this study we conducted tripod osteotomy on adult patients with microorbitalism of retinoblastoma. Methods Tripod osteotomy was conducted to expand the orbital volume in adult patients with microorbitalism due to enucleation in infancy for retinoblastoma. The orbital volume was measured using the Aquarius Workstation ver. 4.3.6 and the orbit width was measured with preoperative and postoperative 3-dimensional facial bone computed tomography (CT) imaging. Preoperative and postoperative photographs were used to visualize the difference produced by the surgery. Results The orbital volume of the affected side was 10.3 $cm^3$ before and 12.5 $cm^3$ after the surgery, showing an average increase in volume of 2.2 $cm^3$ (21.4%). The increase in the obital width was confirmed by the preoperative and postoperative 3-dimensional facial CT images and aesthetic improvement was observed by the preoperative and postoperative photographs. Conclusions Tripod osteotomy, which realigns the orbital bone, zygoma, and maxilla, is used to correct posttraumatic malunion as well as non-traumatic congenital abnormalities such as that seen in facial cleft. We applied this procedure in microorbitalism secondary to enucleation for retinoblastoma to allow orbital expansion and correct asymmetry.