Reconstruction using ‘triangular approximation’ of bone grafts for orbital blowout fractures

Abstract There are many orbital wall reconstruction materials that can be used in surgery for orbital blowout fractures. We consider autogenous bone grafts to have the best overall characteristics among these materials and use thinned, inner cortical tables of the ilium. A bone bender is normally used to shape the inner iliac table to match the orbital shape. Since orbital walls curve three-dimensionally, processing of bone grafts is not easy and often requires much time and effort. We applied a triangular approximation method to the processing of bone grafts. Triangular approximation is a concept used in computer graphics for polygon processing. In this method, the shape of an object is represented as combinations of polygons, mainly triangles. In this study, the inner iliac table was used as a bone graft, and cuts or scores were made to create triangular sections. These triangular sections were designed three-dimensionally so that the shape of the resulting graft approximated to the three-dimensional orbital shape. This method was used in 12 patients with orbital blowout fractures, which included orbital floor fractures, medial wall fractures, and combined inferior and medial wall fractures. In all patients, bone grafts conformed to the orbital shape and good results were obtained. This simple method uses a reasonable and easy-to-understand approach and is useful in the treatment of bone defects in orbital blowout fractures when using a hard graft material.