Three-dimensional alloplastic orbital reconstruction in skull base surgery.

INTRODUCTION The orbit may be directly involved by neoplasms or other destructive processes arising from the orbital contents, the osseous framework or, indirectly, as extensions of extraorbital tumors from the sinuses or cranial vault. In most osseous neoplasms of the orbit, and in tumors with extension into the orbit from surrounding areas, resection of part or all of the orbital walls will be required. If fronto-orbital osteotomies are performed as part of a craniofacial disassembly approach to a skull base tumor, the osteotomized segments are simply replaced at the completion of the procedure with no significant osseous deformity. However, precise restitution of the threedimensional shape and position of the orbital skeleton is vital to decrease the perceived esthetic deformity that will follow significant orbital wall resection. Traditionally, significant osseous orbital defects in craniofacial surgery have been replaced most commonly with calvarial bone grafting using the principles of rigid internal fixation. Resorption or secondary malposition is less often a concern with calvarial bone grafts as compared with other sites (iliac crest, rib, etc.). Although calvarial bone graft reconstruction of significant orbital defects is straightforward in theory, achieving reliably rewarding esthetic and functional results is difficult. This is largely the result of the difficulty in reproducing the delicate threedimensional contour of the native orbit with flat or only slightly curved bone grafts. In addition, orbital reconstruction with bone grafts may be time consuming, as well as having the potential for donor site morbidity. An ideal graft for orbital reconstruction would be biocompatible, be readily available in large quantities, have no donor site morbidity, become integrated over time by bony ingrowth, and allow for the formation of a stable three-dimensional construct. In this article, we outline our approach to this difficult reconstructive problem using titanium mesh impregnated with hydroxyapatite cement.