Fig. 1.

a CT cisternography image showing the defect in the inner table of left frontal sinus, b Frontal sinus delineation using navigation and use of needles to mark the margins, c Navigation image showing left frontal sinus in coronal, axial and sagittal planes, d osteoplastic flap raised (yellow arrow), e Image showing autologous cartilage used as graft for repairing defect in the posterior wall of left frontal sinus, f postoperative image showing the healed brow incision, g Post-operative X-ray of the paranasal sinuses in Caldwell luc view showing obliterated left frontal sinus using bioglass