Modified Lothrop Procedure (Draf III Procedure)

The modified Lothrop procedure, or Draf III procedure, may also be referred to as median drainage. This procedure, in its present form, was first described in the mid-1990s and has been gaining popularity among rhinologists. Indications include the most severe forms of chronic frontal sinusitis where osteoplastic flap with obliteration is the only alternative. This procedure involves removal of the inferior portion of the interfrontal septum, the superior part of the nasal septum, and the frontal sinus floor to the orbit laterally. The lamina papyracea and posterior walls of the frontal sinus remain intact. Postoperatively, a wide opening into both frontal sinuses can be seen. The surgical defect in the superior nasal septum should not be mistaken for an unintended postoperative septal perforation.

Schematic of Draf III (modified Lothrop) procedure shows more extensive dissection including removal of the superior nasal septum, anterior ethmoid cells, intersinus septum, and floor of both frontal sinuses. (Adapted from Draf, ref. 1)
Coronal CT in a patient following modified Lothrop (Draf III) procedure. The frontal sinuses are well-aerated and an extensive drainage pathway has been created. The surgical defect in the nasal septum (arrow) should not be misinterpreted as an unintended septal perforation.
Endoscopic view (45 degree endoscope) of a modified Lothrop procedure. The intersinus septum (arrow) has been partially removed and both frontal sinuses (f) are visualized through the superior septal resection. The image on the right demonstrates the powered drill adapted for endoscopic use to remove the hard bone of the anterior frontal sinus.
Series of images in patient who was initially treated for bilateral frontal sinus disease with bilateral Draf I procedures, but had persistent disease within the left frontal sinus likely secondary to adhesions within the frontal recess (asterisk) (Fig. A). A Draf III procedure was performed (Fig. B), and a follow-up CT (Fig. C) showed clearing of the left frontal sinus (f).
Coronal CT images in a patient after modified Lothrop (Draf III) procedure with persistent frontal pressure and recurrent infections. There is persistent opacification of the frontal sinuses and the surgical defects in the inferior frontal sinuses are occluded. This is a radiographic endoscopic modified Lothrop (Draf III) failure.