This is a retrospective case series study. The Draf III procedure exposes excessive bare bone, resulting in frontal ostium restenosis and surgical failure. For tumors originating from frontal sinus, especially inverted papillomas, abrading of bone around frontal ostium often exacerbate the restenosis. This study aims to retrospectly recruit patients with frontal sinus inverted papillomas who received Draf III procedure in our center during 2015-2021 and investigated the efficacy of a novel pedicled nasoseptal flap for endoscopic frontal sinus procedures. Each subject received a CT and magnetic resonance imaging (MRI) scans before operation. The subjects were followed up postoperative for at least 12 months to check the epithelization status and whether the neo-ostium were patent.

The standard Draf III procedure was performed as described by Gross and Wormald using an "outside-in" technique. The cranial portion of the nasal septum was removed, and the frontal process of the maxilla and frontal beak were carefully abraded, resulting in the "frontal T". Distinct to the procedure of Gross and Wormald, the frontal T was then lowered to the first branch of the anterior ethmoidal artery instead of the first olfactory fibre.

Tumors were totally resected under endoscope and lateral pedicled nasoseptal flaps were applied for covering the exposed bone around frontal neo-ostium. The pedicled nasoseptal flaps were applied in the experimental group and no flap was applied in the control group.

The pedicle of the flap was designed to be on the frontal process of the lateral nasal wall. The lateral anterior incision was approximately 1 cm anterior to the maxillary line, with the medial anterior limit in parallel on the septum. The lateral posterior limit was the maxillary line and medial posterior limit parallel to the anterior limit where the first branch of the anterior ethmoidal artery arises on ethmoidal roof. The lower limit of the septal part was at the level of the lower border of the middle turbinate. The flap was carefully elevated from the cartilage and bone, particularly the supra-axillary and olfactory fossa part. The flap was then persevered posteriorly in the nasal floor or maxillary sinus for subsequent use. The contralateral flap was harvested and preserved in a similar manner. Type 1 flaps consisted of mucosa over the lateral nasal wall, and type 2 flaps consisted of the aforementioned mucosa and corresponding septal mucosa.

All patients were followed up for at least 12 months, and the nasal cavity was assessed and cleaned regularly under endoscopy. The neo-ostium section area was compared to that at the end of surgery. Epithelization was identified if the neo-ostium were smooth without edema, discharging or crusting after surgery under endoscope. The time required for epithelialization of each patient was also recorded. Restenosis was defined as >50% reduction in the section area at 12 months postoperatively.

Inclusion Criteria:

1. Adult patients with bilateral frontal inverted papilloma who received a endoscopic endonasal Draf III surgery.
2. Ages range from 18-85 years old.
3. Preoperative CT and MRI scanning show favourable frontal sinus pneumatization.
4. Patients who are willing to following up regularly with good compliance.

Exclusion Criteria:

1. Patients who had undergone prior partial septectomy or septal perforation.
2. Patients who can't finish a regular 1-year follow-up.

Adult patients with bilateral frontal inverted papilloma who received a endoscopic endonasal Draf III surgery between 2015 to 2021 in our center.

We haven't decided yet about the IPD sharing.