[The application of nasal mucosal flaps in frontal drill out procedures]

Objective: To summarize the follow-up outcomes of frontal drill out procedures (draf Ⅱb, extended draf Ⅱb and draf Ⅲ) using mucosal flaps, and discuss the surgical indications of different mucosal flaps and their potential benefits to the opening of the frontal neo-ostium. Methods: A total of 48 patients with chronic rhinosinusitis or frontal mucoceles treated by draf Ⅱb, extended draf Ⅱb and draf Ⅲ between 2013 and 2019 in Beijing TongRen Hospital were enrolled in this study. Twenty-four patients who were treated with mucosal flaps were considered as mucosal flap group (including 19 males and 5 females, aging from 19 to 71 years), and the other 24 patients who didn't have neo-ostium reconstruction were considered as control group (including 18 males and 6 females, aging from 21 to 63 years). The frontal neo-ostium crosssectional area was measured with osiriX^® 7 days and 1 year postoperatively. Lund-Kennedy score (LKS) was also completed to analyze the difference of therapeutic effect between mucosal flap group and control group. SPSS 23.0 software was used for statistical analysis. Results: The postoperative follow-up time was 18 to 102 months. The postoperative epithelialization time in the mucosal flap group and the control group was (2.5±0.9) months and (3.0±0.7) months (Mean±SD), respectively, with statistically significant (t=1.97, P=0.024). At the end of follow-up, 23 cases (95.8%) had well opened frontal neo-ostium, 1 case (4.2%) was re-stenosed, and there was no revision surgery in the mucosal flap group. In the control group, 16 cases (66.7%) had well opened frontal neo-ostium, 8 cases (33.3%) were re-stenosed, 4 cases (16.7%) had revision surgery. The mucosal flap group had much fewer stenosis cases than control group (χ=4.92, P=0.027). The neo-ostium area in the mucosal flap group and the control group was reduced by (0.87±0.58) cm² and (1.54±1.15) cm² 1 year after operation respectively, with statistically significant (t=1.72, P=0.046). There was no case of frontal sinus atresia and no surgical complication in both groups. The two-factor repeated measurement analysis of variance after surgery showed that the average LKS of the mucosal flap group was 0.78 points lower than that of the control group. In other words, the influence of grafting technique on LKS was statistically significant (F=5.33, P=0.035). Conclusions: The application of mucosal flaps to cover the denuded bone during frontal drill out procedures can prohibit mucosal scar and new bone formation, and significantly reduce the stenosis rate of frontal neo-ostium.