Comparison of endoscopic underlay and over-under tympanoplasty techniques for type I tympanoplasty

Objective: To compare the indications and efficacy of endoscopic over-under tympanoplasty versus endoscopic underlay tympanoplasty. Methods: Retrospective cohort study of patients undergoing type I endoscopic tympanoplasty via either an underlay or over-under technique by a single surgeon from 2017 to 2021. Patients were excluded if they had a concurrent mastoidectomy, ossiculoplasty, or advanced cholesteatoma defined by involvement of multiple subsites. Patient demographics, perforation size and location, middle ear status, preoperative and postoperative audiograms, and perforation closure were reviewed. Middle ear status was represented using the Ossiculoplasty Outcome Parameter Score (OOPS). The primary outcome was perforation closure at most recent follow-up and secondary outcomes were change in postoperative pure-tone average (PTA) and air-bone gap (ABG). Results: Of 48 patients, 27 underwent endoscopic underlay tympanoplasty and 21 underwent endoscopic over-under tympanoplasty. Tragal cartilage-perichondrium graft was used in 90% of procedures. Distribution of OOPS scores was not significantly different between groups. Over- under technique addressed significantly larger perforations (mean size of 54% vs. 31%, p <.001) and a higher rate of anterior extension (95% vs. 22%, p <.001) than underlay technique. Perforation closure rate was not different between groups (95% vs. 96%). Patients experienced significant improvement in PTA and ABG in both groups. Conclusion: The endoscopic over-under tympanoplasty is comparable to endoscopic underlay tympanoplasty in terms of graft take and audiologic improvement. The over-under technique is effective for repairing larger perforations or those with anterior extension. Level of evidence: IV.