Year: 2026 | Month: July-September | Volume: 11 | Issue: 3 | Pages: 56-63
DOI: https://doi.org/10.52403/ijshr.20260307
Audiological Outcome in Underlay Versus Interlay Type 1 Tympanoplasty
Mohd. Farook1, Seema Monga2, Ratna Priya3, Taniya Maity4
1Junior Resident, 2HOD and Professor, 3Assistant Professor, 4Senior Resident,
Department of E.N.T., HAH Centenary Hospital and Hamdard Institute of Medical Sciences and Research,
New Delhi, India
Corresponding Author: Dr. Ratna Priya
ABSTRACT
Background and objective: Type I Chronic Otitis Media (COM) with permanent tympanic membrane perforation is a major cause of conductive hearing loss, particularly in low- and middle-income countries. This prospective comparative study evaluated the anatomical (graft success) and audiological (air-bone gap closure) outcomes of underlay versus interlay techniques using temporalis fascia graft.
Methods: This prospective comparative study was conducted between January 2023 and January 2025 at a tertiary-care hospital in Northern India. Forty-six patients with mucosal COM and large central or subtotal tympanic membrane perforations were randomly allocated to undergo either interlay (n=23) or underlay (n=23) type I tympanoplasty. Preoperative assessment included otoscopic examination and pure-tone audiometry. Patients were followed for three months to evaluate graft integrity and postoperative hearing. The primary outcome was improvement in the air–bone gap (ABG), while graft uptake served as the secondary outcome. Statistical analysis was performed using appropriate parametric and non-parametric tests, with a significance level of p<0.05.
Results: Successful graft uptake was achieved in 91.3% of patients in the interlay group and 100% in the underlay group, without a statistically significant difference (p=0.473). Both techniques resulted in significant postoperative hearing improvement. Mean ABG improvement was significantly greater in the underlay group than in the interlay group (24.7±4.7 dB vs. 11.3±8.7 dB; p<0.001). No postoperative infections or major complications were observed in either group.
Conclusion: Both underlay and interlay type I tympanoplasty are safe and effective techniques for repairing tympanic membrane perforations in chronic otitis media. Although both achieved excellent anatomical outcomes, the underlay technique produced significantly greater audiological improvement. Larger randomized studies with longer follow-up are needed to confirm these findings and evaluate long-term functional outcomes.
Keywords: Tympanoplasty; Underlay; Interlay; Chronic Otitis Media; Air-Bone Gap; Temporalis Fascia; Graft Success