Bone conduction threshold improvement after otosclerosis surgery.

Abstract

Objective: To analyze the characteristics of bone conduction (BC) threshold changes after stapedotomy in patients with otosclerosis, and to explore the clinical significance and implications for the evaluation of surgical outcomes.

Methods: It is a retrospective, single-center study. A total of 97 ears from patients with otosclerosis who underwent endoscopic stapedotomy (footplate fenestration with titanium piston implantation) between November 2015 and February 2025 were included. Pure tone audiometry (PTA) was performed preoperatively, and at 1 month and 6 months postoperatively. Air conduction (AC) thresholds were tested at 125-8000 Hz, and bone conduction (BC) thresholds at 250-4000 Hz. Pre- and postoperative changes in BC thresholds, AC thresholds, and air-bone gap (ABG) were documented, and the results were compared with findings from other studies.

Results: The average postoperative BC threshold across 250-4000 Hz showed significant improvement, with a mean gain of 7.5 dB (Z = -6.343, p<0.001). At individual frequencies, improvements were significant at 250, 500,1000, 2000 Hz, with the most notable gain at 250 Hz (10 dB), followed by 500 Hz, 1000 Hz, and 2000 Hz (5 dB gain each) (all p<0.001). No statistically significant improvement of BC threshold was observed at 4000 Hz (Z = -0.368, p = 0.713). AC thresholds also showed significant improvements across all tested frequencies (125-4000 Hz) (all p<0.001), with a mean gain of 19 dB; the greatest improvement was observed at 1000 Hz (30 dB). Although the average ABG narrowed by 13 dB, the degree of closure underestimates the actual hearing improvement, as it fails to account for concurrent BC enhancement. Compared with those of other studies, the study cohort demonstrated more pronounced BC improvements.

Conclusion: Stapedotomy not only effectively restores AC hearing but also significantly improves BC thresholds. This improvement in BC thresholds may be attributed to the restoration of bone conduction mechanisms following stapedotomy. Traditional evaluation methods for surgical outcomes that rely solely on ABG closure tend to underestimate overall surgical efficacy. For clinical implementation, we suggest a multidimensional framework can be applied by simultaneously evaluating postoperative air conduction gain, bone conduction gain, and air‑bone gap closure at each frequency, rather than relying on ABG closure alone.