The Relationship between Stapes Prosthesis Length and Rate of Stapedectomy Success.

Objectives: To identify whether measurement of the prosthesis length is mandatory in patients requiring otosclerosis surgeries and to assess their postoperative audiometric outcomes. In addition, evaluation of prosthesis length used in revision compared to primary stapedectomy was carried out.

Study Design: Case series with chart review.

Methods: Chart review of 393 patients undergoing primary (321) versus revision stapedectomy (72) was performed in a tertiary referral center. The indication for surgery was the presence or persistence/recurrence of an air-bone gap (ABG) greater than 20 dB. Air and bone conduction thresholds (ACT and BCT, respectively), ABG as well as pure tone averages (PTAs) were determined for all patients, and the results were compared preoperatively and postoperatively.

Results: Prosthesis length used ranged from 3.0 to 6.0 mm without differences between primary and revision groups. Of the revision surgeries, 62.5% were stapedectomies versus stapedotomies (P < 0.001). Patients showed significant decrease in speech discrimination score, with increased air and bone conduction thresholds as well as mean ABG and PTA before the revision surgeries as a first procedure failure. Prosthesis length changes occurred in 73.5% of the cases, with an average absolute change of 0.55 mm. Prosthesis length did not affect postoperative audiometric results between primary and revision groups, in all surgeries combined. When grouping stapes surgery into accurately versus inaccurately measured incus-footplate distance, significant differences were observed in prosthesis length employed (P < 0.01). Hearing outcomes were also better in the group in which an accurately measured prosthesis was chosen, as opposed to "standard-length" prosthesis.

Conclusions: This study corroborates postoperative success rates of revision surgeries, which show smaller improvements in hearing compared to a primary intervention. Accurate intra-operative measurement of prosthesis length was correlated with better audiometric results postoperatively.