Comparison of Audiometric and Functional Outcomes Between the Standard and Modified 360 Nitinol Shape Memory Stapes Prostheses.

OBJECTIVE: To compare audiometric and functional outcomes between two designs of heat-activated self-crimping stapes prostheses-a modified shape memory circumferential nitinol-Teflon piston versus its predecessor-in patients with otosclerosis. STUDY DESIGN: A retrospective analysis of preoperative and postoperative hearing thresholds. SETTING: Tertiary referral center and teaching hospital. PATIENTS: One hundred sixty-three consecutive procedures of primary stapes surgery for clinically proven otosclerosis in 108 women and 55 men with an average age of 46 years. INTERVENTION: Stapedotomy and insertion of either a standard or a circumferential stapes prosthesis. MAIN OUTCOME MEASURES: Four-frequency pure-tone average preoperative and postoperative air-bone thresholds were recorded. A secondary outcome measure was stability of the implant, as measured by failure rates. RESULTS: Success of closure of the air-bone gap to within 10 dB was achieved in 97% and comparable in both groups (original prosthesis, 23.6; standard deviation, 7.3, with the average reduction seen in the circumferential prosthesis group being 22.6, standard deviation, 5.6). All the differences were not statistically significant using two-way analysis of variance. Failure rate for the original piston was 6%, with no failures seen with the circumferential piston. CONCLUSION: Both prostheses showed comparable postoperative hearing outcomes, with the circumferential prosthesis being found to be more stable.