The Laryngoscope V C 2017 The American Laryngological, Rhinological and Otological Society, Inc. Does the Diameter of the Stapes Prosthesis Really Matter? A Prospective Clinical Study Daniele Bernardeschi, MD, PhD ; Daniele De Seta, MD, PhD; Giuseppina Canu, MD; Francesca Yoshie Russo, MD; Evelyne Ferrary, MD, PhD; Ghizlene Lahlou, MD; Olivier Sterkers, MD, PhD Objectives/Hypothesis: To evaluate the influence of the diameter of stapes prosthesis on functional outcomes in stapes surgery. Study Design: Prospective cohort study. Methods: Fifty consecutive small fenestra stapedotomies performed using a 0.4-mm-diameter prosthesis were compared with 50 consecutive small fenestra stapedotomies carried out using a 0.6-mm-diameter piston. Audiological assessment following the recommendations of the Committee on Hearing and Equilibrium was performed 1 month after surgery. Postoperative complications between the two groups were noted. Results: There were no statistically significant differences in demographic data between the two groups, and no differ- ences in preoperative bone-conduction (BC) or air-conduction (AC) hearing thresholds for all frequencies (analysis of variance [ANOVA] and v 2 tests). No differences were found in the mean preoperative BC and AC pure-tone average and air-bone gap (ABG). In the postoperative evaluation, a statistically significant difference was found for the mean AC gain (20 6 8.7 vs. 24 6 11.5, P 5 .042, ANOVA) as well as for the postoperative AC threshold at 0.125 and 0.25 kHz and the postoperative BC threshold at 0.25 kHz (P < .01, ANOVA). A postoperative ABG 10 dB was obtained in 90% and 94% of patients in the 0.4-mm- and 0.6-mm-diameter piston groups, respectively (difference not significant, v 2 test). No postoperative dead ear and/or sensorineural hearing loss was noted in either group. Conclusions: The 0.6-mm piston allowed a statistically significant higher AC gain compared with the 0.4-mm diameter piston. A larger diameter piston may be preferable if there are no anatomical or technical reasons that would favor a smaller prosthesis. Key Words: Otosclerosis, piston, middle ear, laser, nitinol. Level of Evidence: 2b Laryngoscope, 00:000–000, 2017 INTRODUCTION Otosclerosis is an osteodystrophic disease of the otic capsule 1 responsible for hearing loss when it causes fixa- tion of the stapes and/or when it involves the cochlear endosteum. When hearing loss is considered to be annoy- ing by the patient, surgery could be an option. Since the seminal work of Shea, 2 who first described the technique of total stapedectomy with interposition of a polyethyl- ene implant in fibrous tissue, many modifications of the original technique have been described in the literature; small fenestra stapedotomy 3,4 has gained popularity over the years together with the use of a laser. 5,6 Moreover, many different pistons have been developed to improve the functional results and to reduce complications. The diameter of the piston is one of the variables thought to affect the functional results. Mathematical models on mechanical and acoustic analysis of middle ear reconstruction 7 (and on the biomechanics of stape- dotomy 8 ) seemed to indicate that a larger diameter pis- ton is associated with better sound transmission to the inner ear. A recent experimental study 9 on temporal bone demonstrated that a larger diameter prosthesis increased the round window velocities, thus slightly improving hearing results. In a clinical scenario, the influence of piston diame- ter is more difficult to demonstrate, because many fac- tors play a role in functional outcome including surgical technique, 10 experience of the surgeon, 11 piston used, 12 length of the piston, 13 and the efficacy of crimping for a manually crimped prosthesis. 14 The aim of this prospective clinical study was to evaluate the functional results of stapes surgery per- formed in our institution by the two most experienced stapes surgeons with the same piston but with two different piston diameters. From the Department of Otolaryngology, Unit of Otology, Auditory implants and Skull base surgery, Public Assistance-Paris Hospital, Piti e- Salp^ etrie `re Group Hospital, Paris, France; and Minimally Invasive Sur- gical Robotic Rehabilitation of Hearing, French Institute of Health and Medical Research, Mixed Unit of Research-S 1159, Paris, France. Editor’s Note: This Manuscript was accepted for publication October 27, 2017. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Daniele Bernardeschi, MD, Otology, Auditory Implants, and Skull Base Surgery Department, Piti e- Salp^ etrie `re Hospital, 50/52 Boulevard Vincent Auriol, 75013 Paris, France. E-mail: daniele.bernardeschi@aphp.fr DOI: 10.1002/lary.27021 Laryngoscope 00: Month 2017 Bernardeschi et al.: Diameter of the Stapes Prosthesis 1