[Stapes surgery for otosclerosis using a new titanium prosthesis with a superelastic nitinol clip: First experiences]

Coupling of the prosthesis to the long process of the incus is a critical step in stapes surgery. We report first experiences with the NiTiFLEX® stapes prosthesis, a further development of the Soft CliP® stapes prosthesis (Kurz, Dusslingen, Germany). Instead of pure titanium, the CliP® now consists of nitinol, a superelastic nickel-titanium alloy. This further reduces the pressure exerted on the long process of the incus, aiming to improve coupling and minimize the risk of incus luxation.

In a monocentric, retrospective cohort study, we evaluated air-bone gap reduction (4PTA0.5-4 kHz), understanding of monosyllables at 65 and 80 dB SPL stimulation levels, and adverse effects, such as changes in bone conduction (4PTA0.5-4 kHz). During a 12-month period (May 2014 to April 2015), stapes surgery was performed in 21 otosclerosis patients using the NiTiFLEX® prosthesis. The footplate was perforated using a CO2 laser (scanning mode; 0.7 mm; 20-21 W) in almost all cases. The diameter of the titan piston was 0.4 mm. Immersion at an angle of almost 90° thus results in a gap between the footplate perforation and the piston of 0.15 mm. Positioning onto the long incus process was performed with a 90°microhook (0.6 mm).

In all cases the NiTiFLEX® stapes prosthesis was inserted without complications. The mean bone conduction threshold did not change significantly postoperatively and the mean air-bone gap (4PTA0.5-4 kHz) improved on average from 29.0 to 9.5 dB HL. Handling of the prosthesis was rated as very good.

The limited experience of this study suggests that the NiTiFLEX® stapes prosthesis is a successful further development of the Soft CliP® technique with very good intraoperative handling qualities. While long-term results from larger studies are needed, this case series demonstrates that the hearing outcome is comparable to other prostheses.