FEA Simulation of Crimping Pressure Distribution in Titanium and Teflon Stapedotomy Prostheses

Area of Science:

• Biomedical Engineering
• Otolaryngology
• Materials Science

Background:

• Stapedotomy surgery aims to restore hearing in otosclerosis patients by using a prosthesis to reconnect the incus to the oval window.
• Complications like incudal necrosis can arise from excessive stress on the incus bone due to the prosthesis fixation.

Purpose of the Study:

• To investigate the biomechanical effects of different prosthesis materials (titanium vs. PTFE), crimping forces, and loop geometries on the incus.
• To identify optimal parameters for prosthesis fixation that minimize stress and prevent incudal necrosis.

Main Methods:

• Finite element analysis (FEA) was employed to simulate interface pressures and von Mises stresses.
• Analyses were conducted on titanium prostheses with varying band widths (0.2-0.5 mm) and crimping forces (300-500 mN).
• FEA was also performed on PTFE prostheses with different outer diameters (1.2-1.8 mm).

Main Results:

• PTFE prostheses generated significantly lower interface pressures and stresses compared to titanium.
• PTFE prostheses exhibited stresses well below the critical threshold for incudal bone.
• Titanium prostheses showed high stress levels, especially at higher crimping forces (≥400 mN) and wider band widths (>0.3 mm), exceeding bone strength thresholds and risking incudal necrosis.

Conclusions:

• PTFE prostheses offer a safer alternative to titanium due to lower mechanical stress on the incus.
• Careful control of crimping force and selection of prosthesis material and geometry are essential for secure stapedotomy fixation while preserving incus integrity.