Mobilization and luxation of the stapes during robot-assisted otosclerosis surgery: force and distance analysis.

PURPOSE: To evaluate the forces and distances applied during robot-assisted stapes mobilization and stapedovestibular luxation in temporal bone specimens.

METHODS

The inner ear of 12 cadaveric human temporal bones was filled with methylene blue dye via the superior semicircular canal and internal auditory canal under a controlled static pressure of 10 cm H₂O. The stapes footplate was fixed with hydroxyapatite cement. Stapes robot-assisted mobilization was performed until the stapes could be freely mobilized without fluid leakage at the annular ligament, followed by stapedovestibular luxation until fluid leakage occurred. A six-axis force sensor (Nano17, ATI) recorded peak forces (N) during each manipulation. Distance (mm) of the tool against the long process of the incus was also measured.

RESULTS

Stapes mobilization and stapedovestibular luxation required maximal forces of 1.4 ± 0.18 N and 2.6 ± 0.31 N (p = 0.0054, Mann-Whitney test), respectively. Distance was 1.5 ± 0.24 mm and 1.9 ± 0.13 mm for stapes mobilization and stapedovestibular luxation, respectively (NS, Mann-Whitney test). Incus luxation happened in four manipulations at a force of 2.0 ± 0.61 N and distance of 2.5 ± 0.59 mm.

CONCLUSION

Under the experimental conditions of this study, successful stapes mobilization appeared associated with manipulation within the stapes plane and forces and distances generally below approximately 1.5 N and 1.5 mm, respectively, requiring further clinical validation.