How Stapes Ankylosis and Fracture Affect Middle Ear Dynamics: A Numerical Study

Area of Science:

• Biomechanics
• Medical Imaging
• Computational Biology

Background:

• Numerical models of the human middle ear are crucial for understanding auditory function.
• Stapedial disorders, unlike other middle ear pathologies, have been less explored computationally.
• Accurate modeling is essential for diagnosing and treating hearing loss.

Purpose of the Study:

• To investigate the effects of stapes fracture and ankylosis on middle ear sound transmission.
• To analyze stapes dynamics, including total displacement and principal strain, under pathological conditions.
• To quantify the impact of specific stapedial disorders like stapedial tendon ossification and augmented pyramidal eminence.

Main Methods:

• Development and validation of a 3D finite element model of the human middle ear.
• Modification of the model to simulate stapes fracture and various forms of stapes ankylosis.
• Establishment of a metric to evaluate sound transmission reduction caused by these disorders.

Main Results:

• Stapes ankylosis primarily affects low-frequency sound transmission, while stapes fractures impact high frequencies.
• Augmented pyramidal eminence alone does not impede stapes movement unless accompanied by stapedial tendon ossification.
• Fracture location (anterior/posterior crus) and proximity to the footplate significantly influence sound transmission reduction.

Conclusions:

• The study provides quantitative insights into how stapes fractures and ankylosis alter middle ear mechanics.
• Finite element modeling effectively differentiates the effects of various stapedial disorders on sound transmission.
• Findings can inform clinical understanding and treatment strategies for hearing impairments related to stapes pathologies.