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Experimental Study of Needle Insertion into Gerbil Tympanic Membrane.
Hossein Mohammadi1,2, Arash Ebrahimian1,2, Nima Maftoon3,4
1Department of Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada.
Summary
Understanding tympanic membrane (TM) perforation mechanics is crucial for middle ear surgery. Gerbil TM fracture toughness was determined to be approximately 0.33 kJ/m², independent of needle geometry, offering insights for surgical tool design.
Area of Science:
- Biomechanics
- Otolaryngology
- Materials Science
Background:
- Tympanic membrane (TM) perforation characteristics are vital for middle ear surgical success.
- Procedures like myringotomy and tympanostomy require precise understanding of TM mechanical properties.
Purpose of the Study:
- To analyze gerbil tympanic membrane (TM) perforation mechanics.
- To determine fracture-related mechanical properties relevant to surgical interventions.
Main Methods:
- Experimental force measurement during a 2-cycle needle insertion/extraction process.
- Analysis of fracture energy, friction energy, strain energy, and hysteresis loss.
- Evaluation of needle geometry and insertion velocity effects on perforation.
Main Results:
- TM exhibits viscoelastic behavior, with negligible hysteresis loss compared to fracture and friction energy.
- Puncture force remained stable post-mortem but increased after a week due to drying.
- Needle diameter and insertion velocity significantly influenced perforation forces and crack length.
- Gerbil TM fracture toughness was determined to be approximately 0.33 ± 0.10 kJ/m², independent of needle geometry.
Conclusions:
- Fracture and friction energies are the primary contributors to dissipated energy during TM perforation.
- Tissue drying post-mortem affects TM mechanical properties.
- Needle design and insertion parameters can be optimized based on these findings for improved surgical outcomes.
