Comparison of tissues for tympanoplasty

Introduction:

Usually the eardrum is reconstructed with autologous fascia, cartilage or perichondrium. These human tissues vary interpersonally in their acousto-mechanical and structural properties. The majority of eardrum defects can be sufficiently closed, but often an air-bone gap (ABG) remains or the perforation reappears. With artificial replacement materials, it is expected that eardrum reconstructions can be performed with consistently good and reproducible results.

Method:

The vibration behaviour of artificial membranes was investigated in comparison to human eardrums and L-PRF (Leucocyte – and Platelet-rich Fibrin). Static pressure was applied and the displacement measured. Vibration modes were measured with a sound excitation of approx. 90 dB SPL. The dynamic measurements were superimposed with the static pressure load in order to simulate pathological boundary conditions.

Results:

In comparison to the normal eardrum L-PRF shows a lower, artificial membranes a higher stiffness. In contrast to cartilage, all other membranes exhibit nonlinear stiffness characteristics similar to those of the eardrum. The first resonance frequency is higher for artificial materials and lower for L-PRF, compared to the human eardrum. When pressure is applied to the eardrum, the low frequencies are reduced and the resonance frequency shifts to higher frequencies.

Conclusion:

The vibrational properties of the membranes are comparable to those of the eardrum. Adjustments are necessary to optimally simulate the drumhead properties. In further investigations, functional influences on the adaptation of the membrane structure and interactions of the artificial membranes with the surrounding tissue are to be investigated in order to estimate the long-term success of the treatment.

Publication History

Publication Date:
23 April 2019 (online)