New total ossicular replacement prostheses with a resilient joint: experimental data from XXXX temporal bones.

@entity702 @entity1 @entity1346
HYPOTHESIS: New flexible total ossicular prostheses with an integrated microjoint can compensate for large static displacements in the reconstructed ossicular chain. When properly designed, they can mimic the function of the joints of the intact chain and ensure good vibration transfer in both straight and bent conditions. BACKGROUND: Prosthesis dislocations and extrusions are frequently observed after middle ear surgery. They are mainly related to the altered distance between the coupling points because of large static eardrum displacements. METHODS: The new prostheses consist of 2 @entity702 shafts, which are incorporated into a @entity1346 body. The sound transfer function and stapes footplate displacement at static loads were evaluated in @entity1 temporal bones after ossicular reconstruction using prostheses with 2 different @entity1346 with different hardness values. The stiffness and bending characteristics of the prostheses were investigated with a quasi-static load. RESULTS: The sound transfer properties of the middle ears with the prostheses inserted under uncompressed conditions were comparable with those of ears with intact ossicular chains. The implant with the soft @entity1346 had improved acoustic transfer characteristics over the implant with the hard @entity1346 in a compressed state. In the quasi-static experiments, the minimum medial footplate displacement was found with the same implant. The bending characteristics depended on the @entity1346 stiffness and correlated closely with the point and angle of the load incidence. CONCLUSION: The @entity702 prostheses with a resilient joint that were investigated in this study had good sound transfer characteristics under optimal conditions as well as in a compressed state. As a result of joint bending, the implants compensate for the small changes in length of the ossicular chain that occur under varying middle ear pressure. The implants require a stable support at the stapes footplate to function properly.
