Objectives/HypothesisThe performance of an ossicular replacement prosthesis (ORP) is influenced by its alignment and appropriate tension between the tympanic membrane and the stapes footplate. A novel ORP with a flexible element that potentially allows for length adjustment in situ is presented and tested for acoustic performance. Study DesignLaser Doppler vibrometry in fresh human cadaveric temporal bones was used to test the acoustic performance of the adjustable ORP relative to standard prostheses used for ossiculoplasty. MethodsThe three-dimensional (3D) velocity of the stapes posterior crus was measured in the 0.2- to 20-kHz range using a Polytec CLV-3D laser Doppler vibrometer. The middle ear cavity was accessed through a facial recess approach. After measuring the normal response, the incus was removed and stapes velocity was measured in the disarticulated case, then after insertion of the new prosthesis, a conventional prosthesis (Kurz BELL Dusseldorf type), and a sculpted autologous incus prosthesis in each temporal bone. The 3D stapes velocity transfer function (SVTF) was calculated for each case and compared. ResultsThe novel ORP design restored stapes velocity to within 6 dB (on average) of the intact response. No significant differences in 3D-SVTF were found between the new, conventional, or autologous ORPs. ConclusionsThe inclusion of an in situ adjustable element into the ORP design did not adversely affect its acoustic performance. The adjustable element may increase the ease of achieving optimal ORP placement, especially through a facial recess approach. Level of EvidenceNA Laryngoscope, 126:2559-2564, 2016