Figure 8: Bird’s columella and bended prosthesis. Direct comparison of an ostrich’s middle ear a and b with a bended TORP c and d under conditions of pressure balance a and c or a positive pressure in the auditory canal (negative pressure in the tympanic cavity) b and d. The movement of the prosthesis stem reduces the stress of ring ligament and footplate. When the pressure decreases, the original position is restored in both cases. So the bended prosthesis does not only represent the reconstruction of the sound conduction apparatus, but also to a certain extent the pressure balance of the intact ossicular chain (figures A and B: courtesy of Beleites et al. 2007 [108]).