Explant analysis of two rhine cervical discs.
Göksu Kandemir, Paul Rushton, Thomas Joyce et al.
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From the abstract
Cervical disc replacement aims to preserve cervical spine motion and reduce the risk of adjacent segment disease. The Rhine cervical disc is a non-articulating, viscoelastic implant designed to replicate the natural biomechanics of the cervical spine. To date, no explant analyses of this device have been published.
Reported results
Both explants were intact, however, notable findings included plastic deformation of the viscoelastic cores, particularly in the upper disc. The direction of shear deformation differed between the explants, anterior in the upper disc and posterior in the lower disc, suggesting asymmetric loading conditions.
Authors' conclusions
These observations highlight deformation of the viscoelastic core in Rhine cervical discs. Whether this finding relates to surgical factors such as implant sizing and positioning, or to implant design itself, improper sizing and malpositioning may contribute to excessive shear forces, core deformation, and poor clinical outcomes. These factors are all important in implant survival and should be carefully considered.