Biomechanics of the C5-C6 spinal unit before and after placement of a disc prosthesis

F. Galbusera, A. Fantigrossi, M. T. Raimondi, R. Assietti, M. Sassi, M. Fornari

Research output: Contribution to journalArticlepeer-review


The study consists of a biomechanical comparison between the intact C5-C6 spinal segment and the same segment implanted with the BryanTM artificial disc prosthesis (Medtronic Ltd., Memphis, TN, USA), by the use of the finite element (FE) method. Our target is the prediction of the influence of prosthesis placement on the resulting mechanics of the C5-C6 spine unit. A FE model of the intact C5-C6 segment was built, employing realistic models of the vertebrae, disc and ligaments. Simulations were conducted imposing a compression preload combined to a flexion/extension moment, a pure lateral bending moment and a pure torsion moment, and the calculated results were compared to data from literature. The model was then modified to include the BryanTM cervical disc prosthesis, and the simulations were repeated. The location of the instantaneous center of rotation (ICR) of C5 with respect to C6 throughout flexion/extension was calculated in both models. In general, the moment-rotation curves obtained from the disc prosthesis-implanted model were comparable to the curves obtained from the intact model, except for a slightly greater stiffness induced by the artificial disc. The position of the calculated ICRs was rather stable throughout flexion-extension and was generally confined to a small area, qualitatively matching the corresponding physiological region, in both models. These results imply that the BryanTM disc prosthesis allows to correctly reproduce a physiological flexion/extension at the implanted level. The results of this study have quantified aspects that may assist in optimizing cervical disc replacement primarily from a biomechanical point of view.

Original languageEnglish
Pages (from-to)253-261
Number of pages9
JournalBiomechanics and Modeling in Mechanobiology
Issue number4
Publication statusPublished - Nov 2006

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Computer Science(all)
  • Physics and Astronomy (miscellaneous)


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