Cervical disc prostheses need a variable center of rotation for flexion / extension below disc level, plus a separate COR for lateral bending above disc level to more closely replicate in-vivo motion: MRI-based biomechanical in-vivo study

Manfred Muhlbauer*, Ernst Tomasch, Wolfgang Sinz, Siegfried Trattnig, Hermann Steffan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background
Cervical disc prostheses are used to preserve motion after discectomy, but they should also provide a near-physiological qualitative motion pattern. Nevertheless, they come in many completely different biomechanical concepts. This caused us to perform an in-vivo MR-based biomechanical study to further investigate cervical spine motion with the aim to gain new information for improving the design of future cervical arthroplasty devices.
Methods
Fifteen healthy volunteers underwent MRI-investigation (in order to avoid radiation exposure) of their cervical spines from C3 to C7; for each segment centers of rotation (COR) for flexion / extension were determined from 5 different positions, and CORs for lateral bending from 3 different positions. The motion path of the COR is then described and illustrated in relation to the respective COR for maximum flexion / extension or lateral bending, respectively, and the findings are translated into implications for a better biomechanical prosthesis-design.
Results
The COR for flexion / extension does not remain constant during motion. The CORs for the respective motion intervals were always found at different positions than the COR for maximum flexion /extension showing that the COR moves both along the x- and the y-axis throughout flexion / extension. For lateral bending a completely independent COR was found above disc-level.
Conclusion
Flexion / extension is not a simple circular motion. Disc prostheses need a variable COR for flexion / extension below disc level with the capability to move both along the x- and the y-axis during motion, plus a second completely independent COR for lateral bending above disc level to closely replicate in-vivo motion. These findings are important for improving the biomechanical design of such devices in the future.

Original languageEnglish
Article number227
Pages (from-to)1-14
JournalBMC Musculoskeletal Disorders
Volume23
Issue number1
DOIs
Publication statusPublished - 2022

Keywords

  • Cervical arthroplasty
  • Cervical disc prostheses
  • Cervical spine biomechanics
  • In-vivo kinematic study

ASJC Scopus subject areas

  • Rheumatology
  • Orthopedics and Sports Medicine

Fields of Expertise

  • Mobility & Production

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)

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