gms | German Medical Science

61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

Avoiding the foraminal stenosis – the role of core bearing geometry in cervical TDR: CAD simulation analysis

Meeting Abstract

  • Richard Bostelmann - Neurochirurgische Klinik der Heinrich Heine Universität, Düsseldorf, Germany
  • Mario Leimert - Klinik für Neurochirurgie am Universitätsklinikum Carl Gustav Carus, Dresden, Germany
  • Jan Frederick Cornelius - Neurochirurgische Klinik der Heinrich Heine Universität, Düsseldorf, Germany
  • Hans Jakob Steiger - Neurochirurgische Klinik der Heinrich Heine Universität, Düsseldorf, Germany

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocP1791

doi: 10.3205/10dgnc262, urn:nbn:de:0183-10dgnc2626

Published: September 16, 2010

© 2010 Bostelmann et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: There is a need for accommodation of the foraminae during physiological movement of the cervical spinal motion segment. If their volume is decreased too much, there will be irritation of the nerve root. By implanting artificial disc replacements the segmental motion could be preserved. Questionable is still the quality of motion pattern in comparison to intervertebral space’s proper natural kinematic, especially compensatory displacement. If motion is denaturated foraminae may lose their continuous instantaneous volume adaption. Logically consistent this will lead to impingement of the nerve root in various degrees. The goal will be to providing a cervical disc prosthesis which would emulate the natural intervertebral motion, maintain foraminal volume and avoid transforaminal undesired shearing forces.

Methods: Elevation in flexion, extension and lateral bending axes versus angular displacement was evaluated in a 3D CAD simulated model of a special formed cervical TDR (Cerkinetik™). The prosthesis was virtually implanted within C5-6 solid cervical 3D simulated cervical spine. Elevations were recorded. Volume, dimensions and shapes of the foraminae were evaluated and graphically analyzed.

Results: Mean prosthesis simulated elevation in all 3 axes is ~0.5 mm. See graphic foraminae analysis.

Conclusions: Natural foraminae volume was preserved assumable due to TDR geometry and the consequent induced characteristic motional pattern. Unnatural shearing forces that might distort the foraminae and impinge nerve roots are avoided. The motional versatility conferred by specific geometry of the examined prosthesis as described and demonstrated, enables the facet joints to assume their natural position adjustment as an integral component of the treated level milieu.