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European Spine Journal

, Volume 17, Issue 8, pp 1049–1056 | Cite as

Biomechanical effect of different lumbar interspinous implants on flexibility and intradiscal pressure

  • Hans-Joachim WilkeEmail author
  • J. Drumm
  • K. Häussler
  • C. Mack
  • W. -I. Steudel
  • A. Kettler
Original Article

Abstract

Interspinous implants are used to treat lumbar spinal stenosis or facet joint arthritis. The aims of implanting interspinous devices are to unload the facet joints, restore foraminal height and provide stability especially in extension but still allow motion. The aim of this in vitro study was to compare four different interspinous implants––Colfex, Wallis, Diam and X-Stop––in terms of their three-dimensional flexibility and the intradiscal pressure. Twenty-four human lumbar spine specimens were divided into four equal groups and tested with pure moments in flexion/extension, lateral bending and axial rotation: (1) intact, (2) defect, (3) after implantation. Range of motion and the intradiscal pressure were determined.In each implant-group the defect caused an increase in range of motion by about 8% in lateral bending to 18% in axial rotation. Implantation had similar effects with all four implants. In extension, Coflex, Wallis, Diam, and X-Stop all overcompensated the instability caused by the defect and allowed about 50% of the range of motion of the intact state. In contrast, in flexion, lateral bending and axial rotation the values of the range of motion stayed about the values of the defect state. Similarly the intradiscal pressure after implantation was similar to that of the intact specimens in flexion, lateral bending and axial rotation but much smaller during extension. All tested interspinous implants had a similar effect on the flexibility: they strongly stabilized and reduced the intradiscal pressure in extension, but had almost no effect in flexion, lateral bending and axial rotation.

Keywords

Lumbar spine Interspinous implant Biomechanics Flexibility Intradiscal pressure 

Notes

Acknowledgments

The authors gratefully acknowledge Paradigm Spine for financial support.

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Hans-Joachim Wilke
    • 1
    Email author
  • J. Drumm
    • 2
  • K. Häussler
    • 1
  • C. Mack
    • 1
  • W. -I. Steudel
    • 2
  • A. Kettler
    • 1
  1. 1.Institute of Orthopaedic Research and Biomechanics (Director: L. Claes)University of UlmUlmGermany
  2. 2.Department of NeurosurgerySaarland University HospitalHomburgGermany

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