Archives of Orthopaedic and Trauma Surgery

, Volume 130, Issue 2, pp 285–292

How does spinal canal decompression and dorsal stabilization affect segmental mobility? A biomechanical study

  • Karl-Stefan Delank
  • Erol Gercek
  • Sebastian Kuhn
  • Frank Hartmann
  • H. Hely
  • Marc Röllinghoff
  • M. A. Rothschild
  • H. Stützer
  • Rolf Sobottke
  • Peer Eysel
Basic Science

DOI: 10.1007/s00402-009-1002-x

Cite this article as:
Delank, KS., Gercek, E., Kuhn, S. et al. Arch Orthop Trauma Surg (2010) 130: 285. doi:10.1007/s00402-009-1002-x

Abstract

Introduction

When decompression of the lumbar spinal canal is performed, segmental stability might be affected. Exactly which anatomical structures can thereby be resected without interfering with stability, and when, respectively how, additional stabilization is essential, has not been adequately investigated so far. The present investigation describes kinetic changes in a surgically treated motion segment as well as in its adjacent segments.

Material and methods

Segmental biomechanical examination of nine human lumbar cadaver spines (L1 to L5) was performed without preload in a spine-testing apparatus by means of a precise, ultrasound-guided measuring system. Thus, samples consisting of four free motion segments were made available. Besides measurements in the native (untreated) spine specimen further measurements were done after progressive resection of dorsal elements like lig. flavum, hemilaminectomy, laminectomy and facetectomy. The segment was then stabilised by means of a rigid system (ART®) and by means of a dynamic, transpedicularly fixed system (Dynesys®).

Results

For the analysis, range of motion (ROM) values and separately viewed data of the respective direction of motion were considered in equal measure. A very high reproducibility of the individual measurements could be verified. In the sagittal and frontal plane, flavectomy and hemilaminectomy did not achieve any relevant change in the ROM in both directions. This applies to the segment operated on as well as to the adjacent segments examined. Resection of the facet likewise does not lead to any distinct increase of mobility in the operated segment as far as flexion and right/left bending is concerned. In extension a striking increase in mobility of more than 1° compared to the native value can be perceived in the operated segment. Stabilization with the rigid and dynamic system effect an almost equal reduction of flexion/extension and right/left bending. In the adjacent segments, a slightly higher mobility is to be noted for rigid stabilization than for dynamic stabilisation. A linear regression analysis shows that in flexion/extension monosegmental rigid stabilisation is compensated predominantly in the first cranial adjacent segment. In case of a dynamic stabilisation the compensation is distributed among the first and second cranial, and by 20% in the caudal adjacent segment.

Summary

Monosegmental decompression of the lumbar spinal canal does not essentially destabilise the motion segment during in vitro conditions. Regarding rigid or dynamic stabilisation, the ROM does not differ within the operated segment, but the distribution of the compensatory movement is different.

Keywords

Segmental motion Decompression Dynesys® Lumbar spine Segmental instability 

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Karl-Stefan Delank
    • 1
  • Erol Gercek
    • 2
  • Sebastian Kuhn
    • 2
  • Frank Hartmann
    • 2
  • H. Hely
    • 3
  • Marc Röllinghoff
    • 1
  • M. A. Rothschild
    • 4
  • H. Stützer
    • 5
  • Rolf Sobottke
    • 1
  • Peer Eysel
    • 1
  1. 1.Department of Orthopaedic and Trauma SurgeryCologne UniversityCologneGermany
  2. 2.Department of Orthopaedic and Trauma SurgeryUniversity Hospital of the Johannes Gutenberg-University of MainzMainzGermany
  3. 3.Section Engineering PhysicsUniversity of Applied Science of WiesbadenWiesbadenGermany
  4. 4.Department of Legal MedicineCologne UniversityCologneGermany
  5. 5.Institute of Medical Statistics, Informatics and EpidemiologyCologne UniversityCologneGermany