gms | German Medical Science

65th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

11 - 14 May 2014, Dresden

Article

Send article

Biomechanical testing of circumferential instrumentation after multilevel cervical corpectomy

Meeting Abstract

Search Medline for

  • Sebastian Hartmann - Department of Neurosurgery, Campus Mannheim, University of Heidelberg
  • Aldemar Andres Hegewald - Department of Neurosurgery, Campus Mannheim, University of Heidelberg
  • Alexander Keiler - Department of Trauma Surgery, Campus Mannheim, University of Heidelberg
  • Helga Fritsch - Department of Anatomy, Medical University Innsbruck, Austria
  • Claudius Thomé - Department of Neurosurgery, Campus Mannheim, University of Heidelberg
  • Werner Schmölz - Department of Trauma Surgery, Campus Mannheim, University of Heidelberg

Deutsche Gesellschaft für Neurochirurgie. 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Dresden, 11.-14.05.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocP 132

doi: 10.3205/14dgnc528, urn:nbn:de:0183-14dgnc5288

Published: May 13, 2014

© 2014 Hartmann et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

Text

Objective: Cervical multilevel corpectomy is a widespread procedure, but recommendations when to perform a supplemental dorsal fixation are lacking. This study evaluates ex vivo the range of motion (RoM) to characterize the stability and the need of an additive dorsal fixation after cervical mono-, bi- or multilevel corpectomies (CE) for elucidating biomechanical differences between anterior-only and additive dorsal instrumentation.

Method: 12 human cervical cadaveric spines (C2-Th1) were loaded in a spine tester with pure moments of 1.5Nm in lateral bending (LB), flexion/extension (FE) and axial rotation (AR) followed by two cyclic loading periods. After each cyclic loading session flexibility tests were performed for the anterior-only (group_1, 6 specimens) and the circumferential (group_2, 6 specimens) instrumentation. The following states were tested: (a) intact, (b) 1-, (c) 2- and (d) 3-level corpectomies with and without dorsal fixations, (e.1) cyclic loading of group_1; (e.2) cyclic loading of group_2.

Results: The mean age of the specimens was 83±12 years with BMD of 194mg/cm³ (±64mg/cm3). In the flexibility tests all 360° instrumentations showed a significant decrease in ROM compared to the intact state and the anterior-only instrumentations regardless of the level resected and the direction of movement (all p<0.05). Compared to the intact, a supplemental dorsal instrumentation after 3-level CE decreased the ROM to 12% (±10%), 9% (±12%) and 22% (±18%) in LB, FE and AR, respectively. Whereas the anterior-only construct outperformed the intact state only in FE with a significant ROM reduction of 57% (±35%), 60% (±27%) and 62% (±35%) for 1-, 2- and 3-level CE, respectively. In LB and AR the 3-level CE with anterior-only instrumentation had the same stabilization potential as the intact state (94% (±36%) and 106% (±52%) of intact; respectively; p>0.05). Two specimens (one of each group) exhibited screw/plate displacement and cage dislocation before cyclic loading period and one specimen (group_1) during the second cyclic loading period.

Conclusions: A 3-level corpectomy with an anterior-only construct shows an increased instability which may lead to a high failure rate (screw pullout/ toggling, graft or plate displacement). A 360° instrumentation stabilizes the corpectomies but necessitates a second approach. From a biomechanical point of view in selected patients a 2-level corpectomy with a dorsal instrumentation already seems to be useful to decrease the complication rate.