In vitro biomechanical evaluation of four fixation techniques for distractive–flexion injury stage 3 of the cervical spine

  • Thomas Henriques Stockholm Spine Center, Löwenströmska Hospital, Upplands Väsby, Sweden
  • Bryan W. Cunningham Orthopaedic Spinal Research Institute, The University of Maryland St. Joseph Medical Center, Baltimore, Maryland, USA
  • Paul C. Mcafee Scoliosis and Spine Center, The University of Maryland St. Joseph Medical Center, Baltimore, Maryland, USA
  • Claes Olerud Department of Orthopaedics, Uppsala University Hospital, Uppsala, Sweden
Keywords: Biomechanical analysis, cervical spine, distractive–flexion injury, internal fixation, transarticular screws, pedicle screws

Abstract

Purpose. Anterior plate fixation has been reported to provide satisfactory results in cervical spine distractive flexion (DF) injuries stages 1 and 2, but will result in a substantial failure rate in more unstable stage 3 and above. The aim of this investigation was to determine the biomechanical properties of different fixation techniques in a DF-3 injury model where all structures responsible for the posterior tension band mechanism are torn.

Methods. The multidirectional three-dimensional stiffness of the subaxial cervical spine was measured in eight cadaveric specimens with a simulated DF-3 injury at C5–C6, stabilized with four different fixation techniques: anterior plate alone, anterior plate combined with posterior wire, transarticular facet screws, and a pedicle screw–rod construct, respectively.

Results. The anterior plate alone did not improve stability compared to the intact spine condition, thus allowing considerable range of motion around all three cardinal axes (p > 0.05). The anterior plate combined with posterior wire technique improved flexion–extension stiffness (p = 0.023), but not in axial rotation and lateral bending. When the anterior plate was combined with transarticular facet screws or with a pedicle screws–rod instrumentation, the stability improved in flexion–extension, lateral bending, and in axial rotation (p < 0.05).

Conclusions. These findings imply that the use of anterior fixation alone is insufficient for fixation of the highly unstable DF-3 injury. In these situations, the use of anterior fixation combined with a competent posterior tension band reconstruction (e.g. transarticular screws or a posterior pedicle screws–rod device) improves segmental stability.

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Published
2015-03-06
How to Cite
Henriques, T., Cunningham, B. W., Mcafee, P. C., & Olerud, C. (2015). <em>In vitro</em&gt; biomechanical evaluation of four fixation techniques for distractive–flexion injury stage 3 of the cervical spine. Upsala Journal of Medical Sciences, 120(3). https://doi.org/10.3109/03009734.2015.1019684
Section
Original Articles