In vitro biomechanical evaluation of four fixation techniques for distractive–flexion injury stage 3 of the cervical spine. (August 2015)

• Record Type: Journal Article
• Authors: Henriques, Thomas; Cunningham, Bryan W.; Mcafee, Paul C.; Olerud, Claes
• Is Part Of: Upsala journal of medical sciences. Volume 120:Number 3(2015:Sep.)
• Page Start: 198
• Page End: 206
• Publication Date: 2015-08
• Subjects: Medicine -- Periodicals; Medicine -- Periodicals; Electronic journals; 610.5
• Languages: English
• ISSNs: 0300-9734

Abstract

<abstract> <title>Abstract</title> <p> <bold> <italic>Purpose.</italic> </bold> 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.</p> <p> <italic>Methods.</italic> 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.</p> <p> <italic>Results.</italic> 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 (<italic>p</italic> > 0.05). The anterior plate combined with posterior wire technique improved flexion–extension stiffness (<italic>p</italic> = 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 (<italic>p</italic> < 0.05).</p> <p> <italic>Conclusions.</italic> 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.</p> </abstract>