Spinous Process Wiring Versus Lateral Mass Fixation for the Treatment of Anterior Cervical Pseudarthrosis: A Biomechanical Comparison

Our objective was to compare the stiffness of lateral mass screws versus two different spinous process wiring constructs in a cadaveric model of plated anterior cervical pseudoarthrosis. When treating an anterior plated pseudoarthrosis via a posterior approach, it is unclear whether the added expense, muscle exposure, and risk of lateral mass fixation are justified biomechanically versus a simpler, cheaper, and potentially less morbid wiring technique, because the presence of the anterior plate likely reduces motion over the unplated situation. Seven cadaveric cervical spines were loaded in compression, flexion, extension, lateral bending, and torsion. Each load sequence was applied to: 1) the intact spine; 2) after application of a plated ACDF construct (pACDF); and 3) after the insertion of lateral mass (LM) screws, ‘‘modified’’ triple wiring (TW), or Roger’s wiring (RW), in alternating order for each specimen. For each sequence, load deformation curves and stiffness were obtained. Supplemental LM fixation significantly (p
0.05) increased stiffness versus pACDF in all six modes tested. TW significantly increased stiffness versus pACDF in compression, flexion, and torsion, but not in extension, or lateral bending. RW
significantly increased stiffness versus pACDF only in axial torsion. When comparing LM to the wiring constructs, LM fixation was significantly stiffer than RW in flexion, extension, and lateral bending; LM fixation was stiffer than TW in lateral bending. LM fixation produced the stiffest overall constructs in stabilizing a plated pseudarthrosis ACDF model. It was significantly stiffer in more modes versus RW than TW. (Journal of Surgical Orthopaedic Advances 20(4):220–224, 2011)