Influence of screw-cement enhancement on the stability of anterior thoracolumbar fracture stabilization with circumferential instability.

The influence of additional dorsal structure damage on anterior stabilization of a thoracolumbar fracture is still unknown. Screw-cement enhancement can be used to reinforce the stability of anterior instrumentation. We have developed a new anchorage system for fixation of anterior stabilization devices, adapted through geometric optimization and the additional option of cementation after screw insertion. This study examines the question of whether this enhancement is strong enough to enable a single anterior procedure and still compensate for dorsal instability. Various spinal reconstruction procedures were evaluated biomechanically in an increasing ventrodorsal instability model for thoracolumbar fracture stabilization. A biomechanical in vitro study, simulating stabilized defect situations (corporectomy/vertebrectomy) with strut grafting and overbridging instrumentation, was performed on six human T10-L2 cadaveric specimens. The primary stability parameters, range of motion and neutral zone, were evaluated with or without anterior screw-cement enhancement. This was compared with a single conventional anterior stabilization without a dorsal defect (corporectomy). It was also compared with a single anterior, posterior or combined procedure in the presence of additional dorsal structure damage (vertebrectomy). The use of an additional cementable screw dowel enhanced the primary stability of the anterior instrumentation, compensating for dorsal instability. These results are warranted for the clinical use of minimally open or endoscopic techniques, creating the highest possible primary stability while performing a single anterior enhanced instrumentation with a tissue-preserving approach.