MULTISEGMENTAL ANTERIOR STABILIZATION OF THE LUMBAR SPINE - A COMPARATIVE BIOMECHANICAL INVESTIGATION

The stabilitiy provided by three anterior spinal fixation devices (VDS, TSRH, CDH) designed for multisegmental instrumentation have been studied in an in-vitro model using L1-L5 sections of six human cadaveric spines for each instrumentation. Three-dimensional measurement of rotation and translation for the intact and instrumented spine under physiological loads in flexion/extension, lateral bending, and axial rotation were determined. After measuring the intact spine the destabilization was performed by complete intersection of the intervertebral disc, all spines were instrumented for 3 segments. TSRH was found to be significantly (p < 0,05) higher in stiffness in flexion/extension and torsion than VDS. In bending there was no statistical difference. In all tests CDH was significantly more stable than VDS. In flexion/extension it proved higher in stiffness than TSRH, no statistical difference was observed in bending and rotation.