SUBSTITUTION OF TRANSPEDICULAR SCREWS BY HOOK CLAWS IN A VERTEBRECTOMY MODEL

At times one pedicle screw cannot be used in a posterior construct bec ause of morphometric reasons or when the pedicle is fractured intraope ratively. It is not clear from the literature whether and to what exte nt a construct's stability is compromised by substituting a hook claw for one pedicle screw. A synthetic vertebra model using a hook claw in lieu of a pedicle screw in a compressive and torsional mechanical stu dy is evaluated. Isola screw-based constructs varying in the number of pedicle screws and hook claws were used. To recreate a realistic clin ical scenario, transverse connectors and a Harms cage were used as wel l. In compression. substituting screws with claws did not substantiall y change the stiffness, whereas substituting one or two pedicle screws with one or two hook claws significantly reduced torsional stiffness. We conclude that using one or two hook claws is a viable alternative for pedicle screws when the latter cannot be used in a clinical situat ion, especially as an adjunct when the anterior column is reconstructe d.