DIRECT PEDICLE SCREW INSERTION PULLOUT STRENGTH

OBJECTIVE: Study the in vitro pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw), a screw pedicle designed to be inserted using a direct insertion technique. METHODS: DSG Screws of 5.5 mm and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16 g/cm(3)). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. RESULTS: Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared to line-to-line tapping. CONCLUSION: DSG Screw showed the highest pullout strength after its insertion without pilot hole and tapping. Level of Evidence V, Expert Opinion.