The Influence of Thread Tap Mismatch on Pedicle Screw Pullout Strength.

Journal: Revista Brasileira De Ortopedia
Published:
Abstract

Objective  We aimed to study the "in vitro" pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw, SpineGuard Inc, Boulder, Colorado, USA), a screw designed to be inserted using a direct insertion technique. Methods  Dynamic Surgical Guidance Screws of 5.5 and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16g/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 with line-to-line tapping. Conclusion  Dynamic Surgical Guidance Screw showed the highest pullout strength after its insertion without pilot hole and tapping.

Authors
Rômulo Pinheiro, Raffaello De Miranda, Antonio Shimano, Thibault Chandanson, Keri George, Helton L Defino
Relevant Conditions

Spinal Fusion