Primary stability of pedicle screws depends on the screw positioning and alignment.

Background Context: There is no universal consensus regarding the biomechanical aspects and relevance on the primary stability of misplaced pedicle screws.

Purpose: The study is aimed to the determination of the correlation between axial pullout forces of pedicle screws with the possible screw misplacement, including mild and severe cortical violations.

Methods: Eighty-eight monoaxial pedicle screws were implanted into 44 porcine lumbar vertebral bodies, paying attention on trying to obtain a wide range of placement accuracy.