BACKGROUND There have been numerous studies conducted to investigate the pullout force of pedicle screws in bone with different material properties. However, fewer studies have investigated the region of effect (RoE), stress distribution and contour pattern of the cancellous bone surrounding the pedicle screw. METHODS Screw pullout experiments were performed from two different foams and the c...

The complete relationship between the pullout load and the displacement of a fibre when it pulls out of the matrix serves as an important parameter in the design of composite materials. Many analytical models for the prediction of the behaviour of composite materials are based on the assumption of a constant friction load between the fibre and the matrix, regardless of the displacement of the f...

PURPOSE. To evaluate the insertion torque and pullout strength of pedicle screws with or without repositioning. METHODS. 20 fresh porcine lumbar vertebrae of similar size were used. The entry point was at the site just lateral and distal to the superior facet joint of the vertebra, and to a depth of 35 mm. A 6.2-mm-diameter, 35-mm-long pedicle screw was inserted parallel to the superior end pla...

INTRODUCTION Early-stage pullout is a common problem for surgeons during the fixation of osteoporotic bones. Poor bone quality limits the use of pedicle screws for patients with osteoporosis. In this study, the researchers investigated the effects of hole and gap position and type on the pullout strength of cannulated screws. METHODS Seven different designs were tested, including a control gr...

In this study, the bond stress distribution and bond–slip model of steel bars iron tailing sand recycled aggregate concrete (ITRAC) were investigated using central pullout tests on 33 ITRAC bonded specimens. The results show three failure modes for specimens: splitting, pullout, splitting–pullout. Compared with maximum strength nature (NAC), specimens increased by 23.12% 6.08–23.96%, respective...

Molecular dynamics (MD) simulations under transverse shear, uniaxial compression, and pullout loading configurations are reported for multiwall carbon nanotubes (MWCNTs) with different fraction of interwall sp3 bonds. The interwall shear coupling in MWCNTs is shown to have a strong influence on load transfer and compressive load carrying capacity. A new continuum shear-coupled-shell model is de...