OBJECTIVES Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, co...

STUDY DESIGN Cadaveric biomechanical study. OBJECTIVE To determine fatigue behavior of cortical bone trajectory (CBT) pedicle screws. SUMMARY OF BACKGROUND DATA Cortical bone trajectory screws have been becoming popular in spine surgery; however, the long-term fatigue behavior of the new CBT screws remains understudied and limitations not well defined. METHODS Twelve vertebrae from six ca...

BACKGROUND CONTEXT Achieving solid implant fixation to osteoporotic bone presents a clinical challenge. New techniques and devices are being designed to increase screw-bone purchase of pedicle screws in the lumbar spine via a novel cortical bone trajectory that may improve holding screw strength and minimize loosening. Preliminary clinical evidence suggests that this new trajectory provides scr...

OBJECTIVE Polyaxial pedicle screws are a safe, useful adjunct to transpedicular fixation. However, the large screw head size can cause soft tissue irritation, high rod positioning, and facet joint injury. However, the mechanical resistance provided by small and low profile pedicle screws is very limited. We therefore developed a novel, low profile pedicle screw using grooving and blasting treat...

BACKGROUND Pedicle screw pullout due to poor bone quality, mainly caused by osteoporosis, is a common problem in spine surgery. Special implants and techniques, especially PMMA augmentation, were developed to improve the fixation of pedicle screws. PMMA injection into a pilot hole or through a screw involves the same risks as vertebroplasty or kyphoplasty, regardless of the technique used. Espe...

STUDY DESIGN Biomechanical analysis. OBJECTIVE To determine the relative strengths of 2 different forms of revision spinal instrumentation using a validated, constant load, cyclic testing mechanism. SUMMARY OF BACKGROUND DATA Spinal fusion with instrumentation procedures are on the rise. As such, so are revision procedures. A few studies have looked at revision instrumentation techniques. B...

BACKGROUND Incorrect placement of pedicle screws may lead to neurovascular injury, so the position is important for the reduction of spinal fractures. CT-based image-guided surgery has been promoted as a means to theoretically improve the accuracy of pedicle screw placement. Patients who underwent CT-based navigation-assisted pedicle screw fixation for thoracic or lumbar fractures were reviewed...

STUDY DESIGN Retrospective study. PURPOSE To analyze the quantitative anatomy of C7 vertebra for insertion of lateral mass screws and pedicle screws in Southern Chinese patients. OVERVIEW OF LITERATURE C7 lateral mass is smaller when compared to other subaxial cervical levels, which limits the length of lateral mass screws that can be used. Some studies have suggested pedicle screws for bet...

AIM One of the most common problems with transpedicular screws is screw pullout. This study was conducted to measure the pullout strengths of newly designed transpedicular screws. MATERIAL AND METHODS The design of the three group screws were conical cored standard pedicle screw (Type A), dual threaded pedicle screw (Type B), dual core and dual threaded pedicle screw (Type C), respectively. P...

AIM To determine whether translaminar facet screws can provide stability equivalent to pedicle screws in two-level anterior lumbar interbody fusion. MATERIAL AND METHODS We performed a biomechanical study using 12 fresh human lumbar spines and tested intact spine, stand-alone two-level ALIF and anterior fusion augmented with pedicle screws or translaminar facet screws under 400N ...