BACKGROUND The pullout strength of pedicle screws is influenced by many factors, including diameter of the screws, implant design, and augmentation with bone cement such as PMMA. In the present study, the pullout strength of an innovative fenestrated screw augmented with PMMA was investigated and was compared to unaugmented fenestrated, standard and dual outer diameter screw. METHODS Twenty f...

Twenty-seven paired human cadaveric knee specimens were used to determine the effect of surgical technique and various interference screw parameters on the pullout strength of patellar tendon femoral bone blocks. The study compared the fixation strength of endoscopically inserted and conventional "rear-entry" screws of different diameters and lengths. In all tests the most frequent mode of fail...

Study Design Biomechanical analysis of lateral mass screw pullout strength. Objective We compare the pullout strength of our bone cement-revised lateral mass screw with the standard lateral mass screw. Methods In cadaveric cervical spines, we simulated lateral mass screw "cutouts" unilaterally from C3 to C7. We salvaged fixation in the cutout side with polymethyl methacrylate (PMMA) or Cortoss ...

During acupuncture treatments, acupuncture needles are manipulated to elicit the characteristic "de qi" reaction widely viewed as essential to acupuncture's therapeutic effect. De qi has a biomechanical component, "needle grasp," which we have quantified by measuring the force necessary to pull an acupuncture needle out of the skin (pullout force) in 60 human subjects. We hypothesized that pull...

In this paper, results obtained in both conventional and finite element analysis of straight and belled anchor shafts subjected to a pullout force are presented. In numerical analysis, it is assumed that no drainage takes place during the anchor pullout. Comparisons between two conventional methods of analysis for ultimate pullout load and the results obtained by the finite element analysis are...

Antegrade telescoping rods have been introduced for use in pediatric patients with osteogenesis imperfecta (OI) to decrease the incidence of long-bone fractures and to correct and prevent deformities. Recent studies have documented failures of telescoping intramedullary rods due to inadequate distal fixation. The purpose of this study was to evaluate the pullout strength of distal fixation of t...

Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimat...

The purpose of this study was to determine the change of fixation strength after adjusting the height of polymethylmethacrylate (PMMA)-augmented pedicle screws.Cement-augmented cannulated pedicle screws with or without PMMA augmentation with a radial hole in the distal third of the screw thread were inserted into synthetic bone blocks used to model osteoporosis. Screws were left unchanged (in s...

pedicle screws provide rigid fixation for instabilities in the lumbar and lumbosacral spine. anatomical consideration and potential risk of neurologic complications are the reasons to hesitate using pedicle screws in the thoracic spine. twenty moulages similar to human vertebrae were instrumented with cotrel-dubousset (cd) system pedicle screw by intratransverse process, extrapedicular and intr...

OBJECT In 2009, Santoni et al. reported cortical bone trajectory (CBT) as a method of inserting pedicle screws to obtain more solid fixation, and proposed the use of cortical trajectory screws with a more closely placed thread (cortical screws) for CBT. Since the entry trajectory in CBT differs from that in the traditional trajectory, it is unclear whether the increased strength derives from th...