PURPOSE Pullout strength of screws is a parameter used to evaluate plate screw fixation strength. However, screw fixation strength may be more closely related to its ability to generate sufficient insertion because stable nonlocked plate-screw fracture fixation requires sufficient compression between plate and bone such that no motion occurs between the plate and bone under physiological loads....

PURPOSE There are few studies on biomechanical evaluation of suture points in repair of root tears. The purpose of this study was to determine the point of greatest pullout strength for root tear repair. MATERIALS AND METHODS A total of 120 fresh porcine medial menisci were obtained. The red-red and red-white zones of the meniscus were divided by two lines designated as lines A and B (groups ...

The aim of the study was to evaluate mechanical behavior of implants inserted in three substrates, by measuring the pullout strength and the relative stiffness. 32 implants (Master Porous-Conexao, cylindrical, external hexagon, and surface treatment) were divided into 4 groups (n = 8): pig rib bone, polyurethane Synbone, polyurethane Nacional 40 PCF, and pinus wood. Implants were installed with...

In this paper, the inelastic damage process in Engineered Cementitious Composites (ECC) in the high stress concentration zone adjacent to the head of an embedded anchor under tensile load was examined experimentally and numerically. An FEM model together with a tensile strain-hardening material model of ECC was developed to simulate the damage process leading to final failure. Experimental obse...

STUDY DESIGN The strength effects of a pedicle screw-rod system supplemented with a novel cross-link configuration were biomechanically evaluated in porcine spines. PURPOSE To assess the biomechanical differences between a conventional cross-link pedicle screw-rod system versus a novel cross-link instrumentation, and to determine the effect of the cross-links. OVERVIEW OF LITERATURE Transve...

An important concept in bone mechanics is that osteons influence mechanical properties in several ways, including contributing to toughness and fatigue strength by debonding from the interstitial matrix so as to "bridge" developing cracks. Observations of "pulled out" osteons on fracture surfaces are thought to be indicative of such behavior. We tested the hypothesis that osteon pullout varies ...

OBJECTIVES This study aims to assess five different cortical screw types using artificial femurs, under equated testing conditions. MATERIALS AND METHODS We investigated the maximum force needed to cause deformation at screw-bone interface using fourth generation composite femurs by conducting separate pullout tests for each screw type. We normalized obtained results with traditional methods ...

The porcine model is frequently used during development and validation of new spinal devices, because of its likeness to the human spine. These spinal devices are frequently composed of pedicle screws with a reputation for stable fixation but which can suffer pullouts during preclinical implantation on young animals, leading to high morbidity. With a view to identifying the best choices to opti...

OBJECTIVE To evaluate the influence of pilot hole tapping on pullout resistance and insertion torque of pedicle screws with a conical core. METHODS Mechanical tests using a universal testing machine were performed on pedicle screws with a conical core that were inserted into pedicles in the fifth lumbar vertebra of calves. The insertion torque was measured using a torque meter with a capacity...

Patients with pathologic hip fractures or impending pathologic proximal femur fractures are at a high risk for developing bone cement implantation syndrome during cemented femoral arthroplasty. Comorbid conditions of patients who sustain these fractures, including cardiopulmonary compromise and permeable, highly vascular bone related to metastatic disease, put them at risk for sudden death. Red...