INTRODUCTION: Osteoporotic fracture is one of the commonest geriatric orthopaedic problems. The deterioration in microarchitecture and decrease in bone mineral density (BMD) in osteoporotic bone reduce its “holding power” to implants. Subsequently, osteoporotic fractures are difficult to be fixed and remain major challenge to surgeons (1). Intensive in vivo studies are necessary for testing the...

Paper focuses on biomechanics, specifically on locking cortical bone screws in angularly stable plates used for the treatment of bone fractures in the medical fields of traumatology and orthopaedics. During extraction of titanium-alloy implants, problems are encountered in an effort to loosen some locking bone screws from the locking holes of an angularly stable plate and the subsequent strippi...

BACKGROUND Some nonstemmed hip systems have been developed to avoid stress shielding and aseptic loosening, which are major drawbacks of stemmed hip arthroplasty. Without the stem, the cup over the femoral head can be stabilized by anatomic fitness of the cup interior and mechanical fixation of the auxiliary screws. METHODS Using finite-element method, neck-shaped systems with two bone-cup fi...

INTRODUCTION: Osteosynthesis plates and screws are used in combination to fix complex fractures. These metallic fixation systems are used with success in healthy bone. But when important stresses apply on the bone-screw interface and when bone is weak, failure of the screw fixation may occur. An obvious mean to improve the fixation of a screw is to augment the surrounding bone with cement. Prev...

Up to date, little is known about the repair mode of microdamage in osteonal cortical bone resulting from bone screw implantation. In this study, self-tapping titanium cortical bone screws were inserted into the tibial diaphyses of 24 adult male rabbits. The animals were sacrificed at 1 day, 2 weeks, 1 month and 2 months after surgery. Histomorphometric measurement and confocal microscopy were ...

BACKGROUND The use of an interference fit wedged bone plug to provide fixation in the tibial tunnel when using bone-patellar tendon-bone autograft for anterior cruciate ligament reconstruction offers many theoretic advantages including the potential to offer a more economical and biological alternative to screw fixation. This technique has not been subjected to biomechanical testing. We hypothe...

The physical status of an interference screw fixation in an anterior cruciate ligament (ACL) reconstructive surgery is a crucial factor of success. In this study, the insertion of the interference screw into a tibial bone tunnel, and the advancement of the screw between the tendon strands were investigated using both experimental and computer modeling. The mechanical behavior of the bone and so...

Introduction Pedicle screws are commonly used in posterior internal fixation systems to stabilise the spine for fusion procedures. Rigid fixation systems place high requirements on the load-carrying capacity at the screw-bone interface. Poor bone quality decreases the integrity of this interface, increasing screw micromotion and consequently reducing screw stability and possibly fusion success....

STUDY DESIGN Biomechanical study. PURPOSE To determine the effect of density, insertion angle and reinsertion on pull-out strength of pedicle screw in single and two screw-rod configurations. OVERVIEW OF LITERATURE Pedicle screw pull-out studies have involved single screw construct, whereas two screws and rod constructs are always used in spine fusions. Extrapolation of results using the si...

Progressive loosening of bone fixation screws is a well-documented phenomenon, induced by stress shielding and subsequent adaptive bone remodeling which results in bone loss around the screw. A set of two-dimensional computational (finite element) models was developed in order to test the effect of various engineering designs of fixation screws on the predicted screw-bone stress transfer, and c...