UNLABELLED INTRODUCTION Symptomatic spondylolysis is always challenging to treat because the pars defect causing the instability needs to be stabilized while segmental fusion needs to be avoided. Direct repair of the pars defect is ideal in cases of spondylolysis in which posterior decompression is not necessary. We report clinical results using segmental pedicle-screw-rod fixation with bone...

We analyze screw, edge and mixed screw-edge dislocations in monochromatic light waves. Methods for the experimental dete~nation of the topological charge value and helicity of screw dislocations are elaborated. By use of computer-synthesized binary gratings waves with edge and mixed screw-edge disl~ations were obtained and studied ~xpe~mentally. The transformation of a mixed screw-edge distocat...

BACKGROUND Tibial aperture fixation with a bioabsorbable interference screw is a popular fixation method in anterior cruciate ligament reconstruction (ACLR). An interference screw containing β-tricalcium phosphate (β-TCP) to improve bony integration and biocompatibility was recently introduced. This study aims to compare the clinical outcomes and radiological results of tunnel enlargement effec...

antagonists are a common orthodontic problem, especially in adult patients. To facilitate prosthodontic restoration in the mandible, the overerupted molars have to be intruded, which tends to cause the adjacent teeth to extrude when conventional appliances are used. In recent years, temporary anchorage devices (TADs) have allowed orthodontists to overcome these drawbacks while avoiding unesthet...

The degree of mobility of a given linkage depends upon the order of its screw system, whereby a loop with six joint freedoms may be related to its reciprocal screw system, a single screw axis with an associated pitch. It has been postulated that this reciprocal screw can provide an alternative means of identifying its parent linkage, and an investigation in this respect has been recently carrie...

PURPOSE During the early postoperative period, the stability of the fixation of a hamstring graft to the bone tunnel is the primary factor in limiting rehabilitation. The aim of this study was to evaluate if the initial fixation strength of a new suspension screw is comparable to that of the biodegradable interference screw fixation technique in the hamstring reconstruction of the anterior cruc...

Fixation with a dynamic hip screw (DHS) is one of the most common methods for stabilizing intertrochanteric fractures, except for unstable and reverse oblique fracture types. However, failure is often observed in osteoporotic patients whereby the lag screw effectively 'cuts out' through the weak bone. Novel anti-migration blades have been developed to be used in combination with a lag screw ('B...

BACKGROUND Lag screw cut-out failure following fixation of unstable intertrochanteric fractures in osteoporotic bone remains an unsolved challenge. This study tested if resistance to cut-out failure can be improved by using a dual lag screw implant in place of a single lag screw implant. Migration behavior and cut-out resistance of a single and a dual lag screw implant were comparatively evalua...

This work is concerned with the development of numerical techniques devoted to the simulation of the flow of a polymer melt in mixing processes such as twin-screw extrusion. In mixing or twin extrusion process simulation, the absence of symmetry of the moving boundaries (the screws) implies that their rigid body motion has to be taken into account by using a special treatment. In this study, we...

BACKGROUND Two types of implants used for the surgical fixation of extracapsular hip fractures are cephalocondylic intramedullary nails, which are inserted into the femoral canal proximally to distally across the fracture, and extramedullary implants (e.g. the sliding hip screw). OBJECTIVES To compare cephalocondylic intramedullary nails with extramedullary implants for extracapsular hip frac...