In this paper, a modular designed automatic screw tightening shaft system, which is based on enhanced variable gain PID control, is proposed. Designed for the autonomous screw tightening operation, the screw tightening shaft enjoys huge potential for industry application. The screw tightening shaft and the screw tightening process are both mathematically modeled as an uncertain feedback system ...

The purpose of this study was to determine the influence of gender, screw design, and the approach on maximal screw length in scaphoid fracture fixation. Measurements were performed on 3D reconstructions of 20 CT scans of normal scaphoids. A comparison was made between 15 different available screw designs and between volar and dorsal screw placement. The length of the scaphoid along its central...

STUDY DESIGN A prospective self-controlled study. OBJECTIVE The aim of the present study was to compare the application and clinical outcomes of transposterior arch lateral mass screw and lateral mass screw fixation of the atlas in the treatment of atlantoaxial instability. SUMMARY OF BACKGROUND DATA Atlas posterior screw fixation techniques comprise transposterior arch lateral mass screw f...

STUDY DESIGN A biomechanical spine model was used to evaluate the impact of screw design on screw-vertebra interface loading during simulated surgical corrections of adult scoliosis. OBJECTIVES To evaluate differences in screw-vertebra interface forces during adult scoliosis correction between favored angle (FA) screws with extension tabs and standard polyaxial screws while varying deformity ...

BACKGROUND It has been observed clinically that the Z-effect is a potential cause of failure of an intramedullary nail with two cephalic screws. It describes the migration behavior of the cephalic screws in the femoral head. The primary objective was to examine different cephalic screw configurations and test the load distribution between them as a function of their relative placement and their...

BACKGROUND It was reported that expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) could be used to increase screw stability in osteoporosis. However, there are no studies comparing the two kinds of screws in vivo. Thus, we aimed to compare biomechanical and interfacial performances of EPS and PMMA-PS in osteoporotic sheep spine. METHODOLOGY/PRINCIPAL F...

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...

background: at present, there is no consensus on an appropriate treatment modality for intertrochanteric fractures in the elderly with background diseases. the aim of the present study was to compare treatment outcomes of intertrochanteric fractures reduced with dynamic hip screws (dhs) and bipolar hemiarthroplasty in elderly patients with background medical conditions. methods: in this randomi...

The first signs of mobile commerce hype are here. Extremely rapid penetration and growth processes are predicted on the basis of some quick descriptions of mobile technology. The roots of these predictions are often found in markets with a low penetration rate of mobile technology. Nevertheless, it should be clear that without real substance in m-commerce products and services the investments i...

This paper gives an overview on the potentials of numerical simulations for understanding dynamics in laser material processing. After a short introduction into the model, simulation results on several processes like laser beam deep penetration welding, drilling or cutting are presented. Furthermore simulation results are compared with experimentally obtained data.