Search results for "NICS"
showing 10 items of 15025 documents
Estimation of structural and geometrical properties of cortical bone by computerized tomography in 78-year-old women
2009
The structural and geometrical properties of the tibia shaft were investigated at two sections by means of computerized tomography (CT) in 78-year-old women with high (n = 19) and low (n = 17) calcaneal bone mineral density (BMD, g/cm3) previously measured by 125I-photon absorption. The high BMD group had a 20-21% higher tibial BMD and 9-12% higher bone cross-sectional area than was observed in the low BMD group. The distribution of bone mass indicated that the low BMD group had lost bone mainly from the endosteal surface, especially in the anterior part of the tibia. However, both groups had a similar basic pattern of mass distribution at the measured sections. The high BMD group had highe…
Biomechanical testing of different posterior fusion devices on lumbar spinal range of motion.
2019
Abstract Background Recent minimal-invasive posterior fusion devices are supposed to provide stability and obtain fusion in combination with interbody cages in the instrumented segment. The aim of the present study is to evaluate the primary stability of two minimal-invasive posterior prototypes compared to an established spinous process plate and standard pedicle screw instrumentation. Methods Seven fresh frozen human cadaver lumbar spines (L2–L5) were tested in a spinal testing device with a moment of 7.5 Nm. Spinal stability was determined as mean range of motion (RoM) in the segment L3/L4 during extension-flexion, lateral bending and axial rotation. The RoM was measured during five cond…
Load Distribution in the Lumbar Spine During Modeled Compression Depends on Lordosis.
2021
Excessive or incorrect loading of lumbar spinal structures is commonly assumed as one of the factors to accelerate degenerative processes, which may lead to lower back pain. Accordingly, the mechanics of the spine under medical conditions, such as scoliosis or spondylolisthesis, is well-investigated. Treatments via both conventional therapy and surgical methods alike aim at restoring a “healthy” (or at least pain-free) load distribution. Yet, surprisingly little is known about the inter-subject variability of load bearings within a “healthy” lumbar spine. Hence, we utilized computer tomography data from 28 trauma-room patients, whose lumbar spines showed no visible sign of degeneration, to …
Kinematics of Cervical Spine during Rowing Ergometer at Different Stroke Rates in Young Rowers: A Pilot Study
2022
Background: Research on biomechanics in rowing has mostly focused on the lumbar spine. However, injuries can also affect other body segments. Thus, the aim of this pilot study was to explore any potential variations in the kinematics of the cervical spine during two different stroke rates on the rowing ergometer in young rowers. Methods: Twelve young rowers of regional or national level were recruited for the study. The experimental protocol consisted of two separate test sessions (i.e., a sequence of 10 consecutive strokes for each test session) at different stroke rates (i.e., 20 and 30 strokes/min) on an indoor rowing ergometer. Kinematics of the cervical spine was assessed using an iner…
Correlation of Tibial Low-Frequency Ultrasound Velocity with Femoral Radiographic Measurements and BMD in Elderly Women
2009
The ultrasonic axial transmission technique has been proposed as a method for cortical bone characterization. Using a low enough center frequency, Lamb modes can be excited in long bones. Lamb waves propagate throughout the cortical bone layer, which makes them appealing for characterizing bone material and geometrical properties. In the present study, a prototype low-frequency quantitative ultrasonic axial transmission device was used on elderly women (n = 132) to investigate the relationships between upper femur geometry and bone mineral density (BMD) and tibial speed of sound. Ultrasonic velocities (V) were recorded using a two-directional measurement set-up on the midtibia and compared …
The role of biosilica in the osteoprotegerin/RANKL ratio in human osteoblast-like cells
2010
Abstract Earlier studies have demonstrated that biosilica, synthesized by the enzyme silicatein, induces hydroxyapatite formation in osteoblast-like SaOS-2 cells. Here we study the effect of biosilica on the expressions of osteoprotegerin [OPG] and the receptor activator for NF-κB ligand [RANKL] in the SaOS-2 cell model. We show that during growth of SaOS-2 cells on biosiliceous matrices hydroxyapatite formation is induced, while syntheses of cartilaginous proteoglycans and sulfated glycosaminoglycans are down-regulated. Furthermore, quantitative real-time RT-PCR analysis revealed a strong time-depended increase in expression of OPG in biosilica exposed SaOS-2 cells while the steady-state e…
Residual Stress Effects on Fatigue Crack Growth in Ti-6Al-4V Friction Stir Welds
2008
Recent studies have illustrated a predominant role of the residual stress on the fatigue crack growth in friction stir welded joints. In this study, the role of the residual stress on the propagation of fatigue cracks orthogonal to the weld direction in a friction stir welded Ti-6Al-4V joint was investigated. A numerical prediction of the fatigue crack growth rate in the presence of the residual stresses was carried out using AFGROW software; reasonable correspondence between the predictions and the experimental results were observed when the effects of residual stress were included in the simulation.
Comparison of frictional resistance between passive self-ligating brackets and slide-type low-friction ligature brackets during the alignment and lev…
2019
Background To compare the frictional resistance between passive self-ligating brackets and conventional brackets with low-friction ligature under bracket/archwire and root/bone interface during dental alignment and leveling. Material and methods A tridimensional model of the maxilla and teeth of a patient treated with conventional brackets, and slide ligatures was generated employing the SolidWorks modeling software. SmartClip self-ligating brackets and Logic Line conventional brackets were assembled with slide low-friction ligatures, utilizing archwires with different diameters and alloys used for the alignment and leveling stage. Friction caused during the bracket/archwire interface and s…
Dynamic Gait Parameters in Patients With Nonunion of the Tibia Following Treatment With the Ilizarov Method.
2020
Abstract The purpose of this study was a comprehensive assessment of the dynamic parameters of gait in patients who underwent Ilizarov treatment for nonunion of the tibia. The experimental group consisted of 24 individuals treated with the Ilizarov method for nonunion of the tibia. The control group comprised 31 healthy individuals, matched for BMI, sex, and age. The dynamic gait parameters in patients and in the control group were measured with a Zebris pedobarographic platform. The treatment group and the control group showed statistically significant differences in terms of the following gait parameters: maximum force during braking nonoperated-limb (NOL), time maximum force during braki…
Comparison between the directly measured achilles tendon force and the tendon force calculated from the ankle joint moment during vertical jumps.
1988
Summary The purpose of this study was to compare the relationship between the achilles tendon force and the tendon force estimated from the ankle joint moment (EATF) during vertical jump. A healthy male subject performed the following jumps on the force platform: (a) maximal vertical jump from a squat position without counter-movement; (b) maximal vertical jump from an erect standing position with a preliminary counter-movement; (c) repetitive submaximal hopping on the spot with preferred frequency. The achilles tendon force was measured directly with an implanted tendon transducer in all jumping conditions. In addition the joint moment obtained from the film and ground reaction force was u…