Search results for "Crew"
showing 10 items of 93 documents
Effects of rectilinear acceleration and optokinetic and caloric stimulations in space.
1984
During the flight of Spacelab 1 the crew performed a number of experiments to explore changes in vestibular function and visual-vestibular interactions on exposure to microgravity. Measurements were made on the threshold for detection of linear oscillation, vestibulo-ocular reflexes elicited by angular and linear movements, oculomotor and posture responses to optokinetic stimulations, and responses to caloric stimulation. Tests were also conducted on the ground, during the 4 months before and on days 1 to 6 after flight. The most significant result was that caloric mystagmus of the same direction as on the earth could also be evoked in the weightless environment.
European vestibular experiments on the Spacelab-1 mission: 1. Overview.
1986
During the flight of Spacelab-1 a series of vestibular experiments was performed on the crew by a group of European investigators. Control experiments were carried out on the same subjects pre- and postflight. The tests included caloric stimulation of the ears, threshold measurements of response to linear acceleration, motion sickness provocative stimuli, vestibulo-ocular reflexes during linear and angular stimulation, estimation of the subjective vertical (luminous line measurements) and static ocular counterrotation at various tilt angles. The caloric experiment proved the existence of a nonthermoconvective mechanism of caloric nystagmus in space. Most of the other test results point to a…
Cement augmentation for trochanteric fracture in elderly: A systematic review()
2021
Abstract Background Cement augmentation of internal fixation of hip fracture has reported to improve fracture stability in osteoporotic hip fractures, reducing the risk of cut-out of the sliding screw through the femoral head. The purpose of present study was to perform a systematic literature review on the effects of augmentation technique in patients with osteoporotic hip fractures. Material and methods A comprehensive literature search was systematically performed to evaluate all papers published in English language included in the literature between January 2010 and July 2020, according to the PRISMA 2009 guidelines. In vivo and in vitro studies, case reports, review articles, cadaveric…
Rates of Upper Facet Joint Violation in Minimally Invasive Percutaneous and Open Instrumentation: A Comparative Cohort Study of Different Insertion T…
2017
Background Minimally invasive pedicle screw placement may have a higher incidence of violation of the superior cephalad unfused facet joint. Study Aims We investigated the incidence and risk factors of upper facet joint violation in percutaneous robot-assisted instrumentation versus percutaneous fluoroscopy-guided and open transpedicular instrumentation. Methods A retrospective study including all consecutive patients who underwent lumbar instrumentation, fusion, and decompression for spondylolisthetic stenosis and degenerative disk disease was conducted between January 2012 and January 2016. All operations were performed by the same surgeon; the patients were divided into three groups acc…
Transverse fracture-dislocation of the sacrum: a diagnostic pitfall and a surgical challenge.
2002
Transverse fracture-dislocations of the sacrum are rare. Associated lesions of the lumbosacral spine as well as neurological injuries are common. Conventional radiographs of the pelvis often fail to clearly visualize the fracture. Delayed diagnosis increases the risk of progressive neurological disfunction. True lateral sacral views and CT-scans with 3-dimensional reconstructions are very helpful in establishing the full extent of the injury. These examinations should be considered in all patients with a history of high energy trauma and clinical signs indicating lumbosacral injury, such as severe low back pain and neurological disturbances of the lower extremities. The management of transv…
In vitro comparison of the efficacy of two fractured implant-prosthesis screw extraction methods: Conventional versus mechanical.
2019
Abstract Statement of problem Implant-supported prostheses may be subject to esthetic, biological, or mechanical complications. Protocols for dealing with these mechanical problems are sparse. Purpose The purpose of this in vitro study was to compare the efficacy of a mechanical system for extracting fractured implant-prosthesis screws with the conventional method. Material and methods A total of 60 screws were divided into 2 groups according to their morphology (flat screws with a smooth shaft and threaded apical area and screws with a completely threaded body) and subjected to fatiguing and static load testing until fracture. The specimens were assigned to 3 operators with varying levels …
Le Fratture di Rotula
2015
Patellar fractures are relatively uncommon, accounting for approximately 1% of all fractures. Non-operative treatment represents the best choice for undisplaced patellar fractures. However, surgery becomes necessary when fractures are displaced by more than 2 mm, and may include open reduction and internal fixation. Accurate reduction and rigid fixation are required in order to allow early knee mobilization and to obtain a better clinical outcome. Several techniques have been described for patellar fracture fixation, such as tension band wiring, interfragmentary screw fixation, and the combination of screw fixation and cerclage. In this article up-to-date diagnosis, classification and treat…
A Locked Intraosseous Nail for Transverse Patellar Fractures: A Biomechanical Comparison with Tension Band Wiring Through Cannulated Screws.
2018
Background Displaced transverse patellar fractures require open reduction and internal fixation. State-of-the-art stabilization techniques are tension band wiring (TBW) using Kirschner wires or cannulated screws. These techniques are associated with high rates of secondary fracture displacement, implant migration, implant prominence, wound-healing disturbances, and the need for implant removal. Recently, a locked intraosseous patellar nail prototype was developed. The aim of the present study was to investigate the biomechanical performance of this nail compared with TBW using cannulated screws. Methods Seven paired fresh-frozen human cadaveric knees were stripped of all soft tissues except…
Screw‐in‐screw fixation of fragility sacrum fractures provides high stability without loosening—biomechanical evaluation of a new concept
2020
Surgical treatment of fragility sacrum fractures with percutaneous sacroiliac (SI) screw fixation is associated with high failure rates. Turn-out is detected in up to 20% of the patients. The aim of this study was to evaluate a new screw-in-screw implant prototype for fragility sacrum fracture fixation. Twenty-seven artificial hemipelvises were assigned to three groups (n = 9) for instrumentation of an SI screw, the new screw-in-screw implant prototype, ora transsacral screw. Before implantation, a vertical osteotomy was set in zone 1 after Denis. All specimens were biomechanically tested to failure in upright position. Validated setup and test protocol were used for complex axial and torsi…
A new tool to improve pedicle screw placement accuracy in navigated spine surgery: A monocentric study
2021
Objective Navigated instrumented spine surgery is burden by a low but significant screw mispositioning risks, respectively, for the 2D imaging system from 15 to 40% and, for the 3D imaging system, ranging from 4.1 to 11.5%. The primary objective of this study was to demonstrate the efficacy of a new "screw-like" tool in order to further decrease pedicle screws mispositioning rate during vertebral navigated spine surgery. Materials and methods Between January and June 2019 an initial case series of 18 patients were enrolled. All patients underwent a pedicle screw fixation, both in thoracic (Th10-Th12) and lumbosacral (L1-S1) spine, using O-arm (Medtronic Navigation, Louisville, Colorado) and…