Purpose: Subaxial unilateral facet dislocation requires immediate reduction; however, cases of failure with reduction have also been reported. We analyzed the factors preventing closed traction reduction and attempted to determine the efficacy and indications of closed traction reduction. Materials and Methods: We selected 26 patients, 17 men and nine women. The average age of the patients in selected group was 49 years (20-69 years). Each patient was first treated with Gardner head traction and closed traction reduction. Each patient was checked for the degree of locking of the dislocated segment, intervertebral disc herniation, the degree of contralateral facet joint subluxation, and accompanied fracture. The effect of the location of the injured segment, age, and sex on closed reduction traction was analyzed. Results: A high rate of unsuccessful closed traction reduction was observed for patients with more than 50% locking of the dislocated facet joint (p=0.039). Intervertebral disc herniation, the degree of contralateral facet joint subluxation, facet joint fracture, and pedicle and lamina fracture were unrelated to the success of closed traction reduction. The location of dislocation and sex showed no statistically significant relevance to failure of closed traction reduction. A high rate of failure was observed for patients younger than 40 years. Of the 26 patients, closed traction reduction was successful for 12 and unsuccessful for 14. Conclusion: For patients whose degree of locking of the dislocated facet joint is less than 50%, closed traction reduction using skull traction is considered effective, however, for patients younger than 40 years or with more than 50% locking of the dislocated facet, prompt reduction under general anesthesia and subsequent appropriate surgery is considered beneficial.
Supersonic jet technology using high pressures has been popularly utilized in diverse industrial and engineering areas related to working fluids. In this study, to consider the effects of a shock wave caused by supersonic jet flow from a high pressure pipe, the SST turbulent flow model provided in the ANSYS FLUENT v.16 was applied and the flow characteristics of the pressure ratio and Mach number were analyzed in accordance with the working fluids (air, oxygen, and hydrogen). Before carrying out CFD (Computational Fluid Dynamics) analysis, it was presumed that the inlet gas temperature was 300 K and pressure ratio was 5 : 1 as the boundary conditions. The density function was derived from the ideal gas law and the viscosity function was derived from Sutherland viscosity law. The pressure ratio along the ejection distance decreased more in the lower density working fluids. In the case of the higher density working fluids, however, the Mach number was lower. This shows that the density of the working fluids has a considerable effect on the shock wave. Therefore, the reliability of the analysis results were improved by experiments and CFD analysis showed that supersonic jet flow affects the shock wave by changing shape and diameter of the jet, pressure ratio, etc. according to working fluids.
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