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RISS 인기검색어
- 검색키워드
- 저자 : Yoshinari NAKAMURA (검색결과 4 건)
- 무료
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Curved Periacetabular Osteotomy for the Treatment of Dysplastic Hips
Masatoshi Naito,Yoshinari Nakamura 대한정형외과학회 2014 Clinics in Orthopedic Surgery Vol.6 No.2
Curved periacetabular osteotomy (CPO) was developed for the treatment of dysplastic hips in 1995. In CPO, the exposure of osteotomy sites and osteotomy of the ischium are made in the same manner as Bernese periacetabular osteotomy, and iliac and pubic osteotomies are performed in the same manner as rotational acetabular osteotomy. We studied the dynamic instabilities of 25 dysplastic hips before and after CPO using triaxial accelerometry. Overall magnitude of acceleration was significantly decreased from 2.30 ± 0.57 m/sec2 preoperatively to 1.55 ± 0.31 m/sec2 postoperatively. Pain relief and improvement of acetabular coverage resulting from acetabular reorientation seem to be related with reduction of dynamic instabilities of dysplastic hips. Isokinetic muscle strengths of 24 hips in 22 patients were measured preoperatively and after CPO. At 12 months postoperatively, the mean muscle strength exceeded the preoperative values. These results seem to be obtained due to no dissection of abductor muscles in CPO. The preoperative presence of acetabular cysts did not influence the results of CPO. An adequate rotation of the acetabular fragment induced cyst remodeling. Satisfactory results were obtained clinically and radiographically after CPO in patients aged 50 years or older. CPO alone for the treatment of severe dysplastic hips classified as subluxated hips of Severin group IV-b with preoperative CE angles of up to –20° could restore the acetabular coverage, weight-bearing area and medialization of the hip joint. CPO without any other combined procedure, as a treatment for 17 hips in 16 patients with Perthes-like deformities, produced good mid-term clinical and radiographic results. We have been performing CPO in conjunction with osteochondroplasty for the treatment of acatabular dysplasia associated with femoroacetabular impingement since 2006. The combined procedure has been providing effective correction of both acetabular dysplasia and associated femoral head-neck deformities without any increased complication rate. We have encountered an obturator artery injury in one case and two intraoperative comminuted fractures. Although serious complications such as motor nerve palsy, deep infection, necrosis of the femoral head or acetabulum, and delayed union or nonunion of the ilium were reported, such complications have never occurred in our 700 cases so far.
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Experimental and numerical flow analysis in hydraulic vane pump
Junichi SUEMATSU,Tetsuhiro TSUKIJI,Mariko WATANABE,Shinji YAKABE,Hirohito WATANABE,Yoshinari NAKAMURA,Kazunari SUZUKI 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
The purpose of this study is to conduct a three dimensional flow analysis of a hydraulic vane pump by using computational fluid dynamics (CFD), to evaluate an accuracy of volumetric flow rate in CFD compared to experimental value and to examine a influence of the evaporation coefficient and condensation coefficient in Zwart–Gerber–Belamri cavitation model to pressure in a vane chamber. In this study, standard k-ε turbulent model with the Zwart–Gerber–Belamri cavitation model is used to estimate the cavitating flow in vane pump. In CFD, two notch models are used. From results of experiments and CFD analysis of volumetric flow rate, there is little difference between the experiments and CFD results in the low speed range. However, for high speed range, in a case with no cavitation model, the CFD results of volumetric flow rate are different from the experimental ones. On the other hand, in the case with cavitation model, those agree with the experimental values. In this case, the error of volumetric flow rate is less than 1% in the low speed range and less than 2.5% in the high speed range. From CFD results of pressure fluctuation in a vane chamber when the evaporation coefficient and condensation coefficient in the cavitation model are varied, the surge pressure can be seen in a vane chamber. In conclusion, it could be considered that the CFD calculation with cavitation model is sufficiently accurate in volumetric flow rate. In addition, as the evaporation coefficient becomes large, amplitude of the pressure fluctuation in a vane chamber after a surge pressure becomes large, as the condensation coefficient becomes large, the surge pressure in a vane chamber becomes low.
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