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91.
To analyze the causes and mechanisms affecting the fracture toughness of X80 pipeline steel welded joints against H2S, the fracture toughness of different zones of X80 pipeline steel welded joints in both air and saturated H2S solution was investigated. The fracture toughness of welded joints degraded significantly in the saturated H2S solution, where the crack tip opening displacement (CTOD) characteristic value in the coarse grain heat-affected zone (CGHAZ) and weld metal (WM) was only 8% and 12% of that in air, respectively. However, the sub-critical grain heat-affected zone (SCHAZ) showed better resistance to H2S corrosion, with the CTOD characteristic value reaching 42% of that in air. The resistance of the welded joint to H2S corrosion was sensitive to microstructures. The grain boundary ferrite (GBF) presented in WM, and the angle of grain boundary orientation in CGHAZ was not conducive to hindering crack propagation. Moreover, the formation of the resultant hydrogen cracks owing to the H2S corrosion also reduced the fracture toughness of the welded joint. 相似文献
92.
In the present work, three different woven composite laminates were fabricated using the hand lay-up method. The woven reinforcement fibres were carbon fibres (CFRP), glass fibres (GFRP-W) and (GFRP-R) in combination with epoxy resin. Then, the central notch specimen tensile test (CNT) was used to measure the fracture toughness and the corresponding surface release energy (). Then, the data were compared with the essential work of fracture (we) values based on the stored energy of the body to obtain a new standard fracture toughness test for composite laminates using relatively simple techniques. In addition to an extended finite element model, XFEM was implemented over a central notch specimen geometry to obtain a satisfactory validation of the essential work of fracture concepts. Therefore, the average values of () were measured with CNT specimens 25.15 kJ/m2, 32.5 kJ/m2 and 20.22 kJ/m2 for CFRP, GFRP-W and GFRP-R, respectively. The data are very close as the percentage error for the surface release energy measured by the two methods was 0.83, 4.6 and 5.16 for carbon, glass and random fibre composite laminates, respectively. The data for the fracture toughness of XFEM are also very close. The percentage error is 4.6, 5.25 and 2.95 for carbon, glass and random fibre composite laminates, respectively. Therefore, the fundamental work of the fracture concept is highly recommended as a fracture toughness test for composite laminates or quasi-brittle Material. 相似文献
93.
Rationale:Oblique lumbar interbody fusion (OLIF) is an effective and safe surgical technique widely used for treating spondylolisthesis; however, its use is controversial because of several associated complications, including endplate injury. We report a rare vertebral body fracture following OLIF in a patient with poor bone quality.Patient concerns:A 72-year-old male patient visited our clinic for 2 years with lower back pain, leg radiating pain, and intermittent neurogenic claudication.Diagnoses:Lumbar magnetic resonance imaging revealed L4-5 stenosis.Intervention:We performed OLIF with percutaneous pedicle screw fixation and L4 subtotal decompressive laminectomy. We resected the anterior longitudinal ligament partially for anterior column release and inserted a huge cage to maximize segmental lordosis. No complications during and after the operation were observed. Further, the radiating pain and back pain improved, and the patient was discharged. Two weeks after the operation, the patient visited the outpatient department complaining of sudden recurred pain, which occurred while going to the bathroom. Radiography and computed tomography revealed a split fracture of the L5 body and an anterior cage displacement. In revision of OLIF, we removed the dislocated cage and filled the bone cement between the anterior longitudinal ligament and empty disc space. Further, we performed posterior lumbar interbody fusion L4-5, and the screw was extended to S1.Outcomes:After the second surgery, back pain and radiating pain in the left leg improved, and he was discharged without complications.Lesson:In this case, owing to insufficient intervertebral space during L4-5 OLIF, a huge cage was used to achieve sufficient segmental lordosis after anterior column release, but a vertebral body coronal fracture occurred. In patients with poor bone quality and less flexibility, a huge cage and over-distraction could cause a vertebral fracture; hence, selecting an appropriate cage or considering a posterior approach is recommended. 相似文献
94.
Background:The purpose of this study was to evaluate the clinical outcomes and complications of displaced proximal humeral fractures treated with proximal humeral internal locking system (PHILOS) plate fixation via a deltoid interfascicular (DI) vs a deltopectoral (DP) approach.Methods:This prospective case-control study was conducted with patients admitted to our hospital from May 2015 to June 2018 who suffered from unilateral displaced proximal humerus fractures. Patients were treated with PHILOS plate fixation via a DI (DI group) or DP approach (DP group). The clinical outcomes and complication data were collected for comparison between the 2 groups. The patients were followed up at 3, 6, and 12 months; and every 6 months thereafter. The patients’ functional recoveries were evaluated according to the normalized Constant-Murley score, range of motion of the shoulder (flexion, abduction, external/internal rotation) and disabilities of the arm, shoulder and hand score.Results:A total of 77 patients, followed for an average of 15 ± 2.2months (range, 12–21), were enrolled (36 in DI group and 41 in DP group) for final analysis. No significant differences in age, sex, affected side, fracture type, injury mechanism or time from injury to operation were found between the 2 groups (all P > .05). The incision length, intra-operative blood loss, and duration of operation in the DI group were significantly less than those in the DP group, respectively (all P < .05). The functional outcomes assessed by the normalized Constant-Murley score and range of motion of flexion and internal rotation in the DI group were superior to those in the DP group at 3 and 6months after the operation (P < .05); however, no significant differences were observed at the 12-month and subsequent follow-ups (all P > .05). There was no significant difference in the range of shoulder external rotation and abduction during the postoperative follow-ups (P > .05). At the last follow-up, the mean disabilities of the arm, shoulder, and hand score was 14.0 (6.6) points in the DI group and 14.4 (6.9) points in the DP group (P = .793). Complications occurred in 1 patient in the DI group and 8 patients in the DP group (P = .049).Conclusion:The current study demonstrates that DI approach is a safe and effective alternative for the treatment displaced proximal humerus fractures. The DI approach rather than DP approach was recommended when lateral and posterior exposure of the proximal humerus is required, especially when fixed with PHILOS plate. 相似文献
95.
96.
目的 探讨基于影像学特征对骨质疏松性椎体压缩骨折(OVCF)病人经皮椎体成形术(PVP)后的列线图模型预测术椎椎体再发骨折的价值。方法 回顾性纳入急性OVCF并行PVP后的病人93例。所有病人均行X线及MRI检查,根据椎体再发骨折诊断标准将病人分为再发骨折组(48例)和无再发骨折组(45例)。采用t检验和卡方检验比较2组间临床资料及影像特征的差异,对差异有统计学意义的指标进行多因素Logistic回归分析,获取再发骨折的独立危险因素,采用R软件建立列线图模型并绘制其校准曲线。采用受试者操作特征(ROC)曲线评估模型的预测效能,计算ROC曲线下面积(AUC)。应用校准曲线对列线图模型进行验证。结果 再发骨折组的椎体高度恢复率、延伸至终板的骨折线、椎体内裂隙(IVC)、骨水泥周围积液及骨水泥-终板未接触(NPEC)与无再发骨折组的差异均有统计学意义(均P<0.05);多因素Logistic回归分析显示延伸至终板的骨折线[优势比(OR)=3.232]、存在IVC(OR=27.117)和NPEC(OR=1.993)及较高的椎体高度恢复率(OR=2.943)为同椎体再发骨折的独立危险因素(... 相似文献
97.
目的:比较关节镜辅助复位内固定(ARIF)和切开复位内固定(ORIF)治疗胫骨平台骨折的疗效。方法:回顾性分析2016年1月至2018年8月华中科技大学附属协和医院骨科收治的75例胫骨平台骨折患者的资料。男58例,女17例;年龄20~54岁,平均47岁。左侧42例,右侧33例。骨折根据Schatzker分型:Ⅰ型23例... 相似文献
98.
99.
100.
Malnutrition in older adults impacts health status, increased mortality, and morbidity. Malnutrition may increase the development of geriatric syndromes and contribute to a higher prevalence of falls and osteoporotic fractures that lead to loss of independence and an increased rate of institutionalization. The role of malnutrition in the pathogenesis of other geriatric syndromes seems to be well established. However, the data concerning nutritional interventions are confounding. Moreover, long-term undernutrition seems to be one of the factors that strongly influences the efficacy of interventions. This review outlines the current literature on this topic, and aims to guide physicians to make proper decisions to prevent the vicious cycle of falls, fractures, and their negative outcomes in patients with malnutrition. 相似文献