动力髋螺钉内固定治疗股骨粗隆部骨折滑动钉切出16例原因分析

目的探讨运用动力髋固定股骨粗骨隆间骨折,切出股骨头的原因及预防措施。方法总结自1998~2004年应用动力髋内固定173例股骨粗隆间骨折的治疗经验,对16例动力髋螺钉切出失败病例进行分类及分析。结果173例病人获得随访。其中,16例发生切出股骨头颈(9.24%),分析失败病例,钉的位置显示钉位置于颈中者6例(37.5%),偏后者10例(62.5%)。结论未能解剖复位、滑动钉位置不良、尖顶距过大、骨质疏松及不当功能锻炼,是内固定失败的重要因素。     

Skin sliding closure technique is effective for management of infected prostheses in cases of arterial reconstruction with synthetic grafts

A clinical review of 400 prosthetic arterial reconstructions, carried out in the Second Department of Surgery of Kyushu University Hospital during a period from 1965 to 1981, revealed 10 graft infections (2.5 per cent). There were two out of 120 abdominal aneurysms (1.7 per cent) and 8 out of 260 aorto-femoral occlusive diseases (3.1 per cent). The contributing factors included intraoperative contamination with duodenal juice during surgery for abdominal aneurysms ruptured into the duodenum (2 cases), minor hematoma and/or lymphorrhoea at the groin or lower abdominal wall (5 cases), wound infection (1 case), compression necrosis of the sigmoid colon by the implanted graft (1 case) or perityphlitic abscess due to a perforating appendicitis (1 case). Bacteriologic examination revealed a predominance of a variety of staphylococcus at the groin or lower abdominal wall and E. coli in the abdominal cavity. Four patients expired. Limb amputation had to be done in 2, and 4 were cured. In the management of infected graft at the groin or lower abdominal wall, we used with success a skin sliding closure technique after continuous wound lavage in 3 patients.     

推力滑动轴承结构参数的数值研究

以推力轴承扇形瓦块为研究对象,采用柱面坐标,通过对二维雷诺方程进行离散化求解,得出推力滑动轴承的无量纲压力分布,并通过数值计算研究方法,详细研究了瓦高比、长宽比和瓦块数对轴承润滑性能的影响规律,指出了推力滑动轴承最佳结构参数的确定方法,为推力滑动轴承的结构设计提供了理论支撑。     

鼻咽癌动态和静态调强方式的剂量学比较

目的：探讨鼻咽癌动态调强方式（Sliding window）和静态调强方式（Step and shoot）2种调强方式的剂量学差异.方法：采用CADPLAN 6.4.7（helios） 治疗计划系统,对15例鼻咽癌需调强治疗的患者用Sliding window和Step and shoot 2种调强方式4种强度水平（Intensity Level）进行剂量学差异的比较.按强度水平分为SW、SSL10、SSL7、SSL5组.对4组的剂量学评估参数：PTV最大剂量（PTVDmax）、PTV平均剂量（PTVDmean）、PTV最小剂量（PTVDmin）、剂量体积直方图（DVH） 、适型指数（Conformity index,CI）、剂量不均匀性指数（Heterogeneity Index ,HI）、机器跳数（MU） 、子野数目（Segment）等数据进行评价.结果：（1）SW组PTV Dmax与SSL10、SSL7、SSL5组间比较差异有统计学意义（P＜0.05）,而SSL10、SSL7、SSL5组比较差异无统计学意义（P＞0.05）,随着强度水平的降低,最大剂量增高;（2）SW组MU与 SSL10、SSL7、SSL5组比较差异有统计学意义（P＜0.01）,而SSL10、SSL7、SSL5组间差异无统计学意义（P＞0.05）;（3）各组间Segment差异均有统计学意义（P＜0.01）;（4）各组间CI比较差异均无统计学意义（P＞0.05）;（5）各组间HI比较差异均无统计学意义（P＞0.05）.结论：鼻咽癌不同调强方式和强度水平的治疗计划均能为临床提供较满意的剂量学分布,Sliding window方式略优于不同强度水平的Step and shoot方式,但MU和Segment较多.     

Three-dimensional finite element analysis of the mechanical stress on root from orthodontic tooth movement by sliding mechanics

Summary In order to study mechanical stress on root from orthodontic tooth movement by sliding mechanics, a 3-dimensional finite element model incorporating all layers of a human mandibular dental arch with orthodontic appliance has been developed to simulate mechanical stress on root from the orthodontic tooth movement. Simulated orthodontic force of 2 N at 0, 30 and 45 degree from the horizontal axis was applied to the crown of the teeth. The finite element analysis showed when orthodontic forces were applied to the tooth, the stress was mainly concentrated at the neck of the tooth decreasing uniformly to the apex and crown. The highest stress on the root was 0.621 N/mm² for cervical margin of the canine, and 0.114 N/mm² for apical region of the canine. The top of canine crown showed the largest amount of displacement (2.417 μm), while the lowest amount of displacement was located at the apical region of canine (0.043 μm). In conclusion, this model might enable one to simulate orthodontic tooth movements clinically. Sliding force at 2 N is ideal to ensure the bodily orthodontic tooth movement. The highest stress concentration in the roots was always localized at the cervical margin when orthodontic force of 2 N at 0, 30 and 45 degree from the horizontal axis, so there may be the same risk of root resorption when orthodontic force of 2 N at 0, 30 and 45 degree was used in clinic cases.     

Tying a loop-to-strand suture: is it safe?

OBJECTIVE: This study was undertaken to evaluate the integrity of the loop-to-strand knot when tied with square and nonidentical sliding knots. STUDY DESIGN: The synthetic absorbable monofilament suture poliglecaprone 25 in 0 and 2-0 suture gauges was used in this experiment. For each suture gauge, 3 groups of knots were tested: (1) single strand-to-single strand, flat square knot, (2) loop-to-single strand, flat square knot, and (3) loop-to-single strand, nonidentical sliding knot. All knots were tied with 6 throws. The proportion of knots becoming untied was compared among the 3 groups for each suture gauge. Ultimate load required to untie or break knots within each group was also evaluated. RESULTS: The loop-to-strand knot performed well in both suture gauges tested as long as it was tied with a flat square knot. The loop-to-strand knot tied with a nonidentical sliding knot had an unacceptably high failure rate. CONCLUSION: The loop-to-strand termination of a continuous suture may be acceptable when tied with a 6-throw flat square knot but not acceptable if tied with sliding knots.     

The effect of number of throws on knot security with nonidentical sliding knots

OBJECTIVE: The study was undertaken to test the integrity of nonidentical sliding knots made with 3 throws compared with those made with 6 throws with monofilament and braided absorbable suture. STUDY DESIGN: The 3 throw nonidentical sliding knot was compared with the 6 throw nonidentical sliding knot in 4 different suture groups. The groups were 0-0 polydioxanone, 2-0 polydioxanone, 0-0 polyglactin 910, and 2-0 polyglactin 910. Knots were tested to failure with a tensiometer. The proportion of 3 throw knots becoming untied was compared with the 6 throw knot within each group. Ultimate load required to break tied knots within each suture group was also evaluated. RESULTS: The 3 throw knots had very high rates of knot failure and untied significantly more often than the 6 throw knots. CONCLUSION: The 6 throw nonidentical sliding knot demonstrates superior knot integrity compared with the 3 throw knot with both monofilament and braided absorbable suture.     

Easyloop knot: a simple and safe extracorporeal knot

Thorough knowledge of laparoscopic suturing is of great importance to the laparoscopic surgeon, especially during the performance of advanced laparoscopic procedures. Intracorporeal and extracorporeal knot tying enhances the technical capabilities of the laparoscopic access, thus extending the spectrum of laparoscopic procedures to that of open surgery. We describe herein a new extracorporeal knot designed with an emphasis on simplicity and safety.     

Sliding multislice MRI for abdominal staging of patients with pelvic malignancies: a pilot study

PURPOSE: To integrate SMS (sliding multislice imaging technique for acquiring axial images during continuous table motion) into a high-resolution pelvic MRI protocol for additional staging of the entire abdomen within one examination. MATERIALS AND METHODS: Axial two-dimensional images were acquired during continuous table motion using a fat-saturated contrast-enhanced T1-weighted gradient echo sequence. Patients held their breath during the first 20 s of the examination and breathed normally afterward while data acquisition continued. Measurement parameters were adjusted to optimize image quality throughout the total field of view. The method was investigated in 22 patients with pelvic malignancies. Two readers independently compared SMS image quality to conventional abdominal MR images, generated by a stationary multi-breath-hold gradient echo sequence. RESULTS: Qualitative evaluation yielded high diagnostic value of SMS data in body regions with no or minor breathing motion, and in those acquired during the initial breath-hold. Image quality in the upper abdomen, retroperitoneum, and pelvis is reproducible and equivalent to stationary MRI. Interfering artifacts are related to the intestine in the mid-abdomen. CONCLUSION: SMS is a promising technique that may have the potential for a first-line abdominal staging tool in patients with pelvic malignancies.     

Design of robust‐optimal controllers with low trajectory sensitivity for uncertain Takagi–Sugeno fuzzy model systems using differential evolution algorithm

By integrating the robust stabilizability condition, the orthogonal‐function approach (OFA) and the Taguchi‐sliding‐based differential evolution algorithm (TSBDEA), an integrative computational approach is presented in this paper to design the robust‐optimal fuzzy parallel‐distributed‐compensation (PDC) controller with low trajectory sensitivity such that (i) the Takagi–Sugeno (TS) fuzzy model system with parametric uncertainties can be robustly stabilized, and (ii) a quadratic finite‐horizon integral performance index for the nominal TS fuzzy model system can be minimized. In this paper, the robust stabilizability condition is proposed in terms of linear matrix inequalities (LMIs). Based on the OFA, an algebraic algorithm only involving the algebraic computation is derived for solving the nominal TS fuzzy feedback dynamic equations. By using the OFA and the LMI‐based robust stabilizability condition, the robust‐optimal fuzzy PDC control problem for the uncertain TS fuzzy dynamic systems is transformed into a static constrained‐optimization problem represented by the algebraic equations with constraint of LMI‐based robust stabilizability condition; thus, greatly simplifying the robust‐optimal PDC control design problem. Then, for the static constrained‐optimization problem, the TSBDEA has been employed to find the robust‐optimal PDC controllers with low trajectory sensitivity of the uncertain TS fuzzy model systems. A design example is given to demonstrate the applicability of the proposed new integrative approach. Copyright © 2011 John Wiley & Sons, Ltd.