Modified sliding trochanteric osteotomy in revision total hip arthroplasty

Traditional trochanteric sliding osteotomy preserves the lateral aspect of the greater trochanter, the abductors, and vastus lateralis in continuity. Our modification uses a lateral approach to the hip and osteotomy immediately anterior to the insertion of the posterior capsule and external rotators onto the greater trochanter. The osteotomy and attached abductors and vastus lateralis are translated anteriorly, leaving the posterior capsule and external rotators attached to the proximal femur. This surgical approach preserves the posterior soft-tissue stabilizing structures that resist posterior dislocation of the hip. In a retrospective review of 2 consecutive 2-year series of acetabular component revisions only between 1997 and 2001, 4 of 27 acetabular revisions using a traditional trochanteric slide subsequently dislocated; only 1 of 30 subsequent cases using a modified sliding trochanteric osteotomy dislocated. Modified sliding trochanteric osteotomy facilitated surgical exposure and produced a trend toward a lower dislocation rate that did not reach statistical significance with the small numbers of patients available.     

Effects of a sliding plate on morphology of the epiphyseal plate in goat distal femur

The aim of this study was to observe the effects of a sliding plate on the morphology of the epiphyseal plate in goat distal femur. Eighteen premature female goats were divided randomly into sliding plate, regular plate and control groups. Radiographic analysis and histological staining were performed to evaluate the development of epiphyseal plate at 4 and 8 weeks after surgery. In the sliding plate group, the plate extended accordingly as the epiphyseal plate grows, and the epiphyseal morphology was kept essential normal. However, the phenomenon of the epiphyseal growth retardation and premature closure were very common in the regular plate group. In addition, the sliding plate group exhibited more normal histologic features and Safranin O staining compared to the regular plate group. Our results suggest that the sliding plate can provide reliable internal fixation of epiphyseal fracture without inhibiting epiphyseal growth.     

Identifying clinically relevant sliding hiatal hernias: a population-based endoscopy study

Objectives: The clinical relevance of small to moderate sliding hiatal hernias is controversial. The aims of the present study were to (1) investigate which symptoms are associated with sliding hiatal hernias and (2) define the length of a sliding hiatal hernia at which gastrointestinal symptoms occur.

Methods: A study population representative of the general Swedish population answered a questionnaire regarding gastrointestinal symptoms and was investigated with an upper endoscopy. The length of any sliding hiatal hernia was measured.

Results: Only reflux-related symptoms were associated with length of the hiatal hernia (acid regurgitation OR 1.46, CI 1.19–1.79, heartburn OR 1.27, CI 1.05–1.54), and the association did not become significant until an axial hiatal hernia length of 2?cm.

Conclusions: Only reflux symptoms could be attributed to sliding hiatal hernias. Hiatal hernias less than 2?cm should be considered clinically insignificant.     

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目的探讨改良直丝弓一步滑动法关闭拔牙间隙的临床疗效。方法选择2006年7月至2008年1月到广西梧州市红十字会医院口腔科就诊的安氏I类双颌前突患者共20例,按就诊顺序将患者牙弓的4个区左右配对随机分组,单数患者牙弓的左上区和左下区为试验组,右上区和右下区为对照组;双数患者分组与之相反。试验组采用颊侧镍钛丝拉簧加舌侧弹性牵引关闭间隙,对照组采用颊侧镍钛丝拉簧牵引关闭间隙。测量间隙关闭量后进行统计学分析。结果试验组间隙关闭速度为每月(0.98±0.03)mm,对照组为每月(0.79±0.03)mm,两组间比较差异有统计学意义(P<0.01);两组尖牙牙根和牙槽骨治疗前后变化比较差异均无统计学意义。结论应用改良直丝弓一步滑动法关闭拔牙间隙,速度快,费用少、临床疗效良好,具有很好的推广应用前景。     

Factors influencing efficiency of sliding mechanics to close extraction space: a systematic review

OBJECTIVES: To review recent literature to determine strength of clinical evidence concerning the influence of various factors on the efficiency (rate of tooth movement) of closing extraction spaces using sliding mechanics. DESIGN: A comprehensive systematic review on prospective clinical trials. An electronic search (1966-2006) of several databases limiting the searches to English and using several keywords was performed. Also a hand search of five key journals specifically searching for prospective clinical trials relevant to orthodontic space closure using sliding mechanics was completed. Outcome Measure - Rate of tooth movement. RESULTS: Ten prospective clinical trials comparing rates of closure under different variables and focusing only on sliding mechanics were selected for review. Of these ten trials on rate of closure, two compared arch wire variables, seven compared material variables used to apply force, and one examined bracket variables. Other articles which were not prospective clinical trials on sliding mechanics, but containing relevant information were examined and included as background information. CONCLUSION - The results of clinical research support laboratory results that nickel-titanium coil springs produce a more consistent force and a faster rate of closure when compared with active ligatures as a method of force delivery to close extraction space along a continuous arch wire; however, elastomeric chain produces similar rates of closure when compared with nickel-titanium springs. Clinical and laboratory research suggest little advantage of 200 g nickel-titanium springs over 150 g springs. More clinical research is needed in this area.     

Improved gradient-echo 3D magnetic resonance imaging using pseudo-echoes created by frequency-swept pulses.

Frequency-swept pulses are not typically employed to excite spins in NMR. When used for selective excitation in MRI, such pulses do not produce a proper echo because the phase of the transverse magnetization varies in a quadratic manner across the slice or slab. Previously, frequency-swept pulses such as the chirp pulse have been shown to offer an approach to reduce the peak radiofrequency power required for excitation. It has also been shown that chirp excitation produces a unique type of echo (dubbed "pseudo-echo" here) and images can be generated from the resultant pseudo-echoes using a quadratic reconstruction method (J.G. Pipe, Magn Reson Med 1995;33:24-33). The present work describes a general theory and methods for exciting spins with other types of frequency-swept pulses (HSn pulses), which offer the advantage of delivering better excitation profiles than the chirp pulse. Here, pseudo-echoes are produced with HSn pulses in conventional gradient-echo 3D MRI, and high-quality images are reconstructed using standard fast Fourier transformation. An optional apodization procedure using a sliding window function is also introduced. When the dynamic range of the analog-to-digital converter is limiting, signal-to-noise ratio of pseudo-echo imaging is superior to that obtained with standard excitations.     

Design of sliding mode control for neutral delay systems with perturbation in control channels

This paper considers the problem of sliding mode control for a class of uncertain neutral delay systems. There are uncertainties not only in the state matrices, but also in the control matrix that results from perturbation in the control channels. By means of a sliding surface dependent on both the current states and delayed states, a sliding mode controller is designed such that the asymptotic stability of closed‐loop systems can be ensured. The design of both the sliding surface and the sliding mode controller can be obtained via convex optimization. It is shown that the state trajectories are driven onto the specified sliding surface in finite time and remain there for subsequent time. Finally, a numerical simulation example is provided. Copyright © 2011 John Wiley & Sons, Ltd.     

The rationale,evolution and clinical application of the self-ligating bracket

There is ample evidence in the literature that conventional orthodontic mechanics while intended to move teeth efficiently rarely achieve atraumatic remodeling of periodontal tissues. The vascular supply is often interrupted, which in turn affects the oxidative metabolism. Moreover, teeth splinted in groups do not appear to move as efficiently as single teeth. The novel bracket design and treatment regimen described in this report allow teeth to move individually, yet stay within a group. The self-ligating bracket design allows for rapid leveling because teeth drift along the path of least resistance with little or no friction between the bracket and slot of the wire. The hinge mechanism eliminates much of the friction created by the conventional wire or latex ties used to secure the archwire in the bracket slot. Thus, sliding mechanics is achieved in the true sense of the word. This system is capable of increasing the appointment intervals, and possibly reducing the overall treatment time.     

考虑弹性变形的不同综合曲率下的滑动副油膜计算

本文介绍了考虑滑动副中较软元件弹性变形及贫油状态的滑动副承载能力计算,其中变形计算采用了半无限体法,并参照联邦德国Bernd Schaude著作采用了简化的处理方法,大大简化了计算过程,且便于利用油压分布计算中的差分格式。为了保证计算精度,减少计算时间,采用了合理划分网格,合理选定计算顺序和设法加速收敛等措施。     

Transport distraction osteogenesis following marginal resection of the mandible

We performed sliding transport distraction osteogenesis (STDO) of an alveolar segment containing an unerupted third molar in the mandible of a 22-year-old man with a benign cementoblastoma. Marginal mandibulectomy including the tumour and the right mandibular second premolar and first and second molars was done. STDO was performed to horizontally reconstruct the alveolar ridge and to restore occlusion with the use of the third molar. After forward horizontal distraction of the alveolar segment, the third molar spontaneously erupted and was gradually moved to the position previously occupied by the second molar.