膝关节三维模型的构建

通过对逆向工程技术的研究,提出了一种构建膝关节三维模型的新方法。首先,分别对已有膝关节假体原型和志愿者的股骨远端及胫骨近段进行数据的采集;其次,利用逆向工程软件Geomagic和Mimics分别对膝关节假体原型的点云数据和股骨远端和胫骨近端的CT图像进行处理,然后利用三维软件PRO/E进行再设计;最后按顺序在PRO/E软件中装配成膝关节三维模型。模型的建立为进一步进行膝关节生物力学分析提供了方法与平台,同时也为人工膝关节模型数据库的建立提供了方法。     

晚期弥漫型色素沉着绒毛结节性滑膜炎行全膝关节置换的初步探讨

目的:探讨晚期弥漫型色素沉着绒毛结节性滑膜炎(Pigmented Villonodular Synovitis,PVNS)行全膝关节置换治疗(Total knee arthroplasty,TKA)及其临床疗效。方法:对2003年2月至2010年10月年收治的16例发生于单侧膝关节(左膝11例,右膝5例)的弥漫型PVNS行滑膜切除术后的TKA。其中男性5例,女性11例,年龄37至66岁,平均57.2岁;4名患者有膝关节外伤史及1至2次患侧膝关节手术史,余病例发病前均无明显诱因;术前平均屈伸活动度为:屈:101°(75°至120°)、伸:-6°(-10°至0°);HSS评分:59.2±7.3。结果:1例患者出现了下肢深静脉血栓、1例患者术后功能恢复较差,余病例均取得较满意的功能恢复。末次随访平均活动度:屈:125°(95°至130°)、伸:-1°(-5°至0°),HSS评分:85.3±8.1,与术前相比有统计学意义(P0.05)。术后随访21至83个月,平均47个月,均未见PVNS复发及假体松动。结论:MRI在该疾病诊断、明确病变范围、术后评估各方面起着重要的作用。对于软骨破坏严重的晚期弥漫型PVNS,TKA应作为首选治疗,但相比其他疾病的TKA治疗,术中需注意更多细节的处理。而术后至抗凝药物应用的间隔时间是否应适度延长、术后是否需应用局部放射治疗仍有待进一步研究。     

A position based kinematic method for the analysis of human gait

Human joint motion can be kinematically described in three planes, typically the frontal, sagittal, and transverse, and related to experimentally measured data. The selection of reference systems is a prerequisite for accurate kinematic analysis and resulting development of the equations of motion. Moreover, the development of analysis techniques for the minimization of errors, due to skin movement or body deformation, during experiments involving human locomotion is a critically important step, without which accurate results in this type of experiment are an impossibility. The traditional kinematic analysis method is the Angular-based method (ABM), which utilizes the Euler angle or the Bryant angle. However, this analysis method tends to increase cumulative errors due to skin movement. Therefore, the objective of this study was to propose a new kinematic analysis method, Position-based method (PBM), which directly applies position displacement data to represent locomotion. The PBM presented here was designed to minimize cumulative errors via considerations of angle changes and translational motion between markers occurring due to skin movements. In order to verify the efficacy and accuracy of the developed PBM, the mean value of joint dislocation at the knee during one gait cycle and the pattern of three dimensional translation motion of the tibiofemoral joint at the knee, in both flexion and extension, were accessed via ABM and via new method, PBM, with a Local Reference system (LRS) and Segmental Reference system (SRS), and then the data were compared between the two techniques. Our results indicate that the proposed PBM resulted in improved accuracy in terms of motion analysis, as compared to ABM, with the LRS and SRS.     

P级电流互感器抗饱和能力校核方法探讨

介绍了目前校核P级电流互感器抗饱和能力的方法,通过论证和实例计算,分析拐点电势法的问题和不足,指出复合误差法更加科学、准确。     

钢结构中V形支撑的抗震性能影响因素的定量分析

事实上,根据设计和荷载规范进行抗震设计时,需要确定地震反应修正系数R、高强度系数Ω0和变形放大系数Cd。针对结构的横向支撑系统,也即V形支撑(CKB)对上述系数进行评估。这类支撑系统中的V形构件在支撑系统内形成弯曲或剪切塑性铰,有助于系统的能量耗散。采用基于低概率结构倒塌的FEMAP695方法进行研究,包含非线性静动力学分析。通过静力弹塑性分析研究这种支撑的高强度和延性。通过增量动力分析(IDA)获得原始模型的抗倒塌储备系数(CMRs),并对其进行修改,得到每个原始模型调整后的抗倒塌储备系数(ACMR)。计算得到的ACMRs满足考虑了整体系统倒塌的不确定性的FEMAP695的要求,证明了CKB系统假定的抗震性能影响因素的有效性。     

Regenerative Engineering for Knee Osteoarthritis Treatment: Biomaterials and Cell-Based Technologies

Knee osteoarthritis (OA) is the most common form of arthritis worldwide. The incidence of this disease is rising and its treatment poses an economic burden. Two early targets of knee OA treatment include the predominant symptom of pain, and cartilage damage in the knee joint. Current treatments have been beneficial in treating the disease but none is as effective as total knee arthroplasty (TKA). However, while TKA is an end-stage solution of the disease, it is an invasive and expensive procedure. Therefore, innovative regenerative engineering strategies should be established as these could defer or annul the need for a TKA. Several biomaterial and cell-based therapies are currently in development and have shown early promise in both preclinical and clinical studies. The use of advanced biomaterials and stem cells independently or in conjunction to treat knee OA could potentially reduce pain and regenerate focal articular cartilage damage. In this review, we discuss the pathogenesis of pain and cartilage damage in knee OA and explore novel treatment options currently being studied, along with some of their limitations.     

膝关节矢状面接触分析的研究

软骨给膝关节提供了一种摩擦系数比最好的人工材料要低许多倍的低摩擦抗磨损的支撑面,而且会减小下面胫骨的接触应力.为了了解和比较软骨在正常情况下和病理状态下的相关生物力学机理,建立了矢状面上包含胫股和膑股关节的膝关节二维有限元接触模型,认为模型所有组成部件都为弹性体,运用有限元方法求解了膝关节屈曲过程中矢状面上股骨与胫骨接触过程中有无覆盖软骨层对应力及接触面积的变化.结果表明由于自然关节覆盖着软骨层,在屈膝过程中增大了股胫关节的接触线,减小了股骨屈膝所需要的力矩和胫骨应力.从力学角度解释了膝关节软骨对膝关节的保护作用,从而更加真实地描述了膝关节的力学接触机制.     

Accurate work-rate measurements during in vivo MRS studies of exercising human quadriceps

INTRODUCTION: Given that we have reached a point in the field of muscle energetics where absolute measurements are warranted to take the area forward, we designed an ergometer, including two force and two displacement transducers, allowing dynamic and isometric knee extension within a MR system and accurate measurements of power output. METHODS: On the basis of repeated measurements, the force and displacement transducers accuracy was 1% for values ranging from 0 to 394 N and 4% for values ranging from 0 to 20 cm. In addition, measurements were not affected by magnetic field. MRS experiments in exercising muscle were conducted in eight subjects. They performed two standardized dynamic alternate leg extension exercises (25 and 35% of MVC) while the corresponding metabolic changes were measured using (31)P-MRS. RESULTS: The mean power output produced during both exercises were 63 +/- 16 and 81 +/- 15 W while the eccentric work was reduced i.e. 12 +/- 14 and 21 +/- 6 W for the moderate and heavy exercise respectively. The corresponding metabolic changes were significant with a 20-40% PCr depletion and an end of exercise pH ranging from 0.02 to 0.70 pH units. CONCLUSION: Overall, the present ergometer allows quadriceps exercise in a MR system and should be useful for future metabolic studies for which reliable and absolute quantification of power output is warranted.     

Tribological testing of articular cartilage of the medial compartment of the knee using a friction simulator

The aim of this study was to develop a tribological simulation of a unicondylar natural knee, to measure the friction and wear of articular cartilage (AC) against itself (AC-vs-AC) and against stainless steel (SS) simulating a hemiarthroplasty (AC-vs-SS). AC-vs-AC produced low levels of friction and no wear was found. AC-vs-SS showed higher levels of friction and significant AC wear. Using AC-vs-SS with elevated loading, the wear of AC was accelerated and through to bone. This study demonstrated the importance of contact stress in the design of a spacer hemiarthroplasty for the medial compartmental knee. Initial results showed the importance of contact mechanics, stress and biomaterial type in determining short-term tribological function and long-term clinical outcome of hemiarthroplasty.     

Workload of window cleaners using ladders differing in rung separation

The objective of the present study was to compare energetic workload, perceived exertion, perceived discomfort, safety, and mechanical load at lower limb joints among window cleaners during usage of extension ladders with 30 and 35 cm rung separation. Eleven healthy male professional window cleaners of short and tall stature participated in this study. No significant differences between 30 and 35 cm rung separation were observed for the energetic workload. Results concerning the perceived exertion, discomfort, and safety indicate that 35 cm rung separation is preferred. Based on the mechanical load at the hip, knee, and ankle during ascending and descending the ladder, 30 cm rung separation is preferable to 35 cm rung separation. It is advised to climb ladders with the knees inside the side rails of the ladder, but this seems only possible with 35 cm rung separation. Findings of the presents study suggest that overall, a 35 cm rung separation is marginally favourable while using extension ladders.