等长伸膝动作的运动单元放电特征分析

本研究基于表面肌电分解技术,分析伸膝动作中不同发力状态下大腿肌肉运动单元的解码准确性,并对比神经特征和肌电特征在肌肉激活程度估计中的效果. 12名大学生分别以2种发力速度和4种发力等级完成伸膝动作的等长收缩.实验同步采集受试者股内侧肌和股外侧肌处的高密度表面肌电信号和伸膝动作收缩力.基于卷积核补偿算法解码肌电信号得到运动单元动作电位,提取神经特征用于收缩力的互相关分析.结果发现,对于股内侧肌,2种任务及4种收缩力等级下平均解码得到(7±4)个运动单元,股外侧肌平均解码得到(9±5)个运动单元.它们的平均脉冲信噪比(pulse-to-noise ratio,PNR)为30.1 d B,对应解码准确率大于90%.股内侧肌的两种神经特征与力之间的平均相关性分别为(0.79±0.08)和(0.80±0.08),股外侧肌的两种神经特征与力之间的平均相关性分别为(0.85±0.05)和(0.85±0.06).综上可见,基于肌电分解技术可以准确识别不同发力状态下大腿肌肉的运动单元放电活动,并且运动单元放电频率与伸膝动作力高度相关,研究结果可用于运动康复、运动训练及人机接口等领域.     

Evaluation of the mechanical efficiency of knee braces based on computational modeling

Knee orthotic devices are commonly prescribed by physicians and medical practitioners for preventive or therapeutic purposes on account of their claimed effect: joint stabilisation and proprioceptive input. However, the force transfer mechanisms of these devices and their level of action remain controversial. The objectives of this work are to characterise the mechanical performance of conventional knee braces regarding their anti-drawer effect using a finite element model of a braced lower limb. A design of experiment approach was used to quantify meaningful mechanical parameters related to the efficiency and discomfort tolerance of braces. Results show that the best tradeoff between efficiency and discomfort tolerance is obtained by adjusting the brace length or the strap tightening. Thanks to this computational analysis, novel brace designs can be evaluated for an optimal mechanical efficiency and a better compliance of the patient with the treatment.     

An informational framework to predict reaction of constraints using a reciprocally connected knee model

Researchers have used screw theory to describe the motion of the knee in terms of instantaneous axes of the knee (IAK). However, how geometric change to the dynamic alignment of IAK may affect stance phase of foot loading has not yet been fully explained. We have tested our informational framework through readily accessible benchmark data (Fregly et al. 2012): muscle contraction and ground reaction force are compounded into a wrench that is reciprocal to the IAK and resolved into component wrenches belonging to the reciprocal screw system. This revealed the special screw system that defines the freedom available to the knee and more precisely revealed how to measure this first order of freedom. After this step, we determined the reciprocal screw system, which involves the theory of equilibrium. Hence, a screw system of the first order will have a screw system of the fifth order as its reciprocal. We established a framework the estimation of reaction of constraints about the knee using a process that is simplified by the judicious generation of IAK for the first order of freedom in equilibrium.     

The development,calibration and validation of a numerical total knee replacement kinematics simulator considering laxity and unconstrained flexion motions

Kinematics testing is essential during the development of total knee replacement (TKR) designs. Although computational analysis cannot replace physical testing, it offers repeatability and consistency at a much lower cost and shorter time, making it an excellent complement to experiments. Previous numerical models have been limited by several factors: the validity of the models is usually only considered for a single TKR design, friction models are typically overly simplified and the determination of simulation parameters is often inadequate, or tedious and expensive. The objective of this study is to develop, calibrate and validate a TKR kinematics simulation considering multiple TKR geometries, an accurate friction model and simulation parameters determined using a systematic optimisation method. The calibrated model was able to predict TKR kinematics for different TKR geometries, and is ideal for screening new implant designs, reducing the number of experiments required at the design stage.     

Reduction of knee range of motion during continuous passive motion due to misaligned hip joint centre

When using continuous passive motion (CPM) devices, appropriate setting of the device and positioning of the patient are necessary to obtain maximum range of motion (ROM). In this study, the ROMs in both the knee joint and CPM device during CPM treatment were measured using a motion analysis system for three different CPM devices. Additionally, the trajectories of the angles at the knee for hip joint misalignments were evaluated using kinematic models of the three CPM devices. The results showed that discrepancies in ROM between the knee joints and the CPM device settings during CPM treatment were revealed regardless of the CPM device and that the effect of misalignment is dependent on the design of the CPM device. The present technology could be applied for the development of a better design configuration for the CPM device to reduce the discrepancy in ROM at the knee joint.     

Knee joint biomechanics in closed-kinetic-chain exercises

Effective management of knee joint disorders demands appropriate rehabilitation programs to restore function while strengthening muscles. Excessive stresses in cartilage/menisci and forces in ligaments should be avoided to not exacerbate joint condition after an injury or reconstruction. Using a validated 3D nonlinear finite element model, detailed biomechanics of the entire joint in closed-kinetic-chain squat exercises are investigated at different flexion angles, weights in hands, femur-tibia orientations and coactivity in hamstrings. Predictions are in agreement with results of earlier studies. Estimation of small forces in cruciate ligaments advocates the use of squat exercises at all joint angles and external loads. In contrast, large contact stresses, especially at the patellofemoral joint, that approach cartilage failure threshold in compression suggest avoiding squatting at greater flexion angles, joint moments and weights in hands. Current results are helpful in comprehensive evaluation and design of effective exercise therapies and trainings with minimal risk to various components.     

人工全膝关节置换术50例临床效果观察

目的：探讨人工全膝关节置换术临床效果。方法：选择我院2008年1月至2011年1月收治的行人工全膝关节置换术的患者50例53膝,对其临床资料进行回顾性分析。并作术前、术后HSS评分比较。结果：HSS术后评分,优47膝,占88．7％,良4膝,占7．5％,一般2膝,占3．7％。类风湿性关节炎4例HSS术前评分为35．24±11．78,术后评分为89．61±10．37;骨性关节炎44例HSS术前评分为44．37±10．29,术后评分为91．47±15．65;创伤性关节炎5例HSS术前评分为39．23±11．56。术后评分为90．61±13．2。术前、术后比较差异均有统计学意义（P〈0．05）。术后整体优良率为96．2％。无严重并发症发生。结论：人工全膝关节置换术实施过程中,制订严密的手术计划,拥有高操作技术和理论基础,做好生命体征的密切观察及术后整体的康复功能训练,可取得较好疗效。     

全膝关节置换术后多模式镇痛中非选择与选择性COX-2抑制剂的对比应用研究

目的：评价全膝关节置换术后病人早期功能锻炼过程中应用选择性环氧化酶-2（COX-2）抑制剂帕瑞昔布钠与非选择性环氧化酶（COX）抑制剂氟比洛芬酯之间的镇痛效果是否存在差异,以及对早期功能锻炼结果的影响。方法：前瞻性、随机、双盲、平行对照研究,根据纳入/排除标准,连续选取2009年6月至2010年3月在我科行单侧人工全膝关节置换术的病人60名。手术均采用腰麻联合硬膜外阻滞麻醉,由同一组手术医师完成,术中假体安装前关节周围软组织注射＂鸡尾酒＂镇痛液（罗哌卡因注射液150mg＋肾上腺素（1：1000）0.5ml,由生理盐水稀释为100ml）。手术结束后进行病人自控静脉镇痛（PCIA）。术后当天患者在护士的指导下进行股四头肌收缩功能锻炼及直腿抬高功能锻炼。术后第一天起行膝关节被动伸屈功能锻炼（CPM）及主动伸屈功能锻炼。术后第3至5天患者停PCIA镇痛后,进行试验干预。帕瑞昔布钠组给予注射用帕瑞昔布钠40mg,静注1/12小时。氟比洛芬酯组给予氟比洛芬酯注射液100mg,静注1/12小时。观察病人术后第3至5天静息状态下和活动锻炼时膝关节最大主动屈曲时的疼痛强度（VAS评分）,手术侧膝关节的主动伸屈活动度及术后1月复查时的手术侧膝关节的主动伸屈活动度,KSS评分,术后第2天与第6天的血红蛋白值。结果：两组病人给药后在静息状态及膝关节最大主动屈曲时,在不同时间点的VAS评分、膝关节主动活动度及术后1月患者膝关节的主动活动度和KSS评分的差异均无统计学意义（P〉0.05）。应用抗凝治疗后,帕瑞昔布钠组患者血红蛋白下降值与氟比洛芬酯组存在差异（P=0.042）。结论：尚不能认为人工全膝关节置换术后多模式镇痛中同时抑制COX-1和COX-2与选择性抑制COX-2之间存在差异。但应用选择性COX-2抑制剂（帕瑞昔布钠）镇痛更安全,因其有利于减少全膝关节置换术后患者抗凝治疗过程中的隐性失血。     

Study on the Microstructure of Human Articular Cartilage/Bone Interface

For improving the theory of gradient microstructure of cartilage/bone interface, human distal femurs were studied. Scanning Electron Microscope (SEM), histological sections and MicroCT were used to observe, measure and model the microstructure of cartilage/bone interface. The results showed that the cartilage/bone interface is in a hierarchical structure which is composed of four different tissue layers. The interlocking of hyaline cartilage and calcified cartilage and that of calcified cartilage and subchondral bone are in the manner of “protrusion-pore” with average diameter of 17.0 μm and 34.1 μm respectively. In addition, the cancellous bone under the cartilage is also formed by four layer hierarchical structure, and the adjacent layers are connected by bone trabecula in the shape of H, I and Y, forming a complex interwoven network structure. Finally, the simplified structure model of the cartilage/bone interface was proposed according to the natural articular cartilage/bone interface. The simplified model is a 4-layer gradient biomimetic structure, which corresponds to four different tissues of natural cartilage/bone interface. The results of this work would be beneficial to the design of bionic scaffold for the tissue engineering of articular cartilage/bone.