Computed tomographic study of the posterior condylar angle in arthritic knees: its use in the rotational positioning of the femoral implant of total knee prostheses

The epicondylar axis is a reliable reference to check the rotation of the femoral implant in total knee prostheses (TKPs). However, during the operation it seems easier to use the posterior condylar axis as a landmark. The angle between these two axes is called the posterior condylar angle (PCA). The aim of this study was to measure the PCA in arthritic knees to assess the reliability of the posterior condylar axis as a reference for the control of the rotation of the femoral implant and to look for correlation with other radiological measurements. This prospective study consisted of 103 arthritic knees (81 varus, 22 valgus) before a TKP had been done in 103 patients (75 women, 28 men). The assessment of the PCA was made by computed tomographic scanning (CT). The HKA, HKS and HKT angles were measured on the pangonogram. The posterior condylar axis was internally rotated with respect to the epicondylar axis. The average value for all the patients was 2.65° degrees with a range from 0° to 7°. The PCA was significantly increased in the valgus knees. There was no correlation between the angles on the pangonogram and the posterior condylar axis. While the preoperative assessment of the PCA by CT scanning is reliable, the results obtained indicate the marked variability in its value. If one wishes to use the posterior condylar axis as a guide for rotation, it is therefore necessary to assess the PCA for each patient using adjustable jigs according to the value obtained. No measurement on standard radiographs allowed an extrapolation of the value of the PCA, and CT scanning seems to be the preferable radiological examination.

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Etude tomodensitométrique de l'angle condylien postérieur dans les genoux arthrosiques. Intérêt dans le positionnement en rotation de l'implant fémoral dans les prothèses totales de genou

Résumé L'axe épicondylien est une référence fiable pour le contrôle de la rotation de l'implant fémoral dans les prothèses totales de genou (PTG). Mais, lors de l'intervention, il semble plus facile d'utiliser l'axe condylien postérieur comme repère. L'angle entre ses deux axes est appelé angle condylien postérieur (ACP). Le but de cette étude était de mesurer l'ACP dans les genoux arthrosiques, d'évaluer la fiabilité de l'axe condylien postérieur comme référence pour le réglage de la rotation de l'implant fémoral, de rechercher une corrélation avec d'autres mesures radiologiques. Une étude prospective comportant 103 genoux arthrosiques (81 varus et 22 valgus), avant PTG a été effectuée, chez 103 patients (75 femmes et 28 hommes). L'évaluation de l'ACP a été faite par examen tomodensitométrique (TDM). Les angles HKA, HKS et HKT ont été mesurés sur le pangonogramme. L'axe condylien postérieur était en rotation interne par rapport à l'axe épicondylien. La valeur moyenne pour tous les patients était de 2.65°, avec des valeurs de 0 à 7°. La valeur de l'angle CP augmentait avec une différence significative dans le groupe des genu valgum. Il n'y avait pas de corrélation entre les angles du pangonogramme et l'ACP. Si l'évaluation pré-opératoire de l'ACP par TDM est fiable, les résultats obtenus mettent en évidence une variabilité importante de sa valeur. Il faut donc, si l'on veut utiliser l'axe condylien postérieur comme repère de rotation, évaluer pour chaque patient l'ACP, et utiliser un ancillaire réglable reportant la valeur obtenue. Aucune mesure sur des radiographies standard ne permettant d'extrapoler la valeur de l'ACP, la TDM semble l'examen radiologique de choix.

     

The fourth-generation centrifugal blood pump

 The NEDO Gyro permanently implantable (PI) centrifugal blood pump has been developed as a simple, durable, centrifugal blood pump without a complex magnetic suspension system. In vitro studies were performed using a Gyro PI pump with the transparent pump housing in a mock circuit. These studies revealed that the impeller transfers to a floating or a top contact condition, which was dependent on the revolutions per minute (RPM). This pump can be easily converted from a left ventricular assist device (LVAD) to a right ventricular assist device (RVAD) by simply adding a spacer between the pump and the actuator. In order to optimize the impeller suspension for the LVAD and RVAD, spacers of the proper thickness are inserted between both of the pumps and the actuators to regulate the magnetic force. Two Gyro PI pumps were implanted in a bovine model in a 3-month biventricular assist device (BVAD) animal study. This experiment was electively terminated 90 days after implantation. All of the parameters, including pump flow rate, power consumption, and plasma free hemoglobin, were in acceptable ranges. No thrombus formation was observed in either pump. Antithrombogenesis and effectiveness were demonstrated in this animal study. The NEDO Gyro PI pump is ready to move on to the 3-month preclinical system evaluation. Received: February 28, 2002 / Accepted: May 30, 2002 Acknowledgment The New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry of Japan financially supported this project. Correspondence to:S. Ichikawa     

Local thermal sensation and finger vasoconstriction in the locally heated hand

Summary The effects of local heating on finger blood flow (BF) and local thermal sensation (Sens _w ) were studied. Finger BFs in both hands were measured simultaneously; one hand was immersed in water the temperature (T _w ) of which was raised from 35° C to 43°C by steps of 2° C every 10 min, while the other hand was kept atT _w 35°C. FingerBF in the locally heated hand decreased atT _w 37 to 41°C, while fingerBF in the control hand did not alter. Sens_w, in the heated hand showed a dynamic response, initially increasing concomitantly with an increase inT _w , then gradually returning and adapting to a new level of Sens_w. The dynamic response of Sens_w, was not perceived during mental calculation even whenT _w was raised to 40°C, and the reduction in finger blood flow was not observed. These results suggest that finger vasoconstriction caused by local heating closely relates to the dynamic response characteristic of local thermal sensation atT _w above core temperature, and that the perception of local thermal sensation in the central nervous system is involved in the mechanism of this vasoconstrictor response.     

Mechanical measures during maximal velocity knee extension exercise and their relation to fibre composition of the human vastus lateralis muscle

Summary A method for measuring the maximal velocity of knee extension exercise is described using a very light lever arm. Instrumentation of the lever arm with a potentiometer and accelerometer also allows for the measurement of peak acceleration, time to peak acceleration, the average rate of development of acceleration (jerk) and peak torque. With this apparatus and surface electromyography, electromechanical delay (EMD) was also determined. This apparatus was tested using 17 female and 10 male subjects, and the measures obtained were related to the percentage of fast twitch fibres (% FT) and the relative area of fast twitch fibres (% FTA) in the vastus lateralis determined from duplicate muscle biopsy samples. Peak velocity of unloaded knee extension averaged 12.1±1.2 and 12.2±1.7 rad · s^–1 for females and males, respectively, and were not significantly different. As well, peak acceleration, time to peak acceleration jerk and EMD values were not significantly different between the female and male subjects, but the mean peak torque for the female subjects (73.5±14.7 N · m) was significantly lower than that for the males (98.4±31.5 N · m). Peak acceleration was significantly correlated with %FT (r=0.40,P=0.04) for the total subject population. None of the other measures was significantly related to either %FT or %FTA for the male and female subjects or the combined population of subjects.     

磁场对微循环的影响

为了探讨磁场对微循环的作用，利用直径０．７ｃｍ、表面磁感强度０．３Ｔ的磁片及磁感强度０．１Ｔ、转速２５００ｒ／ｍｉｎ的旋磁机分别作用于受试者左手无名指３０ｍｉｎ，并记录作用前后微循环改变。结果表明，动、静磁场均可使微血管清晰度、血流速及管径有明显改变，而对管袢数与红细胞聚集没有影响。这一结果提示，微血管扩张、血流速加快是磁场改善微循环的基础。     

Significance of skin temperature changes in surface electromyography

Summary Differing results have been reported concerning the direction and quantity of the electromyogram (EMG) amplitude response to changes in tissue temperature. The EMG signals from the soleus muscle of six healthy human subjects were therefore recorded during dynamic exercise (concentric contractions) at ambient temperatures of 30°C and 14°C. The mean skin temperature above the muscle investigated was 32.9° C and 21.7° C, respectively. The core temperature, estimated by rectal temperature, was unchanged. The cooling of the superficial tissues caused approximately a doubling of the EMG amplitude. For the probability level 0.9 in the amplitude probability distribution function, the average signal level increased from 73 V to 135 V (P=0.02). The average mean power frequency of the EMG signal was reduced from 142 Hz to 83 Hz (P=0.004). The amplitude increase was not due to shivering but other possible explanations are presented. As the changes in T _sk investigated were within the range which may occur normally during the working hours, it was concluded that T _sk should be carefully controlled in vocational EMG studies.     

广东2003年末SARS患者冠状病毒抗原抗体动态特征分析

目的分析SARS-IgG、SARS-IgM、核壳蛋白-IgG抗体和核壳蛋白抗原的变化特点并探讨其意义。方法采用酶联免疫方法对2003年末至2004年初新发4例SARS病人的系列血清进行上述4项的滴度检测。结果在病人较早期的血清中可以检测到核壳蛋白抗原，随着抗体水平的升高，抗原含量迅速下降。抗体E升下降快，在最高水平维持时间短，并且除第1例外，其余3例的抗体滴度均小于1：100，核壳蛋白抗体变化规律与总的IgG抗体一致，但滴度更低。结论抗体变化规律与前次流行不同，抗体水平变化快，应注意及时采集标本。抗原检测可作为一种实验室诊断依据。核壳蛋白抗体可考虑用于早期诊断。     

个性化截骨工具辅助下人工全膝关节置换与传统人工全膝关节置换手术精确度及临床疗效比较

目的比较3D打印个性化截骨工具辅助(patient-specific instrumentation,PSI)下人工全膝关节置换术(total knee arthroplasty,TKA)与传统TKA的手术精确度和临床疗效。方法自2017年9月至2018年12月,将40例拟接受初次膝关节置换患者随机分为2组,每组均为20人。一组应用个性化截骨工具辅助TKA手术(PSI组),另一组接受传统TKA(对照组)。比较两组患者的冠状面下肢机械轴线、手术时间、术中出血量、术后引流量以及HSS评分。结果对照组和PSI组的手术时间分别为(103.3±18.7) min和(91.3±15.7) min;术中出血量分别为(372.0±53.0)mL和(332.8±47.0)mL;术后引流量分别为(378.8±97.2)mL和(315.0±89.0)mL。两组手术时间、术中出血量、术后引流量比较差异均有统计学意义(P0.05)。对照组和PSI组术后2周HSS评分分别为(89.3±2.8)分和(88.7±2.9)分,两组比较差异无统计学意义(P0.05)。对照组和PSI组术后全下肢力线差值分别为(1.9±1.1)°和(1.2±1.0)°,冠状面股骨假体角度(frontal femoral component angle,FFC)差值分别为(2.1±1.1)°和(1.1±0.9)°,两组比较差异有统计学意义(P0.05)。冠状面胫骨假体角度(frontal tibia component angle,FTC)差值分别为(1.3±0.8)°和(1.4±0.8)°,两组比较差异无统计学意义(P0.05)。结论PSI辅助TKA较传统TKA手术时间更短、术中出血量更少,并且术后冠状面全下肢力线及股骨力线的改善优于传统TKA手术。     

Mechanical Characterization of an In Vitro Device Designed to Quantitatively Injure Living Brain Tissue

Due to the nonlinear, viscoelastic material properties of brain, its mechanical response is dependent upon its total strain history. Therefore, a low strain rate, large strain will likely produce a tissue injury unique from that due to a high strain rate, moderate strain. Due to a lack of current understanding of specific in vivo physiological injury mechanisms, a priori assumptions cannot be made that a low strain rate injury induced by currently employed in vitro injury devices is representative of clinical, nonimpact, inertial head injuries. In the present study, an in vitro system capable of mechanically injuring cultured tissue at high strain rates was designed and characterized. The design of the device was based upon existing systems in which a clamped membrane, on which cells have been cultured, is deformed. However, the present system incorporates three substantial improvements: (1) noncontact measurement of the membrane deflection during injury; (2) precise and independent control over several characteristics of the deflection; and (3) generation of mechanical insults over a wide range of strains (up to 0.65) and strain rates (up to 15s^–1). Such a system will be valuable in the elucidation of the mechanisms of mechanical trauma and determination of injury tolerance criteria on a cellular level utilizing appropriate mechanical injury parameters.     

微机控制的韧带动态力学特性测试系统

本系统是为自动测试人体韧带或类似组织的动态力学特性试验而研制的。在试验时,受控的加载过程和数据采集过程同时进行。系统向韧带试件提供一个快速的匀速可控的拉伸载荷,模拟人体剧烈运动的实况,同时实时采集力和变形的数据。系统还提供对所采集数据的分析手段,从而得到力、变形、应力、应变、弹性模量和变形能等参数之间的关系,并可以图形和文字形式输出。系统亦可将各数据文件转换为其它应用软件包可接受的形式,以便利用标准商品软件包的数据和图象处理能力。系统采用菜单提示的人机对话方式进行监控。