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101.
Background
The effect of the changes in the femoral posterior condylar offset (PCO) on anterior–posterior (AP) translation and internal–external (IE) rotation in cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) remains unknown. The purpose of this study was to compare the kinematics in CR and PS TKA with respect to the difference in prosthetic design and PCO change through a computational simulation.Methods
We developed three-dimensional finite element models with the different PCOs of ± 1, ± 2 and ± 3?mm in the posterior direction using CR and PS TKA. We performed the simulation with different PCOs under a deep knee bend condition and evaluated the kinematics for the AP and IE in CR and PS TKA.Results
The more tibiofemoral (TF) translation in the posterior direction was found as PCO translated in posterior direction for both CR and PS TKA compared to the neutral position. However, the change of the AP translation with respect to the PCO change in CR TKA was greater than PS TKA. The more TF external rotation was found as PCO translated in the anterior direction for both CR and PS TKA compared to the neutral position. However, unlike the TF translation, the TF rotation was not influenced by the PCO change in both CR and PS TKA.Conclusion
The PCO magnitude was influenced by a postoperative change in the kinematics in CR TKA although a relatively smaller effect was observed in PS TKA. Hence, surgeons should be aware of the PCO change, especially for CR TKA. 相似文献102.
Boisgard S Moreau PE Descamps S Courtalhiac C Silbert H Moreel P Michel JL Levai JP 《Surgical and radiologic anatomy : SRA》2003,25(3-4):330-334
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.
Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
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.相似文献
103.
Michael E. Houston Robert W. Norman Elizabeth A. Froese 《European journal of applied physiology》1988,58(1-2):1-7
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. 相似文献
104.
Braakman R. Sipkema P. Westerhof N. 《Pflügers Archiv : European journal of physiology》1986,407(4):432-439
It has been reported that sodiumnitroprusside (SNP) decreases mean systemic pressure and simultaneously increases pressure pulse amplification towards the iliac periphery (Kenner and van Zwieten 1982). This unexpected finding was suggested to be due to a decrease in iliac peripheral resistance but an increase in iliac differential resistance. In order to investigate this apparent contradiction, the iliac periphery was hemodynamically isolated from the rest of the circulation and perfused with the dog's own blood by means of a pump. Perfusion pressure (P) and flow (F), femoral venous pressure (Pv), systemic pressure (Ps) and cardiac output (CO) were measured. Steady state pressure-flow relations of the isolated bed were obtained during control and during various i.v. infusion rates of SNP and adenosine (ADS) and were found to be straight (meanr=0.99). Their slope (P/F) was defined as differential resistance (Rd). Peripheral resistance (Rp) of the iliac bed was defined as Rp=(P-Pv)/F, calculated at the flow value where perfusion pressure equalled the prevailing systemic pressure. Total peripheral resistance (TPR) was defined as TPR=Ps/CO. The changes of Rd, Rp, Ps, CO and TPR with respect to control show that during low SNP infusion rates Rd and Rp were both increased while TPR was decreased. During all infusion rates of SNP CO did not change while Ps decreased. During low infusion rates of adenosine CO increased while Ps, Rd and Rp did not change and TPR decreased. During high infusion rates of ADS CO decreased again, Rd, Rp and Ps decreased, and TPR remained constant but at a decreased level.It is concluded that: (1) the suggestion of Kenner and van Zwieten is not supported, since SNP (as well as ADS) affects iliac peripheral and iliac differential resistance in a similar way; (2) SNP (as well as ADS) affects iliac peripheral resistance and total peripheral resistance in a differentiated way, and even in an opposite way during low infusion rates of SNP; (3) it is this opposite effect that explains the paradoxical observations of Kenner and van Zwieten; (4) for comparable reductions of TPR, CO is better maintained during infusion of SNP, while Ps is better maintained during infusion of ADS. 相似文献
105.
《The Knee》2021
BackgroundThe cruciate retaining lipped (CR-lipped) bearing is designed to provide more anterior-posterior (AP) stability and could be employed to resolve excessive intraoperative laxity during the cruciate retaining TKA (CR-TKA). The aim of the study was to determine whether the CR-lipped bearing in CR-TKAs with a perioperative excessive laxity allows equivalent functional results as compared to the standard CR articulation.MethodsA cohort of 111 TKAs with CR-lipped bearings was matched to a cohort of conventional CR bearings regarding age and sex. The CR-lipped bearing was used in patients with excessive knee AP laxity and the regular CR bearing was used in patients without excessive AP laxity during TKA. Various PROMs (WOMAC, KSS, SF-36) were assessed preoperatively and at 5-years postoperative in combination with revision rate and Range of Motion (ROM).ResultsPROMs did not differ significantly between both groups 5-years postoperatively. Mean ROM (flexion) 5-years postoperatively was not significantly different. The implant survivorship was 100% for both cohorts with revision for any reason as end point.ConclusionBased on these results, the CR-lipped bearing is a safe and effective solution for mild interoperatively assessed PCL laxity during CR-TKA without loss of function or decreased survivorship at 5 years. Peroperative conversion to a PS-TKA in order to obtain satisfactory functional scores might therefore not be necessary when mild PCL laxity is observed during surgery. Further research should focus on verifying this approach and longer follow-up is needed to generate data on long term survivorship.Level of evidenceLevel IV therapeutic, retrospective, cohort study. 相似文献
106.
A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel
model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure
and flow. The basic assumptions are a steadystate periodic regime and a purely elastic compliant element. By stating two conditions,
zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through
simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the
product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be
then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of
this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions
and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values
when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel
even in the case of nonlinear compliance. 相似文献
107.
Dr. B. K. van Kreel N. Cox-Reyven P. Soeters 《Medical & biological engineering & computing》1998,36(3):337-345
Multifrequency bio-electronic impedance analysis (MF BIA) measurements are taken from a heterogeneous group of patients, varying
in size between obese and slim. The measuring system uses four electrodes: two current and two potential electrodes. Three
new models are developed to calculate total body water (TBW) from the BIA data, and the resulting TBW values are compared
with TBW determined by D2O dilution. The results demonstrate that the most simple model provides the best TBW values. For individual patients, TBW
can be determined by means of bioimpedance measurement with an accuracy of 3 litres. In the most simple model (model 1), the
body is electrically represented by a cylinder, and corrections are made for the amount of fat. This is an extension of the
model used by Xitron. In the more advanced models (2 and 3), the body is represented by a cylinder for the trunk, and truncated
cones represent the arms and legs. In model 2, ΔTBW amounts to 3 litres. It is shown that the resistance of the trunk is proportional
to the square root of the length. In model 3, it is assumed that subcutaneous fat is a poor conductor if electric current.
An equation is developed that describes the partition of subcutaneous fat, and the fat layer is then removed from the cones
representing arms and legs and from the cylinder that models the trunk. 相似文献
108.
109.
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。 相似文献
110.
James W. Verbsky Mary K. Hintermeyer Pippa M. Simpson Mingen Feng Jody Barbeau Nagarjun Rao Carlyne D. Cool Luis A. Sosa-Lozano Dhiraj Baruah Erin Hammelev Alyssa Busalacchi Amy Rymaszewski Jeff Woodliff Shaoying Chen Mary Bausch-Jurken John M. Routes 《The Journal of allergy and clinical immunology》2021,147(2):704-712.e17