Study On Biological Impedance Simulation And Detection Method Of Knee Effusion

In the numerous joints of the human body,the largest area,the most complex structure,bear the most weight of the joint is the knee joint.The injury of knee joint often accompanies the generation of effusion.The amount of effusion can be used as one of the criteria for the degree of knee joint injury.In clinical tests,nuclear magnetic resonance(NMR),ultrasound and subjective floating patellar test are the most frequently used methods for detecting knee joint effusion.These methods are expensive or highly subjective,and cannot form objective test reports.In this paper,a new method for detecting the content of knee joint effusion is proposed based on the four-electrode bioimpedance detection method.Firstly,according to the physiological anatomical structure of the knee joint and various common knee joint injuries,the physiological characteristics of the knee joint in the state of pathogenesis and the changes of electrophysiological signals,a three-dimensional simulation model of the knee joint was established and a simulation system was established.By changing the fluid part of the 3 d model of the size and the material conductivity to simulate the knee joint in the amount of fluid in the process of change,has damage on knee joint damage status,but not with hematoma and damage and with hematoma state simulation study on three kinds of model,according to the results of the simulation calculation analysis of the knee joint electrical impedance with the change of fluid,namely when inside the knee joint effusion content increased,the knee joint of biological impedance are obviously reduced.Secondly,based on the bioelectric impedance measurement technology,a set of knee joint impedance measurement system is designed and built.In order to avoid the damage caused by simulated knee joint effusion to human body,this paper designed and made a knee joint AGAR model according to the physiological anatomical structure of the knee joint and the electrical conductivity distribution of human tissue structure.Normal saline of different volumes was injected into the articular cavity of the AGAR model to simulate the process of fluid accumulation.The quantitative relationship between the content of knee joint effusion and the biological impedance of knee joint was obtained by measuring the electrical impedance of the AGAR model with the established knee joint impedance measurement system.Then,Nacl solution with different conductivity was prepared and injected into the articular cavity of the AGAR model to simulate the pathological process of knee joint bleeding.Biological impedance of knee joint under different blood bleeding conditions was measured to fit the relationship between the content of knee joint effusion,the conductivity of knee joint effusion and the impedance of knee joint.Then,the rats were selected for the hydrops measurement experiment,and the basic impedance of the knee was measured by the knee joint impedance measurement system.Normal saline was injected into the knee joint of the rats to force the change of the liquid content in the knee joint,and the hydrops model of the knee joint of the rats was made.The knee impedance of the rats was measured every time the saline was injected.Finally,the linear regression method was used to fit the relationship between knee joint effusion and knee joint impedance in the rat experiment,and its feasibility was verified.The results showed that in organisms,the change of knee joint effusion content would cause the change of knee joint impedance,and the change of knee joint effusion content could be reflected by the impedance measurement of knee joint,and there was a certain quantitative relationship between the two.Experimental results show that the proposed method based on four electrodes can detect the content of knee joint effusion and provide help for the detection and treatment of knee joint effusion.