The injury of the knee joint is usually accompanied with the generation of hydrops. The volume of hydrops can be used as a reference to evaluate the extent of knee joint injuries. Based on the principle of bioimpedance detection, in this paper, a new method is proposed to detect knee joint hydrops. Firstly, a three-dimensional model of the knee joint was established according to the physiological and anatomical structure of the knee joint. Secondly, a knee impedance detection system was constructed based on the four-electrode theory, and the relationship between the knee impedance change and the volume of hydrops was calculated by linear regression. Finally, the model of rat knee joint hydrops was established, and the knee joint impedance was measured under different hydrops content to deduce the relationship between the fluid content and the knee joint impedance. The fluid volume in the joint was calculated by measuring the knee joint impedance, and the error rate was less than 10%. The experimental results show that the method proposed in this paper can establish the relationship between the impedance of the knee and the volume of fluid and realize the detection of the fluid volume.
膝关节的损伤往往伴随着积液的产生，积液含量的多少通常可以作为膝关节损伤程度的判定标准之一。本文基于生物阻抗检测原理，提出了一种新型膝关节积液检测方法。首先根据膝关节生理解剖结构建立三维膝关节模型，改变三维模型中积液部分的体积来模拟膝关节损伤程度的变化过程。其次，基于四电极理论搭建膝关节阻抗检测系统，利用线性回归计算出膝关节阻抗与膝关节积液含量之间的关系。最后，制作大鼠膝关节积液模型，改变其膝关节内的液体含量，测量不同积液含量下的膝关节阻抗，推导出积液含量与膝关节阻抗之间的关系式，通过测量膝关节阻抗计算出关节内的液体含量，计算误差率低于10%。实验结果表明，本文提出的膝关节阻抗检测方法可反映膝关节阻抗和积液量之间的关系，可以实现膝关节积液含量的测量。.
Keywords: bioimpedance; four-electrode measuring; hydrops of the knee joint.