Knee Osteoarthritis Electrical Impedance Measurements

Abstract—This study proposes a multiclass model to classify the severity of knee osteoarthritis (KOA) using bioimpedance measurements. The experimental setup considered three types of measurements using eight electrodes: global impedance with adjacent pattern, global impedance with opposite pattern, and direct impedance measurement, which were taken using an electronic device proposed by authors and based on the Analog Devices AD5933 impedance converter. The study comprised 37 participants, 25 with healthy knees and 13 with three different degrees of KOA. All participants performed 20 repetitions of each of the following five tasks: (i) sitting with the knee bent, (ii) sitting with the knee extended, (iii) sitting and performing successive extensions and flexions of the knee, (iv) standing, and (v) walking. Data from the 15 experimental setups (3 types of measurements × 5 exercises) were used to train a multiclass random forest. The training and validation cycle was repeated 100 times using random sampling. At each of the 100 cycles, 80% of the data were used for training and the rest for testing. The results showed that the proposed approach achieved average sensitivities and specificities of 100% for the four classes in the extension, cyclic, and gait tasks. This suggests that the proposed method can serve as a screening tool to determine which individuals should undergo X-rays or magnetic resonance imaging for further evaluation of KOA. Bioimpedance measurements (BIM) were conducted using a custom-designed eight-channel electronic prototype previously developed. The BIM system incorporates an AD5933 impedance converter, which generates a 50 kHz alternating voltage signal. This signal is then converted intoa 1 mA alternating current using a voltage-controlled current source. Two sets of 74HC4067 multiplexers are utilized, with one pair selecting the electrodes for current injection, and the other pair selecting the electrodes for voltage measurement. The electrodes were placed in the frontal plane around the knee and forming a circle.The bioimpedance measurement system is described in this link: https://doi.org/10.1016/j.ohx.2022.e00274

摘要——本研究提出了一种多分类模型，旨在利用生物阻抗测量技术对膝关节骨关节炎（KOA）的严重程度进行分类。实验装置考虑了三种类型的测量，使用八个电极：相邻模式的全球阻抗、相反模式的全球阻抗以及直接阻抗测量。这些测量是通过作者提出的基于Analog Devices AD5933阻抗转换器的电子设备进行的。研究纳入了37名参与者，其中25名膝关节健康，13名患有不同程度KOA。所有参与者均重复执行以下五种任务各20次：（i）膝盖弯曲时的坐姿，（ii）膝盖伸直时的坐姿，（iii）坐姿下连续进行膝盖的伸展和屈曲，（iv）站立，（v）行走。15个实验装置（3种测量类型×5种锻炼）的数据被用于训练一个多分类随机森林。使用随机抽样重复了100次训练和验证周期。在每个100个周期中，80%的数据用于训练，其余用于测试。结果显示，所提出的方法在伸展、循环和步态任务中的四个类别中实现了100%的平均敏感性和特异性。这表明，所提出的方法可以作为筛选工具，以确定哪些个体应接受X射线或磁共振成像以进一步评估KOA。生物阻抗测量（BIM）使用的是先前开发的定制八通道电子原型。BIM系统集成了AD5933阻抗转换器，该转换器产生一个50 kHz的交流电压信号。然后，使用电压控制电流源将该信号转换为1 mA的交流电流。使用了两组74HC4067多路复用器，其中一对用于选择电流注入的电极，另一对用于选择电压测量的电极。电极放置在膝盖周围的额面平面内，形成一个圆形。生物阻抗测量系统在本链接中进行了描述：https://doi.org/10.1016/j.ohx.2022.e00274