A finite element model of knee electrical bioimpedance for facilitating edema quantification

Electrical bioimpedance (EBI) is a non-invasive technique for quantifying the composition of biological tissue. Recent work has shown empirically that vector EBI measurements can potentially be used to assess knee health after acute injury: edema leads to decreased local tissue resistance and injury to cell membranes increases local reactance. However, there is a need to better understand the underlying factors that can affect knee EBI measures, including parameters associated with the injury (e.g., location, severity), measurement (e.g., electrode placement, frequency), and environment (e.g., ambient temperature). In this paper, we present a subject-specific finite element method (FEM) model of a human knee with edema, with a preliminary investigation of these underlying factors that can affect EBI measures. Two shapes are considered for the knee and contrasted: a cylinder and a truncated cone. These models allow us to perform initial analyses to determine the effects of edema volume on EBI changes. Additionally, the models are compared with experimental results from subjects with acute knee injury using a system our group has previously developed and tested for high-resolution EBI measurements.