Knee bioelectric impedance assessment in healthy/with osteoarthritis subjects

The present study analyzes parameters estimated by bioelectric impedance spectroscopy (BIS) in subjects with healthy and with osteoarthritis (OA) knees. Thirty-two male volunteers, members of the Parachute Military Infantry Brigade of Rio de Janeiro, Brazil, participated in the study (62 knee joints). Clinical specialists used the Dejour scale for OA classification and divided the subjects into a control (without OA) and a pathological group (with different degrees of OA). BIS data were obtained in a standing position using a BIS technique based on the current response to a step voltage excitation. Differences between groups were measured by means of a Wilcoxon-Mann-Whitney test. Results indicate that raw bioimpedance parameters seem to be sensitive to the physiological changes associated with OA. Thus, data indicate that extra-cellular resistance (Re) and reactance of the equivalent capacitance (Xcx) increase according to the disease intensity (p < 0.001). In conclusion, the BIS technique seems to be able to provide the objective and non-invasive basis for helping the diagnosis of knee OA.