Digital volumetric measurements based on 3D scans of the lower limb: A valid and reproducible method for evaluation in lymphedema therapy

Introduction Exact quantification of volumetric changes of the extremities is difficult and often error prone. The aim of this study was to establish a standardized method based on 3D scans. Furthermore, this study tests the method in terms of reproducibility and evaluates volume changes after surgical therapy in patients suffering from lymphedema on the lower extremity. Methods 3D-scans of the lower limb were performed with a mobile 3D-scanner. “repeatability“ and “inter-observer reliability” of digital volumetry were tested. Furthermore, the method was applied on 31 patients suffering from chronic lymphedema. Results Calculations of repeatability of the volume based on 20 3D-scans of the same lower leg showed a mean volume of 2.488 ± 0,011 liters (range: 2.470 – 2.510). The mean volume of the different examiners did not differ significantly (F(2,18) = 1.579, p = .233). The paired t-Test showed a significant mean volume decrease of 375ml (95% CI = 245/505ml) between pre and post treatment (t (30) =5.892, p < .001). Conclusions 3D-Volumetry is a noninvasive, easy and quick method to assess volume changes of the lower leg. Other than the low costs, it is reproducible and precise and therefore ideal for evolution of therapy in lymphedema.