BACKGROUND
Exact quantification of volumetric changes of the extremities is difficult. There are several direct and indirect methods to assess extremity volume. As water displacement volumetry is rarely viable in a clinical setting and circumference measurements are prone to errors due to poor reproducibility and high inter- and intra-observer variability, an objective and easily reproducible method is indispensable.
OBJECTIVE
The aim of this study was to establish a standardized method based on 3D scans with defined caudal and cranial landmarks of the lower leg which allows for measurements of exactly the same body area. Furthermore, this study tests the method in terms of reproducibility and evaluates volume changes after surgical therapy in patients suffering from lymphedema.
METHODS
3D-scans of the lower limb were performed with a mobile 3D-scanner. Volumetric calculation was done digitally. “Repeatability“ and “Inter-observer reliability” of digital volumetry were tested. Furthermore, the method was applied on 31 patients suffering from chronic lymphedema. ANOVA (analyses of variance) was conducted to compare the digital volumetric measurements. To assess the sensitivity to changes in digital volumetry, the mean volume of 31 patients before and 3 months after therapy were compared by a paired t-Test.
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 7 measurements of the 3 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 costs, it is reproducible and precise and therefore ideal for evolution of therapy in lymphedema.
