FOOT VOLUME ESTIMATES BASED ON A GEOMETRIC ALGORITHM IN COMPARISON TO WATER DISPLACEMENT

Abstract

Assessing lower extremity limb volume and its change during and after lymphedema therapyis important for determining treatment efficacy and documenting outcomes. Although legvolumes may be determined by tape measure and other methods, there is no metric method toroutinely assess foot volumes. Exclusion of foot volumes can under- or overestimate therapeuticprogress. Our aim was to develop and test a metric measurement procedure and algorithm forpracticing therapists to use to estimate foot volumes. The method uses a caliper and ruler tomeasure foot dimensions at standardized locations and calculates foot volume (VM) by amathematical algorithm. VM W was compared to volumes measured by water displacement (V ) in30 subjects (60 feet) using regression analysis and limits of agreement (LOA). VW M and V (mean± M W sd) were similar 857±150 ml vs. 859±154 ml, and were highly correlated V = 1.00V + 1.67ml, r=0.965, p<0.001. The LOA for absolute volume differences and percentages wererespectively ±79.6 ml and ±9.28 %. These results indicate that this metric method can be a usefulalternative to water displacement when foot volumes are needed, but the water displacementmethod is contraindicated, impractical to implement, too time consuming or is not available.