Reliability, Validity, and Feasibility of Water Displacement Method, Figure-of-Eight Method, and Circumference Measurements in Determination of Ankle and Foot Edema

Background: To compare interrater reliability and the time-efficiency for the water displacement method, figure-of-eight method, and circumference measurements of the ankle and foot, and to investigate concurrent validity of the figure-of-eight method and circumference measurements with the water displacement method. Methods and Results: Thirty patients (21 women and 9 men) with primary or secondary lower limb lymphedema were evaluated twice. The volume of the foot and ankle was measured in three different ways: water displacement with a volumeter, figure-of-eight method, and circumference measurements at the level of the malleoli and metatarsals with a tapeline. The intraclass correlation coefficients (ICCs) ranged from good to excellent for all measurements (ICCs = 0.99 for water displacement; 0.94 for figure-of-eight; 0.80 and 0.79 for circumference measurement at malleolus and metatarsals). More time was needed to perform the water displacement method than the figure-of-eight method and the circumference measurements (p < 0.001). There was a statistically significant moderate correlation between the water displacement method and the figure-of-eight method (r = 0.65; p < 0.001), whereas the correlation coefficient between water displacement method and circumference measurements at malleolus and metatarsals was weak (r = 0.51, p < 0.001 and r = 0.34, p = 0.06, respectively). Conclusions: Compared to the water displacement method, reliability of the figure-of-eight method is comparable, time-efficiency is better and concurrent validity is acceptable. So, in clinical practice, the figure-of-eight method is a good alternative for the water displacement method to evaluate the volume of the foot and ankle.