A Comparison of Different Assessment Techniques for Measuring Foot and Ankle Volume in Healthy Adults

Abstract

Foot and ankle volume may be an important measurement for conditions such as lower-extremity trauma or pathologic abnormalities. Water volumetry, often used for this measure, is accurate but not always convenient. We used figure-of-eight tape measurement, prism approximation, foot size measurement (Brannock device), and optoelectric measurement (Perometer) with the standard of water volumetry to compare foot and ankle volumes. All five techniques were used to measure both the feet and ankles of ten asymptomatic men and women. Reliability was determined by repeating several trials, and validity was determined by comparing all of the techniques with water volumetry (the established standard). Regression equations were found that related each technique to water volumetry. All of the techniques were reliable (intraclass correlation coefficient[3,1] = 0.96-0.99). The figure-of-eight technique showed the highest agreement with water volumetry (R(2) = 0.96), and the prism method, the lowest (R(2) = 0.73). Although any of these techniques should be acceptable for monitoring foot and ankle volume in normal limbs, the figure-of-eight method comes closest to reproducing the results of water volumetry. We believe that this technique would also be best in the presence of foot deformities, but this remains to be studied.