Reliability of water volumetry and the figure of eight method on subjects with ankle joint swelling

Study Design: Single-group repeated measures with 2 raters. Objectives: To determine the interrater and intrarater reliability of water volumetry and the figure of eight method on subjects with ankle joint swelling. Background: Measurements of ankle swelling are commonly performed to determine the nature and stage of injury and to monitor progress made during rehabilitation. Water volumetry and the figure of eight method are 2 techniques used to measure ankle swelling. Methods and Measures: Twenty-nine subjects with ankle swelling were measured by 2 raters with the hypothesis that both measurement techniques would be reliable. Each rater performed 3 measurements of the swollen ankle using both measurement techniques during a single test session. The order of the rater and of the measurement technique was randomized, and the raters were blinded to each other's measurements. Results: We found high interrater reliability for both the water volumetry (ICC [intraclass correlation coefficient] = 0.99) and figure of eight methods (ICC = 0.98). Additionally, intrarater reliability was high for both raters using both methods (ICCs = 0.98-0.99). Conclusions: Both methods are reliable measures of ankle swelling. The authors recommend the figure of eight method because of its ease of use, time efficiency, and cost effectiveness. However, water volumetry may be more appropriate when measuring diffuse lower-extremity swelling. Reliability of these 2 methods was established using subjects with foot or ankle pathology. Therefore, the results are applicable and generalizable to the clinical setting.