Comparison of three methods used to obtain a neutral plaster foot impression.

The purpose of our study was to compare the forefoot-to-hindfoot angles obtained from three methods used to obtain a neutral plaster impression of the foot. The three methods were 1) supine nonweight-bearing (S), 2) prone nonweight-bearing (P), and 3) sitting semiweight-bearing (SW). We obtained foot casts from both feet of 11 female subjects for each of the three methods and used a manual goniometer to measure the forefoot-to-hindfoot angle for each pair of casts. The F ratios were significant for the variables left-right foot (p less than .0001) and impression method (p less than .001) using a within-subject two-factor analysis of variance. The impression methods S and P were found to be significantly different from SW, but not significantly different from each other, using a Tukey's post hoc comparison. The results indicate that the same forefoot-to-hindfoot alignment can be obtained using either the S or P method but not with the SW method.