Radiographic measurements on hindfoot alignment view in 1128 asymptomatic subjects

• We studied the mean values of three frequently measured parameters for hindfoot alignment with a large number. • We focused on hindfoot alignment angle (HAA), hindfoot alignment ratio (HAR) and hindfoot moment arm (HMA) • The mean HAA, HAR, and HMA for all subjects indicated valgus deviation of the hindfoot alignment. • The degree of valgus deviation was the largest in female subjects aged 45 years or older. The primary aim of this study was to determine the mean values for three of the most common parameters measured to assess hindfoot alignment in asymptomatic subjects: hindfoot alignment angle (HAA), hindfoot alignment ratio (HAR), and hindfoot moment arm (HMA). The secondary aim was to evaluate the mean value of each parameter according to age and sex. We assessed 1128 asymptomatic subjects from January 2014 to June 2019. HAA, HAR and HMA were measured to evaluate the degree of hindfoot varus or valgus deviation on the hindfoot alignment view, described by Saltzman and el-Khoury. All subjects were divided into subgroups according to sex and age (<45 years versus ≥45 years). The overall mean HAA, HAR, and HMA were –4.07 ± 3.48°, 0.21 ± 0.15, and –6.12 ± 5.22 mm, respectively. Female subjects ≥45 years old had the largest valgus deviation (HAA, –7.08 ± 6.34°; HAR 0.09 ± 0.25; HMA, –10.58 ± 11.46 mm). HAA, HAR, and HMA evaluation revealed that asymptomatic subjects had a hindfoot alignment with valgus deviation. Furthermore, the degree of valgus deviation was the largest in female subjects aged ≥45 years. We hope that the results of our study will be helpful to inform other researchers about the usefulness of these parameters as references.