Radiographic Measurements on Hindfoot Alignment View in 1,128 Asymptomatic Subjects

CATEGORY: Hindfoot INTRODUCTION/PURPOSE: The primary aim of this study was to calculate the mean values of three most frequently measured parameters for hindfoot alignment determination in asymptomatic subjects - hindfoot alignment angle (HAA), hindfoot alignment ratio (HAR), and hindfoot moment arm (HMA). The secondary aim was to determine the relationship between HAR and HAA or HMA using statistical methods. METHODS: From January 2014 to June 2019, a total of 1128 asymptomatic subjects were enrolled in this study. With the hindfoot alignment view by Saltzman and el-Khoury, HAA, HAR, and HMA were measured to evaluate the degree of hindfoot varus or valgus deviation. All subjects were divided into subgroups according to sex and age (<45 years old vs >=45 years old). Simple linear regression was performed to draw out the regression formula between HAR and HAA or HMA. RESULTS: The mean HAA, HAR, and HMA for all subjects were -4.07+-3.48o, 0.21+-0.15, and -6.12+-5.22 mm, respectively. By comparing subgroups, female subjects >=45 years old showed the largest valgus deviation (-7.08+-6.34o, P=0.001). To predict HAR using HAA or HMA, the regression formulas were ‘HAR= 0.366 + 0.039 × HAA’ and ‘HAR= 0.361 + 0.025 × HMA.’ CONCLUSION: Under HAA, HAR, and HMA evaluation, the hindfoot alignment for asymptomatic subjects was valgus deviation. Furthermore, the degree of valgus deviation was the largest in female subjects aged 45 years or older. This can be explained as the progression of adult type flat foot deformity with aging.