Classification of frontal plane rearfoot motion patterns during the stance phase of walking

Background: Classification of rearfoot motion patterns would assist in understanding normal rearfoot motion and would facilitate the identification of abnormal motion. We sought to identify common frontal plane rearfoot motion patterns in an asymptomatic population. Methods: Frontal plane rearfoot motion was measured with an electromagnetic motion analysis system in 279 asymptomatic individuals during barefoot walking. The coefficient of multiple correlation and visual observation were used to identify similar patterns of rearfoot motion. Results: Four distinct rearfoot motion patterns were identified: pattern 1 consisted of 176 individuals (63.1%) and was labeled "typical" eversion, pattern 2 consisted of 87 individuals (31.2%) and was labeled "prolonged eversion," pattern 3 consisted of nine individuals (3.2%) and was labeled "delayed eversion," and pattern 4 consisted of seven individuals (2.5%) and was labeled "early eversion." Conclusions: Asymptomatic frontal plane rearfoot motion can be classified into four distinct patterns, but most individuals (94.3%) exhibit one of two motion patterns (typical or prolonged eversion).