Defining Inversion/Eversion of the Foot : Is it a Triplane Motion or a Coronal Plane Motion?

Abstract

The purpose of this study was to resolve the confusion existing in the terminology for describing foot motion, particularly the definitions of inversion and eversion. First, the definitions of foot motion used by the Japanese Association of Rehabilitation Medicine and the Japanese Orthope-dic Association were compared with those used by the American Orthopaedic Foot and Ankle Society AOFASand with those used by the International Society of BiomechanicsISB , to identify agree-ments and differences. Next, the terminology utilized in the literature was explored by examining sev-eral major textbooks and related academic papers retrieved through a search of the PubMed medical literature database. In the definitions of AOFAS and ISB, inversion and eversion, which correspond to triplane motions in the definition used in Japan, were regarded as motions in the coronal plane. Ter-minology in the textbooks was very diverse. Of the 141 academic papers explored, 92 papers66 regarded inversioneversion as coronal plane motion, and 4 papers3regarded it as a triplane motion. In the remaining 43 papers31 , the definition was unspecified. In academic articles addressing foot motions, to avoid confusion in terminology, the definitions of inversion and eversion need to be specified.Jpn J Rehabil Med 2007286 292