title: Effect of medial arch-heel support in inserts on reducing ankle eversion: a biomechanics study.
abstract: BACKGROUND
  Excessive pronation (or eversion) at ankle joint in heel-toe running correlated with lower extremity overuse injuries. Orthotics and inserts are often prescribed to limit the pronation range to tackle the problem. Previous studies revealed that the effect is product-specific. This study investigated the effect of medial arch-heel support in inserts on reducing ankle eversion in standing, walking and running.
  
  
  METHODS
  Thirteen pronators and 13 normal subjects participated in standing, walking and running trials in each of the following conditions: (1) barefoot, and shod condition with insert with (2) no, (3) low, (4) medium, and (5) high medial arch-heel support. Motions were captured and processed by an eight-camera motion capture system. Maximum ankle eversion was calculated by incorporating the raw coordinates of 15 anatomical positions to a self-compiled Matlab program with kinematics equations. Analysis of variance with repeated measures with post-hoc Tukey pairwise comparisons was performed on the data among the five walking conditions and the five running conditions separately.
  
  
  RESULTS
  Results showed that the inserts with medial arch-heel support were effective in dynamics trials but not static trials. In walking, they successfully reduced the maximum eversion by 2.1 degrees in normal subjects and by 2.5-3.0 degrees in pronators. In running, the insert with low medial arch support significantly reduced maximum eversion angle by 3.6 and 3.1 degrees in normal subjects and pronators respectively.
  
  
  CONCLUSIONS
  Medial arch-heel support in inserts is effective in reducing ankle eversion in walking and running, but not in standing. In walking, there is a trend to bring the over-pronated feet of the pronators back to the normal eversion range. In running, it shows an effect to restore normal eversion range in 84% of the pronators.
authors.affiliation: Department of Orthopaedics and Traumatology, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Daniel Tp
authors.initials: DT
authors.lastname: Fong
authors.forename: Mak-Ham
authors.initials: MH
authors.lastname: Lam
authors.forename: Miko Lm
authors.initials: ML
authors.lastname: Lao
authors.forename: Chad Wn
authors.initials: CW
authors.lastname: Chan
authors.forename: Patrick Sh
authors.initials: PSh
authors.lastname: Yung
authors.forename: Kwai-Yau
authors.initials: KY
authors.lastname: Fung
authors.forename: Pauline Py
authors.initials: PP
authors.lastname: Lui
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chan