title: The effects of transverse rotation angle on compression and effective lever arm of prosthetic feet during simulated stance.
abstract: OBJECTIVE
  Unlike sagittal plane prosthesis alignment, few studies have observed the effects of transverse plane alignment on gait and prosthesis behaviour. Changes in transverse plane rotation angle will rotate the points of loading on the prosthesis during stance and may alter its mechanical behaviour. This study observed the effects of increasing the external transverse plane rotation angle, or toe-out, on foot compression and effective lever arm of three commonly prescribed prosthetic feet.
  
  
  METHODS
  The roll-over shape of a SACH, Flex and single-axis foot was measured at four external rotation angle conditions (0°, 5°, 7° and 12° relative to neutral). Differences in foot compression between conditions were measured as average distance between roll-over shapes.
  
  
  CONCLUSIONS
  Increasing the transverse plane rotation angle did not affect foot compression. However, it did affect the effective lever arm, which was maximized with the 5° condition, although differences between conditions were small.
  
  
  CONCLUSIONS
  Increasing the transverse plane rotation angle of prosthetic feet by up to 12° beyond neutral has minimal effects on their mechanical behaviour in the plane of walking progression during weight-bearing.
authors.affiliation: Northwestern University Prosthetics-Orthotics Center, Chicago, IL 60611, USA. mattyj.major@gmail.com
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Major
authors.forename: David
authors.initials: D
authors.lastname: Howard
authors.forename: Rebecca
authors.initials: R
authors.lastname: Jones
authors.forename: Martin
authors.initials: M
authors.lastname: Twiste
mesh_terms: D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D005528:Foot; D005684:Gait; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012399:Rotation; D016474:Weight-Bearing