title: Optimal placement and angulation of a dorsal motion control mechanism to resist heel rise in an orthosis.
abstract: BACKGROUND
  No studies have determined the optimal location and angular orientation for orthotic dorsal control mechanisms (e.g. dorsal foot strap) for use in lower limb orthoses to resist foot motion for maximum user function and comfort.
  
  
  OBJECTIVE
  To determine the optimal dorsal location and angular orientation of an orthotic control mechanism to resist foot movements associated with heel rise.
  
  
  METHODS
  An in vitro cadaveric study quantified the dorsal force required to resist foot motion.
  
  
  METHODS
  The study simulated heel rise and quantified the force of a dorsal control mechanism in nine test conditions comprising three angles (75°, 90°, and 105°) and three longitudinal axis positions at 2.0 cm increments.
  
  
  RESULTS
  The test condition representing the longest lever arm (proximal location) applied at an obtuse angle (105°) required the least force (55.6 N) to constrain foot motion, whereas the shortest lever arm (distal location) at the acute angle (75°) required the greatest force (90.4 N) to constrain foot motion.
  
  
  CONCLUSIONS
  To resist foot motion relative to the orthosis, clinicians should aim for the most proximal placement (longest lever arm) at an obtuse angle (105°) with the intention that the resultant controlling force be perpendicular to the bony structure.
  
  
  CONCLUSIONS
  A dorsal foot control strap applies a critical orthotic corrective force, as part of a force couple to restrict motion of the foot and shank in lower limb orthoses. Foundational orthotic principles that stipulate optimal clinical placement and angular orientation are necessary to ensure maximum function and comfort to users.
authors.affiliation: Clinical Biomechanics Laboratory, School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA geza@gatech.edu.
authors.forename: Géza F
authors.initials: GF
authors.lastname: Kogler
authors.affiliation: Clinical Biomechanics Laboratory, School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Kalyn M
authors.initials: KM
authors.lastname: Conner
authors.affiliation: Clinical Biomechanics Laboratory, School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Manee
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D002102:Cadaver; D004867:Equipment Design; D005528:Foot / Q000033:anatomy & histology / Q000502:physiology*; D061826:Foot Orthoses; D006801:Humans; D009068:Movement / Q000502:physiology*
keywords: Orthotics; biomechanics; biomechanics of prosthetic/orthotic devices; lower limb orthotics