title: Restricting ankle motion via orthotic bracing reduces toe clearance when walking over obstacles.
abstract: BACKGROUND
  When trans-tibial amputees cross obstacles leading with their prosthesis, foot clearance is achieved using compensatory swing-phase kinematics. Such compensation would suggest able-bodied individuals normally use swing-phase ankle dorsiflexion to attain adequate obstacle clearance; however, direct evidence of such contribution is equivocal. This study determined the contribution of sagittal plane ankle motion in achieving lead-limb clearance during obstacle negotiation.
  
  
  METHODS
  Twelve male able-bodied individuals (ages 18-30) completed obstacle crossing trials while walking on a flat surface. Lead-limb (right) ankle motion was manipulated using a knee-ankle-foot orthosis. Trials were completed with the ankle restricted at a neutral angle or unrestricted (allowing ∼±15° plantar/dorsiflexion).
  
  
  RESULTS
  Restricted ankle motion caused significant increase in trail-limb foot placement distance before the obstacle (p=0.005); significant decrease in vertical toe clearance (p<0.003), vertical heel clearance (p=0.045), and lead-limb foot placement distance after the obstacle (p=0.045); but no significant changes in knee angle at instant of crossing or in average walking speed.
  
  
  CONCLUSIONS
  The shifts in foot placements altered the part of swing that the lead-limb was in when the foot crossed the obstacle, which led to a decrease in clearance. These adaptations may have been due to being unable to dorsiflex the ankle to 'lift' the toes in mid-swing or to plantarflex the ankle during initial contact following crossing, which changed how the lead-limb was to be loaded. These findings suggest individuals using ankle bracing or those with ankle arthrodesis, will have reduced gait safety when negotiating obstacles.
authors.affiliation: Division of Medical Engineering, School of Engineering, University of Bradford, Bradford BD7 1DP, United Kingdom. Electronic address: E.Evangelopoulou@edu.salford.ac.uk.
authors.forename: Eftychia
authors.initials: E
authors.lastname: Evangelopoulou
authors.affiliation: Centre for Health Sciences Research, Brian Blatchford Building, University of Salford, Manchester M6 6PU, United Kingdom; UNIPOD - United National Institute for Prosthetics & Orthotics Development, University of Salford, United Kingdom. Electronic address: M.Twiste@salford.ac.uk.
authors.forename: Martin
authors.initials: M
authors.lastname: Twiste
authors.affiliation: Division of Medical Engineering, School of Engineering, University of Bradford, Bradford BD7 1DP, United Kingdom. Electronic address: J.Buckley@bradford.ac.uk.
authors.forename: John G
authors.initials: JG
authors.lastname: Buckley
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D000842:Ankle / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D009989:Orthotic Devices; D016059:Range of Motion, Articular; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Ankle; Foot clearance; Gait; Obstacle crossing; Orthotics