title: Biomechanical gait characteristics of naturally occurring unsuccessful foot clearance during swing in individuals with chronic stroke.
abstract: BACKGROUND
  Altered gait mechanics are common following stroke and may increase the risk of falls. Paretic gait impairments have been previously compared to the non-paretic limb or control participants. Unfortunately, the biomechanical parameters underlying instances of naturally occurring unsuccessful foot clearance (trips) have yet to be examined in individuals with chronic stroke.
  
  
  METHODS
  Gait data from 26 participants with chronic stroke were obtained on a dual-belt instrumented treadmill. Instances of successful and unsuccessful foot swing were identified. Temporal, kinematic, and kinetic measures of the paretic limb occurring during late stance, toe-off, and swing were compared between trip and non-trip steps using paired samples t-tests. An α = 0.004 was used to adjust for multiple comparisons.
  
  
  RESULTS
  In the paretic limb, the ankle angle at toe off (P = 0.003; d = 0.64), knee flexion velocity at toe off (P < 0.001; d = 0.73), and peak knee extension moment during terminal stance (P < 0.001; d = 0.74) were significantly different between trips and non-trip steps. During trip steps, ankle plantarflexion at toe-off was 1.0° greater, knee flexion velocity was reduced by 17.6°/sec, and peak knee extension moment was increased by 0.011 Nm/kg · m compared to non-trip steps.
  
  
  CONCLUSIONS
  It appears to take only minor changes in the movement of the paretic limb to result in a trip in individuals with chronic stroke. Although small, the multi-joint biomechanical changes occurring in the paretic limb during unsuccessful foot clearance result in a functionally longer limb. Thus, interventions targeting multiple joints in the paretic limb may be needed to reduce the risk of trips following stroke.
authors.affiliation: Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Burpee
authors.affiliation: Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: mlewek@med.unc.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Lewek
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle / Q000503:physiopathology*; D000843:Ankle Joint; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint; D008875:Middle Aged; D015233:Models, Statistical; D009068:Movement; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D016138:Walking
keywords: Biomechanics; Gait; Stroke; Trip