title: Understanding responses to gait instability from plantar pressure measurement and the relationship to balance and mobility in lower-limb amputees.
abstract: BACKGROUND
  Measuring responses to a more unstable walking environment at the point-of-care may reveal clinically relevant strategies, particularly for rehabilitation. This study determined if temporal measures, center of pressure-derived measures, and force impulse measures can quantify responses to surface instability and correlate with clinical balance and mobility measures.
  
  
  METHODS
  Thirty-one unilateral amputees, 11 transfemoral and 20 transtibial, walked on level and soft ground while wearing pressure-sensing insoles. Foot-strike and foot-off center of pressure, center of pressure path, temporal, and force impulse variables were derived from F-Scan pressure-sensing insoles.
  
  
  RESULTS
  Significant differences (P<0.05) between level and soft ground were found for temporal and center of pressure path measures. Twenty regression models (R(2) ≤ 0.840), which related plantar-pressure-derived measures with clinical scores, consisted of nine variables. Stride time was in eight models; posterior deviations per stride in six models; mean CoP path velocity in five models; and anterior-posterior center of pressure path coefficient of variation, percent double-support time, and percent stance in four models.
  
  
  CONCLUSIONS
  Center of pressure-derived parameters, particularly temporal and center of pressure path measures, can differentiate between level and soft ground walking for transfemoral and transtibial amputees. Center of pressure-derived parameters correlated with clinical measures of mobility and balance, explaining up to 84.0% of the variability. The number of posterior deviations per stride, mean CoP path velocity stride time, anterior-posterior center of pressure path coefficient of variation, percent double-support time, and percent stance were frequently related to clinical balance and mobility measures.
authors.affiliation: Department of Systems Design Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada. Electronic address: j2irwin@uwaterloo.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Howcroft
authors.affiliation: Ottawa Hospital Research Institute, Centre for Rehabilitation, Research and Development, 505 Smyth Road, Ottawa, ON K1H 8M2, Canada; Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada. Electronic address: elemaire@ottawahospital.on.ca.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Lemaire
authors.affiliation: Department of Systems Design Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada. Electronic address: jkofman@uwaterloo.ca.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Kofman
authors.affiliation: Cancer Outcomes Research Program, Department of Surgery, Dalhousie University/Capital Health, Halifax, NS B3H 3J5, Canada. Electronic address: kendellcynthia@gmail.com.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Kendell
mesh_terms: D000328:Adult; D000368:Aged; D000674:Amputees / Q000534:rehabilitation*; D001186:Artificial Limbs; D005260:Female; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; D016138:Walking / Q000502:physiology
keywords: Center of pressure; Gait; Plantar pressure; Stability; Transfemoral amputee; Transtibial amputee