title: Adding loads to occupied wheelchairs: effect on static rear and forward stability.
abstract: OBJECTIVE
  To determine the extent to which loads added in different positions affect the static rear and forward stability of an occupied wheelchair.
  
  
  METHODS
  Controlled, cross-over study.
  
  
  METHODS
  Loads from 0 to 10kg (in 1-kg increments) were added to five positions: high rear (HR), low rear (LR, beneath the seat and behind the crossbrace), on the lap (LAP), low anterior (LA, beneath the seat and anterior to the crossbrace), and on the footrests (FR). We also used a computer model to evaluate the relationship between stability and load, with a range of loads (0 to 100kg, in 10-kg increments) beyond the loads that were practical to test empirically.
  
  
  METHODS
  On a tilting platform, we measured the static stability (in degrees) of a wheelchair occupied by an anthropomorphic test dummy (ATD).
  
  
  RESULTS
  The greatest increase in rear stability was with FR loads, changes of 64% and 227% for 10-kg and 100-kg loads, respectively. Only HR loads reduced rear stability, by 32% and 64%. The greatest increase in forward stability was with LR loads, by 13% and 92%. The greatest reduction in forward stability was with FR loads, by 10% and 149%. To minimize the effect of added loads on stability, the LAP and LA positions would be preferred.
  
  
  CONCLUSIONS
  Added loads affect wheelchair stability as a function of the load magnitude. The extent and direction of the effect is profoundly influenced by load position.
authors.affiliation: Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: R L
authors.initials: RL
authors.lastname: Kirby
authors.forename: B D
authors.initials: BD
authors.lastname: Ashton
authors.forename: S A
authors.initials: SA
authors.lastname: Ackroyd-Stolarz
authors.forename: D A
authors.initials: DA
authors.lastname: MacLeod
mesh_terms: D000059:Accidents; D003198:Computer Simulation; D018592:Cross-Over Studies; D004867:Equipment Design; D004868:Equipment Failure; D006804:Ergonomics; D006801:Humans; D008297:Male; D008348:Manikins; D011187:Posture; D016474:Weight-Bearing; D014910:Wheelchairs / Q000009:adverse effects / Q000592:standards*