title: A kinematic comparison of spring-loaded and traditional crutches.
abstract: BACKGROUND
  A novel spring-loaded-crutch design may provide patients additional forward velocity, relative to traditional axillary crutches; however, this idea has not yet been evaluated.
  
  
  OBJECTIVE
  To quantify elastic potential energy stored by spring-loaded crutches during crutch-ground contact and determine whether this energy increases forward velocity for patients during crutch ambulation. Because elastic potential energy is likely stored by the spring-loaded crutch during ambulation, the authors hypothesized that subjects would exhibit greater peak instantaneous forward velocity during crutch-ground contact and increased preferred ambulation speed during spring-loaded-crutch ambulation, relative to traditional-crutch ambulation.
  
  
  METHODS
  Within-subject.
  
  
  METHODS
  Biomechanics laboratory.
  
  
  METHODS
  10 healthy men and 10 healthy women.
  
  
  METHODS
  The independent variable was crutch type: Subjects used spring-loaded and traditional axillary crutches to ambulate at standardized and preferred speeds.
  
  
  METHODS
  The primary dependent variables were peak instantaneous forward velocity and preferred ambulation speed; these variables were quantified using high-speed videography and an optoelectronic timing device, respectively. Between-crutches differences for the dependent variables were evaluated using paired t tests (α = .05). Elastic potential energy stored by the spring-loaded crutches during crutch-ground contact was also quantified via videography.
  
  
  RESULTS
  Peak forward velocity during crutch-ground contact was 5% greater (P < .001) for spring-loaded-crutch ambulation than for traditional-crutch ambulation. Preferred ambulation speed, however, did not significantly differ (P = .538) between crutch types. The spring-loaded crutches stored an average of 2.50 ± 1.96 J of elastic potential energy during crutch-ground contact.
  
  
  CONCLUSIONS
  The spring-loaded crutches appear to have provided subjects with additional peak instantaneous forward velocity. This increased velocity, however, was relatively small and did not increase preferred ambulation speed.
authors.affiliation: Dept of Exercise Sciences, Brigham Young University, Provo, UT, USA.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Seeley
authors.forename: Iain
authors.initials: I
authors.lastname: Hunter
authors.forename: Thomas
authors.initials: T
authors.lastname: Bateman
authors.forename: Adam
authors.initials: A
authors.lastname: Roggia
authors.forename: Brad J
authors.initials: BJ
authors.lastname: Larson
authors.forename: David O
authors.initials: DO
authors.lastname: Draper
mesh_terms: D001696:Biomechanical Phenomena; D003446:Crutches; D004867:Equipment Design; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D055096:Optical Devices; D014741:Video Recording; D055815:Young Adult