title: Attenuation of centre-of-pressure trajectory fluctuations under the prosthetic foot when using an articulating hydraulic ankle attachment compared to fixed attachment.
abstract: BACKGROUND
  Disruptions to the progress of the centre-of-pressure trajectory beneath prosthetic feet have been reported previously. These disruptions reflect how body weight is transferred over the prosthetic limb and are governed by the compliance of the prosthetic foot device and its ability to simulate ankle function. This study investigated whether using an articulating hydraulic ankle attachment attenuates centre-of-pressure trajectory fluctuations under the prosthetic foot compared to a fixed attachment.
  
  
  METHODS
  Twenty active unilateral trans-tibial amputees completed walking trials at their freely-selected, comfortable walking speed using both their habitual foot with either a rigid or elastic articulating attachment and a foot with a hydraulic ankle attachment. Centre-of-pressure displacement and velocity fluctuations beneath the prosthetic foot, prosthetic shank angular velocity during stance, and walking speed were compared between foot conditions.
  
  
  RESULTS
  Use of the hydraulic device eliminated or reduced the magnitude of posteriorly directed centre-of-pressure displacements, reduced centre-of-pressure velocity variability across single-support, increased mean forward angular velocity of the shank during early stance, and increased freely chosen comfortable walking speed (P ≤ 0.002).
  
  
  CONCLUSIONS
  The attenuation of centre-of-pressure trajectory fluctuations when using the hydraulic device indicated bodyweight was transferred onto the prosthetic limb in a smoother, less faltering manner which allowed the centre of mass to translate more quickly over the foot.
authors.affiliation: Division of Medical Engineering, School of Engineering, Design and Technology, University of Bradford, Bradford, BD7 1DP, UK.
authors.forename: Alan R
authors.initials: AR
authors.lastname: De Asha
authors.forename: Louise
authors.initials: L
authors.lastname: Johnson
authors.forename: Ramesh
authors.initials: R
authors.lastname: Munjal
authors.forename: Jai
authors.initials: J
authors.lastname: Kulkarni
authors.forename: John G
authors.initials: JG
authors.lastname: Buckley
mesh_terms: D000328:Adult; D000674:Amputees; D000843:Ankle Joint / Q000503:physiopathology*; D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D011312:Pressure; D011474:Prosthesis Design / Q000295:instrumentation*; D016138:Walking / Q000502:physiology