title: Dynamic input to determine hip joint moments, power and work on the prosthetic limb of transfemoral amputees: ground reaction vs knee reaction.
abstract: BACKGROUND
  Calculation of lower limb kinetics is limited by floor-mounted force-plates.
  
  
  OBJECTIVE
  Comparison of hip joint moments, power and mechanical work on the prosthetic limb of a transfemoral amputee calculated by inverse dynamics using either the ground reactions (force-plates) or knee reactions (transducer).
  
  
  METHODS
  Comparative analysis.
  
  
  METHODS
  Kinematics, ground reaction and knee reaction data were collected using a motion analysis system, two force-plates, and a multi-axial transducer mounted below the socket, respectively.
  
  
  RESULTS
  The inverse dynamics using ground reaction underestimated the peaks of hip energy generation and absorption occurring at 63% and 76% of the gait cycle (GC) by 28% and 54%, respectively. This method also overestimated by 24% a phase of negative work at the hip (37%-56% GC), and underestimated the phases of positive (57%-72% GC) and negative (73%-98%GC) work at the hip by 11% and 58%, respectively.
  
  
  CONCLUSIONS
  A transducer mounted within the prosthesis has the capacity to provide more realistic kinetics of the prosthetic limb because it enables assessment of multiple consecutive steps and a wide range of activities without the issue of foot placement on force-plates.
  
  
  CONCLUSIONS
  The hip is the only joint an amputee controls directly to set the prosthesis in motion. Hip joint kinetics are associated with joint degeneration, low back pain, risk of falls, etc. Therefore, realistic assessment of hip kinetics over multiple gait cycles and a wide range of activities is essential.
authors.affiliation: Group of Research on Adapted Physical Activities, University of Quebec, Montreal, Canada. laurentfrossard@yahoo.com.au
authors.forename: Laurent
authors.initials: L
authors.lastname: Frossard
authors.forename: Laurence
authors.initials: L
authors.lastname: Cheze
authors.forename: Raphael
authors.initials: R
authors.lastname: Dumas
mesh_terms: D000328:Adult; D000674:Amputees; D001186:Artificial Limbs; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005269:Femur / Q000601:surgery*; D033023:Foot Joints; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint; D009068:Movement; D011474:Prosthesis Design; D016138:Walking; D014937:Work