Effects of Wearing a Powered Ankle-Foot Prosthesis on Amputee Walking

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00869947
Recruitment Status : Completed
First Posted : March 26, 2009
Results First Posted : February 25, 2014
Last Update Posted : February 25, 2014
Massachusetts Institute of Technology
Information provided by (Responsible Party):
VA Office of Research and Development

Brief Summary:

Amputees wearing a conventional prosthesis require 20-30% more metabolic energy to walk at the same speeds as non-amputees and this discrepancy is more apparent at faster walking speeds. Amputees choose to walk at speeds 30-40% slower than non-amputees. Preferred walking speed is likely influenced by elevated metabolic energy, but the underlying reason for slower preferred walking speeds is not fully understood. Unilateral amputees exhibit highly asymmetrical gait patterns that likely require more metabolic energy and impair functional mobility, increasing the risk of degenerative joint disease, osteo-arthritis and lower back pain. Improvements in prosthetic devices could enhance mobility in amputees, thus positively effecting rehabilitation and ambulation in veterans. A prosthesis that allows amputees to reduce metabolic energy would be especially useful for rehabilitation in older, ill individuals with reduced exercise capacities and could literally restore walking ability in people that are currently non-ambulatory.

Hypotheses. Amputees wearing the Massachusetts Institute of Technology (MIT) Powered Ankle-Foot (PAF) prosthesis will have a lower metabolic cost, faster preferred walking speed, and improved gait symmetry during walking than amputees wearing a conventional prosthesis and will have nearly the same metabolic cost, preferred walking speed, and gait symmetry during walking as age, gender, height, and weight matched non-amputees.

Condition or disease Intervention/treatment Phase
Traumatic Amputation of Lower Extremity Device: Powered ankle-foot prosthesis Other: No device Not Applicable

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 16 participants
Allocation: Non-Randomized
Intervention Model: Factorial Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Effects of Wearing a Powered Ankle-Foot Prosthesis on Amputee Walking
Study Start Date : March 2009
Actual Primary Completion Date : June 2011
Actual Study Completion Date : January 2013

Resource links provided by the National Library of Medicine

U.S. FDA Resources

Arm Intervention/treatment
Experimental: Prosthesis
Powered ankle-foot prosthesis and passive-elastic prosthesis
Device: Powered ankle-foot prosthesis
The powered ankle-foot prosthesis is comprised of a series-elastic actuator (SEA) and an elastic leaf spring. This technology has been previously developed for robotic and human rehabilitation applications. The SEA allows for precise force control of the ankle joint, thus mimicking the spring-like behavior of the human ankle, as well as providing adequate energy for forward progression of the body. From the early stance period to the mid-stance period of walking, the SEA will be controlled so that the ankle joint behaves like a spring. During the late stance period, the SEA will be employed to power the forward movement of the body. The elastic leaf spring will provide shock absorption during foot strike, energy storage during early stance, and energy return during late stance.
Experimental: Non-amputee
Other: No device

Primary Outcome Measures :
  1. Metabolic Cost of Transport [ Time Frame: 1 year ]
    We measured and compared gross rates of oxygen consumption and carbon dioxide production using a portable metabolic analysis system (Cosmed K4b2, IT) while participants walked at five constance velocities (0.75, 1.00, 1.25, 1.50 and 1.75 m/s) on a level treadmill (SoleFitness F85). We calculated average steady-state metabolic power in Watts (W) from 4-6 min of each trial using a standard equation. Then, we divided the metabolic power by each participant's weight and velocity to calculate the metabolic cost of transport (J/Nm).

Secondary Outcome Measures :
  1. Preferred Walking Velocity [ Time Frame: 1 year ]
    We determined preferred walking velocity by incrementally increasing and decreasing treadmill velocity until each participant ascertained the velocity that they felt most comfortable.

  2. Trailing Leg Step-to-step Transition Work [ Time Frame: 1 year ]
    We calculated step-to-step transition work, the work done by each individual leg on the center of mass during transitions, using the individual limbs method described by Donelan et al. 2002. Trailing leg step-to-step transition work quantifies the amount of push-off work done by the trailing leg when both feet are on the ground during walking. Work (J) is normalized to each subject's mass (kg).

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Ages Eligible for Study:   18 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • 20 healthy adult volunteers, 10 unilateral trans-tibial amputees and 10 matched non-amputees, will be recruited and screened
  • Amputees must be at least 1 year post-amputation, high-functioning (at least a K3 level of ambulation), and whose cause of amputation is either traumatic or vascular. Medicare defines a K3 level amputee as an ambulator who has the ability or potential for prosthetic ambulation with variable cadence, who has the ability to traverse most environmental barriers and who may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion

Exclusion Criteria:

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00869947

United States, Rhode Island
VA Medical Center, Providence
Providence, Rhode Island, United States, 02908
Sponsors and Collaborators
VA Office of Research and Development
Massachusetts Institute of Technology
Principal Investigator: Alena Grabowski, PhD BA VA Eastern Colorado Health Care System, Denver, CO

Responsible Party: VA Office of Research and Development Identifier: NCT00869947     History of Changes
Other Study ID Numbers: A6749-M
First Posted: March 26, 2009    Key Record Dates
Results First Posted: February 25, 2014
Last Update Posted: February 25, 2014
Last Verified: January 2014

Keywords provided by VA Office of Research and Development:
Unilateral below the knee amputation

Additional relevant MeSH terms:
Amputation, Traumatic
Leg Injuries
Wounds and Injuries