Metabolic Cost Savings for Transtibial Amputees Wearing the Controlled Energy Storage and Return (CESR) Foot
Condition: Transtibial Amputation
Study type: Interventional
Phase: Phase 3

Summary: 
      To determine if below-knee amputees will walk with better efficiency wearing a CESR foot
      which stores energy at heel strike and releases energy releases energy during push-off.
    

Detailed description: 
      Amputees work harder and have greater oxygen cost during ambulation compared to those without
      limb loss. Therefore, amputees generally walk slower and tire more easily than intact
      individuals. The loss of the ankle as a propulsive and supportive joint requires the amputee
      to perform extra muscular work with the hip, trunk and contralateral limb during ambulation.
      This increased muscular activity consumes additional metabolic energy and means that amputees
      have to work harder to walk at the same speed as intact individuals. For some amputees, this
      extra effort is simply not possible, and their loss of functional ambulation leads to a
      progressive spiral of disuse, reduced capacity and more disuse. Conversely, greater mobility
      can lead to greater activity and even more successful return to the workplace. The health
      consequences for amputees who do not maintain functional ambulation is multifactorial and
      costly, not only in terms of dollars for the institutions committed to their care, but also
      for the individuals themselves in terms of decreased quality of life, increased disability
      and pain. Recent developments have resulted in the design of a novel prosthetic foot that
      uses the energy from compressive forces during heel contact, stores it throughout midstance
      and releases it at an optimal instant during push-off in late stance. This unique design,
      with Controlled Energy Storage and Release (CESR) developed by a team at the University of
      Michigan, Ann Arbor has been shown to reduce the metabolic cost penalty of prosthetic
      ambulation (i.e. the increased cost over normal walking) by 50% compared to a standard SACH
      foot, but as yet only intact individuals wearing an aircast boot equipped with the prosthetic
      feet have been studied. It is likely that the increased energy savings will also be observed
      in transtibial amputees. Young, active amputees will soon be entering the VA system following
      operations in Iraq and Afghanistan, and the energy improvements may benefit this new VA
      patient population. The CESR foot may also provide substantial metabolic cost savings to
      older less active amputees currently in the VA system. By improving gait efficiency amputees
      will be better able to keep up with the demands of functional ambulation, remain more active
      and postpone many of the debilitating consequences of limited mobility. Therefore we propose
      to first refine the design of the CESR foot focusing on the energy storage and energy release
      mechanisms of the CESR foot. Several spring characteristics may prove optimal for certain
      subjects depending upon weight and walking characteristics. This will be an iterative
      optimization process with power generation and absorption characteristics of the CESR foot
      evaluated using computerized gait analysis and the lessons used for further refinement. The
      second phase will involve a three week wear-testing trial to determine if any improvement in
      gait economy, reduction in fatigue, improvement in comfort, or increase in the amount of
      daily walking can be achieved. A validated questionnaire will be utilized to determine each
      amputee's comfort and fatigue during a three week trial in their conventional foot and with
      the CESR foot. Step counts will be performed on each individual over the entire 3 week period
      with both the conventional foot and with the CESR foot. We will collect full body gait
      kinematics (motion) and kinetics (forces) using our Vicon 612 system, and metabolic
      measurements using our VmaxST to calculate oxygen cost for 24 transtibial amputees while
      walking with the CESR foot and their conventional foot. This will permit the calculation of
      the energy storage and release of the foot by inverse dynamics and calculate the net effect
      upon metabolic energy cost savings during ambulation at several speeds. If the CESR foot is
      successful in amputee gait these domains, our next step will be to perform a multi-center
      study with other VA motion laboratories, and eventually collaborate with Ohio Willow Wood, a
      prominent prosthetic manufacturer who has expressed an interest in bringing the CESR foot to
      market.
    

Intervention name(s): CESR Prosthetic Foot; typical prosthetic foot; standardized prosthetic foot
Intervention type(s): Device; Device; Device
Intervention description(s): a novel prosthetic foot that is designed to store energy and release it at a predetermined time in the gait cycle; patients will wear the prosthetic foot that they were prescribed by the care providers in the clinical team; a standard foot that has had weights applied to match the mass of the CESR foot
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Amputee; Economy; Efficiency; Foot; Gait; Kinematics; Kinetics; Prosthesis