Optimizing Prosthetic and Bicycle Fit for Veterans With Transtibial Amputations
Condition: Amputation
Study type: Observational

Summary: 
      Bicycling is a promising form of low-impact exercise that could prevent/treat Type 2
      diabetes. However, Veterans with transtibial amputations (TTAs) may not effectively utilize
      bicycling for rehabilitation and exercise due to improper bike fit, socket discomfort, and/or
      the potential for injury. An optimized prosthetic/bicycle fit could improve comfort and
      reduce injury risk by decreasing asymmetries between legs, lowering metabolic costs, and
      improving efficiency for Veterans with TTAs during bicycling. Moreover, the use of objective
      prosthetic/bicycle fit guidelines would allow clinicians to facilitate shorter appointment
      times and fewer revisits for Veterans with TTAs. The investigators will determine the
      physiological and biomechanical effects of different prosthetic and bicycle configurations
      for Veterans with a TTA to develop optimal prosthetic/bicycle fit guidelines. The
      investigators hypothesize that a longer prosthetic pylon length and shorter bicycle crank arm
      length for the affected compared to the unaffected leg along with a pedal attachment position
      beneath the pylon compared to beneath the forefoot will optimize performance for Veterans
      with TTAs the investigators' research will integrate evidence-based guidelines to advance
      rehabilitation and enhance the lives of Veterans with an amputation, thus improving and
      restoring their function.
    

Detailed description: 
      Over one million people in the United States have a leg amputation and this number continues
      to grow due to the prevalence of diabetes and recent military conflicts. Because of the
      functional impairment caused by an amputation, it is extremely important to advance
      rehabilitation that optimizes the use of prostheses so that Veterans with amputations can
      regain the greatest possible level of health, function, and physical activity. Low-impact
      exercise such as bicycling could facilitate return to work/duty after amputation by improving
      cardiovascular fitness, muscle strength, endurance, and quality of life for Veterans with
      transtibial amputations (TTAs). Bicycling as exercise could also prevent the deleterious
      effects of vascular disease and diabetes by improving cardiovascular function, controlling
      body weight, decreasing the rate of re-amputation, and improving quality of life for Veterans
      with TTAs. However, it is likely that discomfort and the increased potential for secondary
      musculoskeletal injury due to the lack of a proper prosthetic/bike fit discourages Veterans
      with TTAs from using bicycling for rehabilitation and exercise. Moreover, it is unclear how
      prosthetic and bicycle components, such as pylon length (PL), pedal attachment position (PAP)
      beneath the prosthetic forefoot versus the pylon, and crank arm length (CAL) affect the
      biomechanics, metabolic costs, and comfort/ satisfaction of Veterans with TTAs. Thus, the
      investigators' goal is to challenge the state-of-the-science by developing evidence-based
      prosthetic and bicycle fit guidelines that optimize the biomechanics, metabolic costs,
      efficiency (mechanical power/metabolic power) and comfort/satisfaction for Veterans with
      TTAs. The Department of Veterans Affairs (VA) and Department of Defense (DoD) Rehabilitation
      Directive has put forth an initiative that aims to dramatically improve and restore function
      in wounded Veterans and Service members so that they have the choice to return to active duty
      or productive civilian employment. The proposed research will establish optimal
      prosthetic/bicycle fit guidelines, which would enhance function by improving cardiovascular
      health, controlling body weight, decreasing re-amputation rates, and enhancing quality of
      life of Veterans with TTAs, thus helping to fulfill this initiative and having high potential
      impact. Specifically, the investigators aim to: 1) Study 15 Veterans with unilateral TTAs to
      determine the effects of systematically varying PL, PAP beneath the prosthetic forefoot
      versus the pylon, and CAL for the affected leg on bicycling biomechanics, metabolic costs,
      and comfort/satisfaction. 2) Synthesize and disseminate the investigators' findings into
      practical, evidence-based quantitative prosthetic/bicycle fit guidelines for Veterans with
      TTAs. The investigators hypothesize that a longer PL and shorter CAL for the affected
      compared to the unaffected leg along with a PAP beneath the pylon compared to beneath the
      forefoot will maximize mechanical power symmetry and reduce metabolic cost and muscle
      activity, and thus maximize efficiency and comfort/satisfaction during bicycling in Veterans
      with unilateral TTAs. The utilization of evidence-based prosthetic/bicycle fit guidelines
      that increase symmetry, improve comfort, reduce the risk of injury, decrease metabolic costs,
      and improve efficiency will directly benefit Veterans with TTAs by increasing their physical
      activity and function. Optimized prosthetic/bicycle fit guidelines will allow Veterans TTAs
      who were previously unable to comfortably ride a bicycle, as well as those currently riding a
      bicycle, to ride longer with less effort and discomfort, potentially leading to an improved
      quality of life. Moreover, the prosthetic/bicycle fit guidelines generated by this research
      will ensure that clinicians are able to fit Veterans with TTAs to bicycles more effectively,
      leading to shorter appointment times and fewer revisits due to enhanced function and reduced
      comorbidities.
    

Intervention name(s): Prosthetic/Bicycle Configuration
Intervention type(s): Other
Intervention description(s): The investigators will measure the biomechanics (motion, forces, and muscle activity) and metabolic rates while subjects ride using an initial bike fit and three taller pylon lengths (PL) for the affected leg (AL) in increments of 6.8 mm using a pedal attachment position (PAP) beneath the prosthetic forefoot. Then, using the optimal (most efficient) PL, the investigators will measure the biomechanics and metabolic rates while subjects ride using three shorter crank arm lengths (CALs) for the AL in decrements of 6.8 mm using a PAP beneath the prosthetic forefoot. On Day 2, the investigators will repeat the protocol of Day 1, but have riders use a PAP beneath the pylon for their AL.
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        The investigators will recruit 15 subjects with unilateral transtibial amputations from the
        VA Jewell Clinic, locally, and nationally.
      
Keywords: Rehabilitation