Optimizing Prosthetic and Bicycle Fit for Veterans With Transtibial Amputations

Study Overview
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Brief Summary
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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
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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.

Official Title
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Optimizing Prosthetic and Bicycle Fit for Veterans With Transtibial Amputations

Conditions
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Amputation

Intervention / Treatment
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* Other: Prosthetic/Bicycle Configuration


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: One amputation below the knee At least 1 year of experience using a prosthesis No current problems with the prosthesis or residual limb At or above a K3 Medicare Functional Classification Level Exclusion Criteria: Poor general health Difficulty with mobility Problems with balance or dizziness Current serious musculoskeletal injury besides that associated with an amputation Cardiovascular, pulmonary, or neurological disease or disorder

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Participants with Transtibial Amputation<br>The investigators will recruit participants with unilateral transtibial amputations who are at or above a K3 Medicare functional classification level (MFCL), and 18-55 years old. A K3 MFCL means that a person has the ability or potential for ambulation with variable cadence. A person at K3 MFCL is a typical community ambulator who has the ability to traverse most environmental barriers and may have vocational, therapeutic or exercise activity that demands prosthetic use beyond simple locomotion. | Other: Prosthetic/Bicycle Configuration<br>* 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.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Motion will be measured using 3D motion capture | The investigators will measure motion (rad) while participants bicycle using different prosthetic and bicycle configurations (pylon length, crank arm length, and pedal attachment position). | Through study completion, an average of 1 year | 
| Rates of oxygen consumption and carbon dioxide production will be measured using indirect calorimetry to calculate metabolic power | The investigators will measure and compare metabolic power from while participants bicycle using different prosthetic and bicycle configurations (pylon length, crank arm length, and pedal attachment position). | Through study completion, an average of 1 year | 
| comfort/pain will be measured with a Visual Analog Scale (VAS) | The investigators will measure and compare comfort/pain with a questionnaire that has a range of 0-10 that indicates no pain to the worst pain, respectively, after participants bicycle using each different prosthetic and bicycle configuration (pylon length, crank arm length, and pedal attachment position). | Through study completion, an average of 1 year | 
| Forces will be measured using force-measuring pedals | The investigators will simultaneously measure forces (N) while participants bicycle using different prosthetic and bicycle configurations (pylon length, crank arm length, and pedal attachment position). | Through study completion, an average of 1 year | 
| Muscle Activity will be measured using electromyography | The investigators will measure muscle activity (v) while participants bicycle using different prosthetic and bicycle configurations (pylon length, crank arm length, and pedal attachment position). | Through study completion, an average of 1 year | 
| comfort/satisfaction will be measured with a modified Prosthesis Evaluation Questionnaire (PEQ) | The investigators will measure and compare comfort/satisfaction with a questionnaire that has a series of questions that have a range of 0-10 that indicates worst to best, respectively, after participants bicycle using each different prosthetic and bicycle configuration (pylon length, crank arm length, and pedal attachment position). | Through study completion, an average of 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Rehabilitation