Optimizing Prosthetic and Bicycle Fit for Veterans With Transtibial Amputations
Conditions: Amputation
Sponsor: VA Office of Research and Development

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w 
COMIRB Protocol 
COLORADO MULTIPLE INSTITUTIONAL REVIEW BOARD 
CAMPUS BOX F-490    TELEPHONE:  303-724-1055  Fax:  303-724-0990 
 
 
 
Protocol #: 18-2783 
Project Title: Optimizing Prosthetic and Bicycle Fit for Veterans with Transtibial Amputations 
 
 
Principal Investigator: Alena Grabowski 
Version Date: 2/4/19  
 
 
 
 
  
 
I. Hypotheses and Specific Aims:   
 
The purpose of the research study is to challenge the state-of-the-science by developing 
evidence-based prosthetic and bicycle fit guidelines that optimize the biomechanics (injury), 
metabolic costs (effort), efficiency (function), satisfaction, and comfort of Veterans with transtibial 
amputations (TTAs). Thus, the proposed research is highly relevant to the rehabilitation of 
Veterans with TTAs. Following a TTA, Veterans who wish to restore their physical function have 
limited options for exercise. For example, running while using a prosthesis may increase the risk of 
secondary injury due to asymmetric and high loading patterns. Low impact exercise such as 
bicycling could facilitate normative function after amputation by improving cardiovascular fitness, 
muscle strength, endurance, and quality of life without incurring the high loads typical for walking 
and running for Veterans with 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, to maximize comfort and improve adherence to exercise, Veterans with a TTA likely 
need to adapt the fit of their prosthesis and bicycle. Optimizing bicycling, as exercise, for Veterans 
with TTAs through changes in prosthetic and bicycle fit (i.e. pylon length (PL), pedal attachment 
position (PAP) beneath the prosthetic forefoot versus the pylon, and crank arm length (CAL)) would 
improve rehabilitation by minimizing injury risk and discomfort, and maximizing function, thus 
facilitating the return to an active lifestyle and/or active duty. We propose to vary PL, CAL, and PAP 
in Veterans with unilateral TTAs. Then, we will develop evidence-based guidelines that optimize 
prosthetic/bicycle fit for Veterans with TTAs. These guidelines will allow Veterans with TTAs to 
enhance their physical function and quality of life by using bicycling for exercise.] Moreover, 
evidence-based prosthetic/bicycle fit guidelines will allow clinicians to more effectively fit Veterans 
with lower extremity amputations to bicycles, leading to shorter appointment times and fewer 
revisits due to enhanced function and reduced comorbidities.  
 
Specific Aim 1. We will 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 (AL) on bicycling biomechanics, metabolic cost, and comfort/satisfaction. Hypothesis 
1. A taller PL and shorter CAL for the AL compared to the unaffected leg (UL) and 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. Veterans with unilateral TTAs will ride a stationary 
bicycle ergometer at a fixed power output (1.5 W/kg) and complete a series of experimental trials 
over 2 days. On Day 1, we will perform a custom bike fit for each subject according to a protocol 
developed by Retül for non-amputees (Specialized Bicycle Components Inc., Boulder, CO). When 
fitting riders with TTAs, we will adjust the PL in combination with the socket and prosthetic foot of 
the AL to match the shank and foot length of the UL. Using this protocol, we will systematically vary 
saddle height and fore-aft position, handlebar vertical and fore-aft position, and alter cleat 
placement within the shoe for a forefoot PAP, using a conventional CAL of 172 mm. Then, we will 
measure the biomechanics (motion, forces, and muscle activity) and metabolic rates while subjects 
ride using the initial fit and three taller PLs for the AL in increments of 6.8 mm using a PAP beneath 
the prosthetic forefoot. Then, using the optimal (most efficient) PL, we will measure the 
biomechanics and metabolic rates while subjects ride using three shorter CALs for the AL in 

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decrements of 6.8 mm using a PAP beneath the prosthetic forefoot. On Day 2, we will repeat the 
protocol of Day 1, but have riders use a PAP beneath the pylon for their AL. We will randomize the 
order of days and trials within a day. [Because a prosthetic foot cannot flex and extend in a manner 
similar to the biological ankle, shortening CAL for the AL compared to the UL will reduce the 
geometric asymmetries between the AL and UL in bicyclists with a TTA. Childers and Kogler 
estimated that the UL shank and foot have 19.8 mm of displacement throughout the pedal stroke. 
Moreover, previous studies found differences in biomechanics and metabolic costs during bicycling 
based on CAL changes of 7.5-15 mm. Thus, we elected to measure the effects of four different 
CALs within a 19.8 mm range (0 mm, -6.6 mm, -13.2 mm, -19.8 mm) to establish how different 
prosthetic/bicycle configurations affect biomechanics and metabolic costs across CAL changes. To 
our knowledge, previous studies have not assessed the effects of changing PL. Thus, we chose to 
vary PL by the same magnitudes as CAL. We chose to increase PL and decrease CAL because if 
we lowered PL or increased CAL this would require us to lower the seat height for subjects to reach 
the bottom pedal position with their AL. 
 
Specific Aim 2. We will synthesize and disseminate our findings from Specific Aim 1 into 
practical, evidence-based quantitative prosthetic/bicycle fit guidelines for Veterans with TTAs 
through a multiple regression and principal component analysis. These analyses will take into 
consideration the body mass, femur lengths, and UL shank and foot dimensions. We will 
disseminate our guidelines to prosthetists and clinicians in peer-reviewed public-access journals 
and through conferences/seminars. 
 
II. Background and Significance:  
 
Healthcare costs in the United States (US) now exceed $3.2 trillion per year and many of the 
healthcare conditions at the root of these costs, such as Type 2 diabetes, are preventable through 
exercise. Due in large part to the prevalence of diabetes and recent military conflicts, there are over 
one million people in the United States who have a lower extremity amputation [1] and this number 
continues to grow. The incidence of diabetes is much greater in Veterans compared to the civilian 
population [2]; nearly one million Department of Veterans Affairs (VA) patients (1 of 5 patients) 
have diabetes. Over 25% of Veterans with an amputation attributable to vascular disease/diabetes 
will need an additional amputation [3]. It is projected that the number of people with diabetes who 
are living with limb loss will nearly triple and that the prevalence of limb loss will more than double 
by the year 2050 [4]. In addition, recent military conflicts such as Operation Iraqi Freedom (OIF) 
and Operation Enduring Freedom (OEF) have accounted for more than 1800 major limb 
amputations [5]. Due to functional impairments resulting from a lower extremity amputation, it is 
extremely important to advance rehabilitation practices that optimize the use of leg prostheses and 
increase exercise adherence so that Veterans and Service members with TTAs can regain the 
greatest possible level of health, function, and physical activity.  
 
Due in part to the increased prevalence of amputations in Veterans and Service members, the 
Department of Defense (DoD) and VA Rehabilitation Directive has put forth an initiative that aims to 
dramatically improve and restore function in wounded Service members so that they have the 
choice to return to active duty or productive civilian employment. Our proposed research and 
development of optimized prosthetic/bicycle fit guidelines will enable VA prosthetists to improve 
rehabilitation, physical activity level, injury risk, and comfort of Veterans following amputation, thus 
helping to fulfill this initiative and having high potential impact. Our research addresses the 
Prosthetics and Limb Loss focus area within the Rehabilitation Research and Development service. 
This focus area serves to integrate advances in technology and rehabilitation to improve the lives 
of Veterans with an amputation. The utilization of evidence-based prosthetic/bicycle fit guidelines 
that optimize comfort, exercise adherence, and function will directly benefit Veterans with an 
amputation and the VA. More effective and optimized prosthetic and bicycle fitting will result in 
greater power output symmetry, reduced metabolic costs and injury risk, improved efficiency, and 
increased comfort. We aim to provide the best rehabilitation outcomes data regarding prosthetic 
devices and related clinical interventions. 
 
Only 32-37% of people with TTAs engage in enough vigorous physical activity to elicit health 
benefits compared to 60% of non-amputees [6, 7]. Engagement in physical activity following an 
amputation is much lower than that of pre-amputation levels, and there are more barriers than 

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motivations for adopting and maintaining a physically active lifestyle in people with TTAs [6]. 
Generally, people with TTAs who return to recreational or sports activities choose to participate in 
less strenuous activities where a prosthesis is not required or the person is not functionally 
dependent on it. The barriers to engaging in physical activity include pain and physical limitations 
[6, 7]. Throughout rehabilitation, it has been suggested that clinicians and prosthetists should 
repeatedly encourage people with TTAs to stay/become physically active and provide information 
about strategies to reduce environmental barriers to sports participation, which could help people 
using assistive devices to overcome these barriers [8]. An optimal prosthetic/bicycle fit would 
reduce pain, physical limitations, and environmental barriers to exercise and could thus promote 
physical activity in Veterans with TTAs. Low impact aerobic exercise such as bicycling could 
facilitate normative function after amputation by improving cardiovascular fitness, muscle strength, 
endurance, and quality of life for Veterans with TTAs without incurring the high joint and tissue 
loads inherent in walking and running [9]. Bicycling for 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, a previous study estimated that only 11.5% of Veterans with TTAs use bicycling for 
exercise [7]. It is likely that bike and socket discomfort/pain and the increased potential for 
secondary musculoskeletal injury due to the lack of a proper bike fit discourage Veterans with TTAs 
from using bicycling for rehabilitation and exercise.  
 
Riding a bicycle with a TTA presents novel challenges compared to non-amputees. People 
with TTAs lack the muscles that plantarflex and dorsiflex the ankle joint to assist them in the 
pedaling motion of bicycling. These muscles act to stabilize the ankle and transfer force and energy 
to and from the pedal [9]. Bicyclists with TTAs have increased muscle activity variability in the two-
joint muscles of both legs and a longer duration of gastrocnemius activity in the unaffected leg (UL) 
compared to non-amputees [9]. Although the role of the ankle in bicycling is disputed, research has 
shown that the ankle position throughout the pedal cycle influences the application of mechanical 
power generated by the leg [10]. Pierson-Carey et al. [10] immobilized the ankle in non-amputees 
and found that during the down-stroke of the pedaling cycle, power output decreased compared to 
a fully mobile biological ankle joint. The application of force on each bicycle pedal influences 
mechanical power production, and therefore affects overall efficiency. Thus, optimizing PL, PAP, 
and/or CAL would improve mechanical power output symmetry and efficiency in individuals with 
TTAs during bicycling.  
 
Research that examines the underlying changes in biomechanics and metabolic costs that are 
elicited by people with TTAs when bicycling with different prosthetic/bicycle configurations would 
facilitate improved rehabilitation [9] and exercise adherence. Changes in body positioning due to 
changes in PL, CAL, and PAP likely affect the overall function, comfort, and injury risk of bicyclists, 
but the effects of these changes are complex and likely more complicated due to different limb 
geometry in bicyclists with TTAs [9]. The asymmetric structural differences between the legs of 
bicyclists with a TTA result in dramatically asymmetric torque and mechanical work during 
bicycling; mechanical work asymmetry can be up to 7x greater in bicyclists with a TTA compared to 
non-amputees [9]. Presumably, the magnitude of force asymmetry between the AL and UL of 
people with unilateral TTAs is influenced by leg length discrepancies and the loss of the muscles 
that act across the ankle joint. To our knowledge, no previous research has systematically varied 
PL and determined the effects on bicycling biomechanics and performance. Because a person with 
a TTA does not have a functional ankle joint, the PL combined with prosthetic foot build height may 
need to be taller than the height of the foot and shank of the UL to improve mechanical power 
symmetry and lower metabolic cost. Further, despite previous research, it remains unclear how 
alterations to a bicycle’s CALs affect the efficiency of people without and with TTAs [9]. When 
manipulating CALs for both legs of non-amputee cyclists, Morris & Londeree [11] found that each 
individual had a specific CAL that resulted in the greatest efficiency. However, with a relatively 
small sample size (n=6), they were unable to determine any relationships between the rider’s leg 
lengths and optimal CALs. Koutny et al. [12] investigated the effects of using three different CALs 
(160, 167.5, and 175 mm) on one high-caliber cyclist with a TTA and found that at a fixed 
mechanical power output, the rider’s leg muscle activity was minimized with the medium CALs 
(167.5mm), but the average torque applied to the cranks was unchanged across CALs. It is unclear 

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whether Koutny et al. manipulated CALs for both legs or just 
changed the CAL for the affected leg (AL). Regardless, 
reduced muscle activity suggests a lower metabolic cost and 
thus improved efficiency during bicycling. Childers and Kogler 
[13] compared the knee and hip joint kinematics and kinetics 
of 8 cyclists with TTAs with CALs of 172 mm for each leg 
compared to a CAL of 172 mm for the UL and a CAL of 162 
mm for the AL. With asymmetric CALs, knee and hip joint 
angles and range of motion were more symmetric between 
legs, but joint kinetics (torque and work) did not change. They 
suggest that a CAL of 160 mm for the AL would be 
advantageous for joint angle and range of motion symmetry. 
However, it is not clear if Childers and Kogler [13] matched 
the AL height of the pylon and the prosthetic foot to the UL 
height of the shank and biological foot. Shortening the CAL 
for the AL could reduce the geometric asymmetry between 
legs and thus result in more symmetric knee and hip joint 
angles.] A pilot study (n=3) by Childers et al. [9] found that a 
15 mm shorter CAL for the AL versus UL may improve the 
force symmetry of people with TTAs and thus improve their 
power output symmetry. They reported that shortening the 
CAL for the AL versus UL reduced mechanical work 
asymmetry by 53% [9]. Further, with a shortened CAL on the 
AL compared to UL, riders reported improved comfort [9]. 
[Previous studies that varied the anterior-posterior position of 
the bicycle cleat (PAP) found no effects on metabolic costs 
for non-amputees, but did find a reduction in gastrocnemius, 
soleus, and tibialis anterior muscle activations with a forefoot 
position compared to a heel placement. Childers et al. [9] 
suggest that the effective prosthetic length, the distance from 
the knee center to the pedal spindle, should be equivalent 
between legs in cyclists with unilateral TTAs to minimize 
kinematic asymmetries. However, no studies to date have 
determined the optimal PAP or calculated the optimal 
effective prosthetic length.   
 
 Moreover, it is unclear how changes in each prosthetic and bicycle configuration, such as PL, 
PAP beneath the prosthetic forefoot versus the pylon, and CAL (Fig. 1) affect the biomechanics, 
metabolic cost, and comfort/satisfaction of Veterans with TTAs. Thus, we will quantify the effects of 
systematic changes in PL, PAP, and CAL on the bicycling performance of Veterans with unilateral 
TTAs to develop novel evidence-based guidelines that optimize prosthetic and bicycle fit. The 
proposed analysis is innovative in that we will assess and optimize the effects of each geometrical 
change in the same person and use the overall results to develop guidelines for bicycle/prosthetic 
fit. Further, we will examine the underlying mechanisms, such as changes in joint kinematics and 
kinetics, and muscle activity magnitude and timing that elicit these effects to determine the unique 
adaptations made by bicyclists with TTAs. Optimized prosthetic and bicycle fit guidelines will allow 
Veterans with TTAs to ride longer with less effort, pain/discomfort, and injury risk, which would lead 
to improved rehabilitation and quality of life. Reducing the metabolic cost required for bicycling is 
clinically significant because an excessive sense of effort and fatigue discourages physical activity 
[14]. The prosthesis/bike fit guidelines resulting from our research will also determine the 
configuration that maximizes symmetry between legs, which could reduce injury risk and pain, and 
maximize function through improved mechanical power output and efficiency. Moreover, evidence-
based prosthetic/bicycle configuration guidelines will allow clinicians to more effectively treat 
Veterans with TTAs, leading to shorter appointment times and fewer revisits due to enhanced 
function and reduced comorbidities. 
 
Figure 1. A pylon connects the 
socket of the affected leg of a 
cyclist with a transtibial 
amputation to the prosthetic 
foot, which attaches to the 
pedal. The crank arm links the 
pedal to the chain ring, allowing 
power transmission to the rear 
wheel. Adjustments to pylon 
length (PL), pedal attachment 
position (PAP) and crank arm 
length (CAL) likely affect 
mechanical power output, 
metabolic cost and 
comfort/satisfaction.  

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III. Preliminary Studies/Progress Report:   
 
Our proposal represents a potentially high-risk 
project because we lack substantial preliminary 
data. However, we believe that the project is 
innovative and feasible. To support the feasibility 
of the project, we measured the average 
mechanical power output from both legs and each 
leg when one subject with a TTA rode on a cycle 
ergometer, which had fixed CALs (172 mm) 
(Table 1). We measured mechanical power output 
using PowerTap P1 pedals (PowerTap, Madison, 
WI). Across overall mechanical power outputs of 
50-175 W, the AL provided ~40%, while the UL 
provided ~60% of the overall mechanical power 
output. Thus, the development of optimal 
prosthetic/bicycle configuration guidelines could 
improve biomechanical symmetry and maximize 
function in Veterans with TTAs, yet bicycles have not been effectively utilized in clinical settings. 
Bicycling as a form of exercise has been shown to greatly improve overall fitness, reduce obesity, 
and prevent cardiovascular health problems in non-amputees [15], yet <12% of Veterans with 
TTAs use bicycling for exercise. By systematically altering PL, PAP, and CAL, we expect to 
optimize function and comfort by reducing kinematic and kinetic asymmetries, reducing metabolic 
costs, and improving efficiency for Veterans with TTAs during bicycling. We expect that these 
improvements will increase the use of bicycling for exercise and thereby advance the rehabilitation 
and function of Veterans with TTAs.  
 
IV. Research Methods 
 
The proposed study will be a repeated-measures within-subjects design. This is a multi-site 
study, and the VA Eastern Colorado Healthcare System and University of Colorado Boulder will be 
participating. 
A.  Outcome Measure(s):   
 
During each trial, subjects will ride a stationary bicycle ergometer (Retül Müve, Specialized 
Bicycle Components Inc., Boulder, CO). Each trial will be 6 minutes long with at least 6 minutes 
rest between trials. At minutes 4 and 5, we will measure kinematics at 100 Hz, including joint 
angles, with a 10-camera 3D motion capture system (Vicon, Centennial, CO), kinetics at 1000 Hz, 
including mechanical power output, with motion capture and force-measuring pedals (Sensix, 
Poitiers, France) and muscle activity at 1000 Hz using electromyography (Noraxon, Scottsdale, AZ) 
for approximately 30 seconds. The key muscles that influence bicycling are the vastus lateralis, 
rectus femoris, biceps femoris, gluteus medius, gluteus maximus, tibilais anterior, soleus, and 
gastrocnemius [9]; thus we will calculate activation magnitudes and durations for these muscles 
during each trial, when possible. We will analyze these data with Visual 3D software (C-Motion, 
Germantown, MD) using a standard anatomical model and a custom software program (Matlab, 
Mathworks, Natick, MA). We will measure rates of oxygen consumption and carbon dioxide 
production at standard temperature and pressure dry (STPD) throughout each trial using indirect 
calorimetry (ParvoMedics TrueOne 2400, Sandy, UT). We will calculate average steady-state 
metabolic power (W) from minutes 3.5-5.5 of each trial using a standard equation [16]. In our 
experience, a 6-minute trial duration is sufficient for subjects to reach steady-state metabolic rates. 
We will adjust trial length as needed if 6 minutes is not sufficient. We will calculate efficiency by 
dividing the mechanical power (1.5 W/kg) by the average metabolic power in W/kg. We will 
calculate the degree of mechanical power output symmetry between legs for each configuration 
using the symmetry index (SI) as a percentage: 
, where MechP 
is the mechanical power for the UL and AL of subjects with a TTA. SI values closest to zero are the 
most symmetric. After each trial, we will ask all subjects to rate their comfort/pain with a Visual 
Analog Scale (VAS), and subjects with TTAs to rate their comfort/satisfaction with a modified 
Table 1. Total, affected leg (AL) and 
unaffected leg (UL) mechanical power 
(Watts) and cadence from the Lode bicycle 
ergometer for an athlete with a unilateral 
transtibial amputation. Each stage was 4 min 
and we averaged data from the last 3 min. 
Total  
(W) 
Cadence 
(RPM) 
AL  
(W) 
UL  
(W) 
50 
78.5 
18.37 
31.63 
75 
78.0 
28.54 
46.46 
100 
78.1 
40.91 
59.09 
125 
79.0 
49.99 
75.01 
150 
80.0 
63.28 
86.72 
175 
80.8 
75.29 
99.71 

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Prosthesis Evaluation Questionnaire (PEQ). We will use repeated measures analysis of variance 
(ANOVAs) (significance at <0.05) with Bonferroni corrections as needed for multiple comparisons 
to compare data between groups and between legs and determine the optimal PL/PAP/CAL 
combination (JMPIN, SAS Institute, Cary, NC). We will analyze results from Specific Aim 1 using 
linear mixed models. We will use a multiple regression and/or principal component analysis to 
develop optimal prosthetic/bicycle fit guidelines for Veterans with TTAs in Specific Aim 2.  
 
Description of Population to be Enrolled:   
 
We will recruit 15 Veterans with unilateral TTAs who are at or above a K3 Medicare functional 
classification level (MFCL), and who are 18-55 years old from the VA Jewell Clinic, locally, and 
nationally. Subjects will give informed consent prior to participation. 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. Subjects will have no known neurological disease or disorder, and will have no 
musculoskeletal injuries beyond an amputation. These inclusion/exclusion criteria will minimize any 
potential confounding variables, thereby increasing the internal validity of the proposed studies. 
Any person matching the inclusion criteria of the study, regardless of race or gender, will be 
recruited to participate. 
 
Women and/or minorities will be included in the proposed study. Anyone matching the 
inclusion criteria of the study, regardless of race, sex, or ethnicity will be recruited to participate. 
 
B. Study Design and Research Methods   
 
Before participants are enrolled in each study, we will complete a pre-screening form and each 
participant will be asked to give informed written consent. We will ensure that all participants 
understand the consent form and protocol prior to participation.  
 
Subjects will be asked to complete two experimental sessions at the VA ECHCS/University of 
Colorado Applied Biomechanics Lab; each session on a separate day at the same time of day, and 
requiring approximately 2 hours of time. Subjects will be asked to ride a stationary bicycle 
ergometer (Retül Müve, Specialized Bicycle Components Inc., Boulder, CO) at a fixed power 
output (1.5 W/kg) and complete a series of experimental trials over two days. On each day, we will 
measure each subject’s height, weight, and limb segment lengths. Then, we will place reflective 
markers on his/her legs and torso using double-sided tape. These markers will allow us to track 
his/her body position using our motion capture system. We will also record the forces subjects 
exert on each pedal using force-measuring pedals. Further, we will measure each subject’s leg 
muscle activity using wireless electrodes that will be placed over his/her muscles using double-
sided tape. Finally, we will measure each subject’s metabolic rates from the air that he/she 
breathes out into a mouthpiece. Immediately after each trial, we will ask subjects to rate their 
satisfaction using a Visual Analog Scale and comfort, fit, effort, etc. with a questionnaire.  
 
On Day 1, we will perform a custom bike fit for each subject according to a protocol developed 
by Retül for non-amputees (Specialized Bicycle Components Inc., Boulder, CO). Using this 
protocol, we will systematically vary saddle height and fore-aft position, handlebar vertical and fore-
aft position, and alter cleat placement within the shoe for a prosthetic forefoot pedal attachment 
position, using a conventional crank arm length of 172 mm. Then, we will measure the 
biomechanics and metabolic rates while subjects ride using the initial fit and three taller pylon 
lengths for their affected leg in increments of 6.8 mm using a typical pedal attachment position 
beneath the forefoot. Then, using the optimal (most efficient) pylon length, we will measure the 
biomechanics and metabolic rates while subjects ride using three shorter crank arm lengths for 
their affected leg in decrements of 6.8 mm using a typical pedal attachment position beneath the 
prosthetic forefoot.  
 
On Day 2, we will repeat the protocol of Day 1, but have subjects use a pedal attachment 
position beneath the pylon for their affected leg. We will randomize the order of days and trials 
within a day.  
 
 

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D.   Description, Risks and Justification of Procedures and Data Collection Tools: 
 
We propose to study healthy people who are familiar with using a prosthesis because this 
choice minimizes any potential confounding factors associated with novel prosthetic use. Bicycling 
requires moderate exercise intensity, yet poses no more than minimal cardiac risk for this 
population. We will restrict our patient age range to comply with the American College of Sports 
Medicine guidelines. The American College of Sports Medicine (ACSM) Guidelines for Exercise 
Testing and Prescription (Ninth edition, 2014) classify individuals of any age as having low or 
moderate risk to participate in an exercise program if they present no more than two of the 
following risk factors: males age ≥ 45 yrs, females age ≥ 55 yrs, first degree family history of 
coronary artery disease, cigarette smoking, sedentary lifestyle, obesity, hypertension, dyslipidemia 
(high cholesterol), and pre-diabetes. These guidelines further recommend that a medical exam and 
diagnostic exercise testing are not warranted prior to beginning a moderate exercise program for 
individuals at low to moderate risk. We are being conservative by including patients under 55 years 
of age (i.e. before their 55th birthday) who do not have any of the other risk factors listed above.  
 
We will comply with Good Clinical Practices (GCPs) by upholding standards for the design, 
conduct, performance, monitoring, auditing, recording, analysis and reporting of our clinical studies, 
and by protecting the rights, safety, and well-being of human subjects. We will assure the quality, 
reliability, and integrity of data collected. We will maintain and monitor GCPs by obtaining 
Institutional Review Board (IRB)-approval, requiring informed consent, having a data-monitoring 
plan, reporting Adverse or Serious Adverse Events, having proper documentation, and validating 
our data collection and reporting procedures. 
 
Foreseeable risks:  
1. There is a potential risk of physical discomfort from wearing any type of prosthesis.  
2. The adhesive used for motion analysis markers and electrodes may produce slight discomfort. 
3. The metabolic analysis mouthpiece and nose clip may produce slight discomfort.  
4. Confidential information about participants will be collected as part of this study; therefore, there 
is a risk of disclosure. 
 
Risk management (corresponds directly to the Foreseeable risks listed above): 
1. If you become fatigued, you may ask to rest or stop the study at any time. 
2. Before participating in a study, you will be asked if you have any adhesive allergies and if you 
do, the reflective markers can be placed over tight-fitting clothing. 
3. You may ask to remove the mouthpiece and nose clip, rest or stop at any time.  
4. Significant efforts will be made to guard against the disclosure of confidential information. All 
data collected will be de-identified so that your identity is protected; however, the data collected 
poses no apparent risk to your privacy. We will implement a data and safety-monitoring plan to 
ensure your privacy. To de-identify your data, you will be given a unique code, and only the 
research team will have access to the key (linking the code to participant identifiers), which will be 
kept in a locked cabinet in a locked office. The key will be destroyed upon study completion.  
    
E.   Potential Scientific Problems:   
 
Adjustments to PL, PAP, and CAL may not be significantly different from the standard 
prosthetic/bicycle configuration. In the unlikely event that we find the optimal configuration to be the 
same as the standard configuration, we will be more confident in the typical recommendations for 
bicycling and may not need to develop guidelines for optimizing efficiency and comfort. If we find 
this to be true, we will evaluate how robust this finding is across participants. Within our protocol, 
we will ask 15 patients with TTAs to complete a VAS and modified PEQ. We predict that use of 
different PLs, PAPs, and CALs will affect VAS and PEQ scores. We calculated a statistical power 
of >0.44 to detect a 10% difference in PEQ scores based on 15 participants and the largest 
standard deviations found in previous studies using the PEQ [23]. Therefore, we may not have 
adequate statistical power to detect a difference in comfort and fit.  
 
 
 

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F.   Data Analysis Plan:   
We predict that different PLs, PAPs, and CALs will affect biomechanics, metabolic costs, and 
comfort/satisfaction. We calculated effect sizes [17] >0.86, >0.995, 0.97, and >0.44 to detect 10% 
differences in efficiency (mechanical power/metabolic power), knee and hip joint range of motion, 
mechanical work output symmetry, and PEQ scores, respectively, based on 15 participants, a 
repeated measures design, α=0.05, and standard deviations found in previous studies [11, 13, 18, 
19]. Thus, we feel we have an adequate sample size to detect biomechanical and metabolic 
differences in our proposed studies, but may not have adequate power to detect differences in 
PEQ scores. 
 
G.  Summarize Knowledge to be Gained:   
 
The proposed research is highly relevant to and will benefit Veterans with transtibial 
amputations (TTAs). The goal of our research is to challenge the state-of-the-science by 
developing evidence-based prosthetic and bicycle fit guidelines that optimize the biomechanics, 
metabolic costs, efficiency and comfort/satisfaction for Veterans with TTAs. Optimizing these 
parameters through changes in prosthetic and bicycle configurations (i.e. pylon length (PL), pedal 
attachment position (PAP) beneath the forefoot versus the pylon, and crank arm length (CAL)) will 
improve rehabilitation and benefit Veterans with TTAs by minimizing injury risk and pain/discomfort, 
and maximizing physical activity and function; thus facilitating their return to an active healthy 
lifestyle and/or active duty. 
 
 H. References: 
1. 
Ziegler-Graham, K., et al., Estimating the prevalence of limb loss in the United States: 
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