Microprocessor Knee Versus Mechanical Knee: Impact on Functional Outcomes in Dysvascular Transfemoral Amputees
Phase: NA
Conditions: Transfemoral Amputation, Unilateral Traumatic Amputation of Leg at or Above Knee
Sponsor: Shirley Ryan AbilityLab

Page 1 of 12
1) Protocol Information
Title: Microprocessor knee vs. mechanical knee: Impact on functional outcomes in 
dysvascular transfemoral amputees.
 May 8th 2013.
Principle Investigator
Arun Jayaraman, PT. PhD
Director, Rehabilitation Technologies & Outcomes Lab.
The Rehabilitation Institute of Chicago.
345 E Superior Room, Chicago IL 60611
312-238-6875    Phone
312-238-2081      Fax
a-jayaraman@northwestern.edu
Study Information
Type of Research: Biomedical Research
2) Background/ Key Questions:
 
In older adults, poor circulation in the lower extremities or dysvascular disease 
can lead to serious health complications. In addition, these individuals also suffer from 
serious co-morbidities like diabetes and coronary or cerebrovascular disease. Circulatory 
dysfunction or dysvascular disease is the major cause for amputations in the United 
States 
(www.amputee-coalition.orf/fact_sheet/amp_stats_cause.html). 
Increasing 
sedentary lifestyles have lead to increased rates of diabetes which has significantly 
contributed to an increased number of amputations in recent years. The risk of 
amputation in a diabetic individual is 25 times higher than in the non-diabetic population 
(Witsø & Rønningen 2001). 
The level of amputation that is appropriate for an individual depends on the extent 
of damage to his/her tissues. Common amputations of the lower extremities in the 
dysvascular population include the transtibial and transfemoral amputations. The 
individual having a transtibial or below knee amputation, will be fitted with a prosthetic 
foot to assist with functional ambulation, while a person with a transfemoral amputation 
will require both a prosthetic foot and knee for ambulatory purposes. Currently 
dysvascular amputees are given prostheses based on the goal of returning them to a basic 
level of function focused primarily on stability. They are considered lower functioning 
walkers and are expected to use a slow and constant walking speed to ambulate around 
their homes and are not considered traditional community ambulators. Therefore, they are 
traditionally given standard mechanical knees which are considered safe, as they provide 
the ability for only simple single speed house-hold tasks. While this criterion does return 
the patient to function for basic Activities of Daily Living (ADLs) and walking at a single 
cadence, it does not empower the patient to counteract the previously existing co-
morbidities. Dysvascular amputees tend to be less active predisposing them to a more 
sedentary lifestyle and exacerbating their risk factors. Their prostheses make them energy 
inefficient and use more energy for ADLs and functional walking. This causes early onset 
of fatigue, induces anxiety and fear of falling. Further, they are often depressed, lose 

Page 2 of 12
motivation and curtail their community interaction. This raises the question if dysvascular 
amputees are further functionally limited by the prostheses traditionally given to them.
More recently, technology has been used to assist with return to function in the 
amputee population. Microprocessor (MP) controlled knees are among the technological 
innovations applied to prostheses to not only return amputees to a basic function, but also 
with a view to return them to their highest possible function. Over the years, clinical use 
has shown that traditional knees provide the ability to complete ADLs and basic 
functions like sit – stand. However, activities like negotiating stairs/steps, walking on 
uneven ground and self-correction during tripping; functions which reintegrate amputees 
into unlimited community ambulation and social reintegration require prosthetics which 
advanced functionality. The Otto Bock C-leg is a MP knee that allows the patient a 
greater level of control in swing and stance phases of gait. This enables the TF amputee 
to adjust the requirements of gait during dynamic walking like changing the speed of 
walking, going up and down stairs and inclines, walking on grass and uneven surfaces 
and crossing an obstacle. The C-leg has been traditionally given to patients who begin 
post-amputation rehabilitation at a higher level, but are more expensive than traditionally 
mechanical knees. In the contrary however, a European study that defined health 
outcomes in terms of quality-adjusted life year (QALY), indicated that the C-leg showed 
a QALY gain of €3218 per patient (Brodtkorb et al 2008), makes it still financial viable 
keeping it mind its price tag..  The purpose of this study is to compare the traditional 
mechanical knee to the microprocessor knee (C-leg) in the dysvascular population. The 
study will specifically evaluate the potential of microprocessor knees to improve the 
quality of life in dysvascular transfemoral amputees. This includes identifying if the C-
leg can increase the activity level to be classified at a higher level by the Medicare 
classification from K2 (lower level ambulators) to K3 (more proficient ambulators), 
along with increasing their social interaction in the community. 
3) Hypotheses & Research Objectives and Purpose:
Central Hypothesis: We hypothesize that giving microprocessor knees (C-leg®), will 
significantly increase everyday function, social interaction, and quality of life in K2 
Dysvascular subjects with transfemoral amputation in comparison to a standard 
mechanical knee (both FDA Class II exempt devices). The study will primarily aim to 
study the impact of the C-leg on ADLs and community interaction ADLs and function:
Hypothesis 1: We hypothesize that the C-leg will significantly increase every day 
physical activity measured using GPS tracked activity in K2 Dysvascular subjects in 
comparison to a mechanical knee.
Hypothesis 2:  We hypothesize that the C-leg will significantly increase functional 
mobility in K2 Dysvascular subjects compared to a mechanical knee: increased stepping 
measured using Step Activity Monitor (SAM), increased gait speed and distance 
measured by Six Minute Walk Test (6MWT), increased mobility measured by the 
Amputee Mobility Predictor (AMP).
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 3 of 12
Hypothesis 3: We hypothesize that the C-leg will significantly increase community 
mobility measured using GPS technology in K2 Dysvascular subjects in comparison to a 
mechanical knee.
Sub -hypothesis 
3a: That C-leg will improve ambulation distance vs. mechanical knee
3b: That C-leg will improve time out of home vs. mechanical knee
3c: That C-leg will improve ability to use public transport vs. mechanical knee
3d: That C-leg will decrease gait aid vs. mechanical knee
Hypothesis 4: We hypothesize that the C-leg will significantly improve social integration 
as measured by CPI (Community Participation Indicators)  in K2 Dysvascular subjects in 
comparison to mechanical knee.
Hypothesis 5: We hypothesize that the C-leg will significantly improve both static and 
dynamic balance as measured by Single Leg Stance (SLS), Timed Up and Go (TUG), 
BERG Balance Scale (BBS), Four Square Step test (FSST) and Dual task TUG tests  in 
K2 Dysvascular subjects compared to a mechanical knee.
Hypothesis 6: We hypothesize that the C-leg will significantly improve self-reported 
measures in K2 Dysvascular subjects in comparison to mechanical knee.reduced falls 
measured by The Falls Efficacy Scale (FES), improved prosthesis use measured by The 
Prosthesis Evaluation Questionnaire (PEQ)
  
This study will be conducted at the Rehabilitation Institute of Chicago, 345 E. Superior 
St, Chicago, IL 60611.
 4) Research Methods:
Study Design: 
The study will have a randomized, repeated measures design. Due to the high rate of 
attrition we will randomize a total of 40 subjects, 20 into each of the groups below.
Group I
Mech 
Knee+Old 
Foot
C-leg + New 
Foot
C-Leg + New 
Foot
Mech knee + 
New Foot
Mech knee + 
New Foot
>6 
months 
post 
TF  
prosthetic 
fitting
Acclimation
Assessment
Acclimation
Assessment
Duration
3 months
3 months
3 months
3 months
Data 
Collection 
Monthly
Monthly
Monthly
Monthly
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 4 of 12
Group II
Mech 
Knee+Old 
Foot
Mech Knee + 
New Foot
Mech 
Knee 
+New Foot
C-Leg+ New 
Foot
C-Leg+ New 
Foot
>6 
months 
post 
TF  
prosthetic 
fitting
Acclimation
Assessment
Acclimation
Assessment
Duration
3 months
3 months
3 months
3 months
Data 
Collection 
Monthly
Monthly
Monthly
Monthly
All measures will be administered and data collected under the supervision of a licensed 
physical therapist.
I.
Assess and compare mobility in TF amputees: 
a.
To quantify community ambulation including time spent out of the home, 
use of public transport, GPS technology will be used. Subjects will be 
required to wear a GPS monitor on their belts during the day. This will 
track their activities in their homes and in the community.
b. To assess functional mobility the Amputee Mobility Predictor will be 
used. A standardized sequence of mobility tests with the prosthesis will be 
administered on the first pre-acclimation session. The patient will be 
scored out of 39.
c.
To quantify fall risk and functional mobility the Timed Up and Go (TUG) 
test will be used. TUG is the time taken for the subject to get up from 
chair, walk 3 meters and sits down; measured in seconds.
d. To objectify the amount of steps in ADLs and functional mobility the Step 
Activity Monitor will be used. The subject will be given a monitor that 
he/she will have to wear around his/her ankle. This will record the number 
of steps.
e.
To determine community and social participation, the Community 
Participation Indicators questionnaire will be used. It is a valid, new 
generation of self-report outcome measure for community participation. It 
will take 15-30 minutes to complete and will be administered in room 
1771.
II. Assess and compare gait distance and speed: 
a.
To determine maximum gait distance while using the prosthesis, distance 
and perception ratings will be recorded during the 6 minute walk test. 
Subjects will walk for 6 minutes with prosthesis with researcher walking 
alongside with walking wheel to determine distance walked in 6 minutes 
while recording their Rating of Perceived Exertion on the Borg Scale.
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 5 of 12
III. Compare the static and dynamic stability: 
a.
To assess balance during functional activities the BERG balance scale will 
be used. This is a performance based tool, scored 0-56.
b. To assess static balance, the single leg stance will be used. This will time 
in seconds, how long the subject can stand on one leg.
c.
To assess stepping and change of direction, the four square step test will 
be used. The subject will be required to walk in a sequence across canes 
arranged in four squares, timed in seconds.
d. To assess dynamic falls risk and multitasking ability, the Dual task TUG 
will be performed. The patient will be given a second motor task while 
performing the TUG (e.g. carrying a glass of water)
IV. Assess and compare patient perception and preference:
a.
To determine falls and near falls, subjects will fill out a self- reported Falls 
Efficacy scale (FES) 
b. To determine if cognition is a limitation the Mini-Mental State Exam 
(MMSE) will be administered.
c.
To determine prosthesis use and preference, the Prosthesis Evaluation 
Questionnaire (PEQ) will be given to the subject to fill out.
d. These questionnaires will take between 5-20 minutes each to fill out.
Data Collection and Analysis
Subjects will be screened and medical history and information relevant to why and when 
they received an amputation will be accessed from their medical records. Subjects will be 
explained the study design, procedures, tests, questionnaires and physical therapy visits 
asked to sign an informed consent prior to participating in the study. After subjects are 
randomized into two groups, they will be provided with a GPS device and a step activity 
monitor which will track their walking/mobility patterns at home and in the community 
for 4 weeks. When they return, over 1-2 visits, they will be assessed for a full battery of 
baseline outcome measures: six minute walk test (6 mwt), Amputee Mobility Predictor 
(AMP), Timed Up and GO (TUG), BERG balance test,. They will also be required to fill 
in self-report questionnaires for falls and the PEQ. They will then be fitted with the 
randomized prosthesis and new foot by a certified prosthetist. There will a period of 
acclimation for 3 months during which patients will be provided physical therapy with 
either the C-leg with a new foot or a mechanical leg with a new foot. Subjects will come 
for an average of two times a week for  physical therapy training. The pre-training visits 
will include 1 for informed consent and GPS, 1-2 for evaluation and an additional 1-2 for 
prosthetic fit. The training sessions will be a maximum of 14. There will also be 1-2 re-
assessment visits. This will be repeated for the other prosthesis. There will be a maximum 
total of up to 45 visits. Subjects will be compensated $40 per session for evaluation and 
assessments, prosthetic fittings and training sessions. This is the usual amount in similar 
studies and other studies at the Rehabilitation Institute of Chicago. The total 
compensation will be determined by the number of sessions that the subject completes 
while enrolled in the study. There will be 2 sessions allowed for a subject to be paid, even 
if they arrive but are unable to complete a session due to unscheduled issues (such as 
illness). However, if patients miss 3 or more consecutive visits, or experience a medical 
illness that may/may not require hospitalization, patients may have to be withdrawn from 
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 6 of 12
the study. Patients will be offered the additional service of adjustments for 
prosthesis/refining home exercise program in phone or in person, but they will not be 
compensated for these patient initiated services.
The training will focus on providing both groups 1) strength training for upper limbs, 
core and lower limbs, 2) functional training, e.g. sit – stand, gait training on level 
surfaces, community ambulation and 3) cardiovascular and endurance training. The 
following 3 months there will be an assessment period for that particular knee and foot 
combination. In the course of the assessment period, patients will come in at regular 
intervals for data collection for the AMP and the 6 mwt. During the last 2 weeks of the 
assessment, patients will be given GPS devices for tracking their mobility data. At the 
end of 6 months there will be a crossover where patients with the mechanical leg will 
receive a new C leg + new foot and patients with the C leg will receive a mechanical leg 
+ new foot. Once again, this will be followed by baseline testing, a period of 3 months 
acclimation with physical therapy sessions and a 3 month period of assessment where 
patients will come in for data collection. In the last 2 weeks, GPS data will be collected. 
The data collected will be analyzed for differences in outcome measures caused by the 
different prosthetic devices. 
During the data collection process and the training sessions, a licensed physical therapist 
will be present to provide supervision and monitoring of the patient’s vitals, signs and 
symptoms. During the sessions, subjects may be photographed or videotaped performing 
assessments, functional tasks, or exercising, with their consent. The photos and video 
recordings will not include the subjects face and if used for presentations or publications, 
will not identify the subject. The data collection and the training sessions will be 
terminated if the subjects expresses that he/she is unable/does not wish to participate. 
Subjects will be compensated $40 per session. Payment will be in cash or by ClinCard 
per session, at the end of each session.  RIC is moving away from using petty cash.  
During this transition period the subject may be paid in cash or by ClinCard. If a 
ClinCard is available when you come for the the study, you will be paid by card. If a 
ClinCard is not available, then you will receive cash payments.
If the subject is issued a ClinCard, which is a specially designed debit card for clinical 
research, the funds will be loaded as appropriate. When a visit is completed, funds will be 
approved and loaded onto the card. The funds will be available within 1 day after being 
loaded and can be used at the subject’s discretion. The subject will be issued one card for 
the duration of your participation. If your card is lost or stolen, please call (866) 952-
3795 or ask a coordinator for a replacement ClinCard.
Fees are incurred if used at an ATM (fees vary by location).  However, if the card is used 
for in-store or online purchases via credit or debit, or presented to a bank teller, there are 
no associated fees and no expiration date. 
If subjects wish to join RIC’s gym to exercise to increasing endurance and fitness, we 
will provide them membership (with an RIC physician signing membership form) to 
RIC’s Fitness Center and Sports Program (a $35 cost that the study will pay to the Fitness 
Center for the subject). Subjects may be required to participate in a maximum of 45 
sessions, although the maximum may not be needed for all subjects. The maximum 
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 7 of 12
compensation is $1800, although the total compensation will be determined by the 
number of sessions that the subject completes while enrolled in the study. 
The data collected will be analyzed offline. All data and medical information of potential 
subjects will be locked in a file cabinet in the office of the PI. All study personnel listed 
will have access to the data and medical information. Subjects will be assigned a code 
when they are enrolled in the study. All GPS data will be analyzed by a researcher who is 
blinded to the subjects' identity. All data will be kept on computer hard-drives with 
accounts and passwords for security. Data will be stored in a locked file cabinet and on a 
secured-access computer. Data will not be destroyed. Only authorized individuals 
working directly in the study will have access to the computers.
Selection and Withdrawal of Subjects
Lower limb transfemoral amputees will be recruited from inpatient and outpatient 
amputee clinics at The Rehabilitation Institute of Chicago and Northwestern Memorial 
Hospital. Criteria will be:
Inclusion criteria
•
Males or females with dysvascular transfemoral amputations
•
6 months or more post prosthetic fitting
•
Homebound or limited community ambulators post amputation
•
Ability to walk >50m in a 2 min walk test
Exclusion criteria
•
Traumatic, cancer or genetic amputation
•
Co-morbidity that completely prevents physical activity 
•
Significant skin lesions/ulcers on stump that prevent fitting of prosthesis
•
Cognitive deficits or visual impairments that would impair their ability to give 
informed consent or to follow simple instructions during experiment 
Withdrawal criteria
•
3 or more consecutive or 5 total per leg missed sessions
•
Hospitalizations
•
At PI’s discretion for unforeseen/unplanned medical events that may alter 
inclusion or exclusion criteria
Subject Recruitment and Screening
Lower limb amputees will be recruited from amputee clinics at RIC and Northwestern. 
Clinicians at these locations will be informed that the Center for Bionic Medicine is 
looking for lower limb amputees who, in their judgment will fill the above criteria. 
Potential research subjects will be referred to Gayatri Mathur, PT, Megan Hermann, PT, 
Kelly Nance PT and Susan Dluhy, PT,. They will be provided with a contact card with 
contact details for the physical therapists. Potential subjects will be informed of the time 
commitment required and questioned regarding the inclusion/exclusion criteria.
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 8 of 12
In addition, research staff on the study will identify potential subjects from RIC’s Cerner 
Information Systems. Once a dysvascular transfemoral amputee has been identified, 
study staff will contact the subject’s clinician and get permission to pre-screen as a 
potential subject. If clinician agrees, clinician may contact potential subject or study staff 
will contact the potential subject on behalf of clinician, initially with a letter followed by 
a phone call to the potential subject. 
A recruitment flyer will be distributed to prosthetists’ offices (e.g. at Hanger, Scheck and 
Siress) for posting/handing out to potential clients who may be interested in learning 
more or participating in the study.
Study staff will also post information about the study by e-mailing members of the 
Midwest Chapter of the American Academy of Orthotists and Prosthestists, which is 
available only to prosthetic and orthotic professionals who are members and live within 
the boundaries of Wisconsin, Illinois and Indiana.  Information about this organization 
may be found at: http://www.oandp.org/membership/chapters/midwest/. The same 
message will also be posted on OANDP-L (OANDP-L@LISTS.UFL.EDU) which is the 
listserver for the exchange of information for orthotics and prosthetics professionals.. 
Finally, Dr. Jayaraman will screen the potential subjects to ensure that they meet the 
inclusion/exclusion criteria. 
Efficacy Assessment
Microprocessor knees have shown to be very effective to improve community mobility 
and quality of life in the K3&K4 amputee population. This protocol seeks to test the 
efficacy of the microprocessor knee (C-leg) in the K2 dysvascular population. 
Safety Assessment
Risk and Injury
The primary risk in this study is the risk of falls, regardless of the prosthesis used. Fall 
prevention is a primary focus and the risk will be reduced by the use of harnesses, gait 
belts, assistive devices as needed and stand-by or contact guard assistance and 
supervision by researchers. All subjects will be initiated with testing and therapy sessions 
with simple activities, progressing on to more dynamic, complex activities when it is 
clear that they are safe and acclimated to the prosthesis being used. Other risks include 
muscle soreness from exercises during therapy sessions. To avoid this, subject will be 
provided with adequate rest periods and subjects will be monitored by questions 
regarding discomfort. Skin irritation from adjusting to a new socket fit can also be a risk. 
This risk will be minimized by regular check ups by a certified prosthetist, who will 
check for skin lesions/breakdowns.
Benefits
The benefits from this study to the individual subjects will only be related to similar 
physical therapy sessions they would receive as part of their rehabilitation. Although the 
immediate benefits of the study to the individual are limited, the entire community of 
transfemoral amputees stands to benefit with a better understanding of functional gains 
and quality of life changes with different prosthetic components. Upon completion of the 

Page 9 of 12
study, the participant may choose to keep the prosthetic foot used in the study if 
continued use is approved by their clinical prosthetist.
Statistical Analysis
The data will be analyzed using Statview version 5.0.1 will be used for statistical 
analysis. Power, the probability of rejecting a false null hypothesis, is fixed at 0.90. Two-
sided significance level is set at 0.05. The sample size required for an attrition rate of 
30% is therefore 40 subjects to be randomized into 2 groups of 20 each. A two way-
repeated measures ANOVA will be used with main factors of prosthetic used and 
repeated testing session. 
5) Anticipated Results & Potential Pitfalls
We anticipate the dysvascular amputees when using the c-leg will significantly improve 
in their functional outcomes, increase their community mobility leading in significant 
health benefits. We do not foresee any potential pitfalls. 
6) Discussion of Next Steps
This research will be critical in establishing the efficacy of using a microprocessor knee 
in the improving functional outcomes and community mobility K2 dysvascular 
population.  While this line of research will have many options of further investigation, 
the particular path this laboratory would like to follow three-fold: 1) does providing 
prosthetic knees with greater functionality help amputees improve their quality of life and 
social re-integration, 2) does prosthetics with greater functionality relate to greater 
exercise leading to reduction in co-morbidities and reduced health costs, 3) does intense 
rehabilitation as part of the amputee rehab contribute to better prosthetic use.
7) Cited References
1) Amputation Statistics by cause Limb Loss in the United States, National Limb Loss 
Information 
Center 
Fact 
sheet, 
from 
www.amputee-
coalition.orf/fact_sheet/amp_stats_cause.html accessed on 1/12/2011.
2) Brodtkorb T-H, Henriksson M, Johannesen-Munk K, Thidell F. Cost-effectiveness of 
C-Leg compared with non–microprocessor-controlled knees: a modeling approach. Arch 
Phys Med Rehabil 2008;89:24-30.
3) Pepper M & Willick S.: Maximizing physical activity in athletes with amputations. 
Curr. Sports Med. Rep., Vol. 8, No. 6, pp. 339Y344, 2009.
4) Stineman MG, KwongPL, Xie D, Kurichi JE, Ripley DC, Brooks DM, Bidelspach DE, 
Bates BE: Prognostic Differences for Functional Recovery After Major Lower Limb 
Amputation: Effects of the Timing and Type of Inpatient Rehabilitation Services in the 
Veterans Health Administration. PM R Apr 2010;2:232-243.
5) Witsø E & Rønningen H: Lower limb amputations: registration of all lower limb 
amputations performed at the University Hospital of Trondheim, Norway, 1994-1997. 
Prosthet Orthot Int 2001 Dec;25(3):181-5.
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 10 of 12
Other References
1) A.H. Vrieling et al: Gait initiation in lower limb amputees. Gait & Posture 27 (2008) 
423–430
2) Andrews KL: Rehabilitation in limb deficiency. 3. The geriatric amputee. Arch Phys 
Med Rehabil 77:S-14-S-17, 1996.
3) Brodtkorb T-H, Henriksson M, Johannesen-Munk K, Thidell F. Cost-effectiveness of 
C-Leg compared with non–microprocessor-controlled knees: a modeling approach. Arch 
Phys Med Rehabil 2008;89:24-30.
4) Brooks D, Parsons J, Hunter JP, Devlin M, Walker J. The 2-minute walk test as a 
measure of functional improvement in persons with lower limb amputation. Arch Phys 
Med Rehabil 2001;82;1478-83.
5) Cumming J, Barr S, Howe TE. Prosthetic rehabilitation for older dysvascular people 
following a unilateral transfemoral amputation. Cochrane Database of Systematic 
Reviews 2006, Issue 4. Art.No.: CD005260. DOI: 10.1002/14651858.CD005260.pub2.
6) Curtze C et al, Balance recovery after an evoked forward fall in unilateral transtibial 
amputees. Gait & Posture 32 (2010) 336–341.
7) Deathe, AB et al: Selection of outcome measures in lower extremity amputation 
rehabilitation: ICF activities. Disability and Rehabilitation, 2009; 31(18): 1455–1473.
8) Ephraim PL, MacKenzie EJ, Wegener ST,Dillingham TR, Pezzin LE. Environmental 
barriers experienced by amputees: the Craig Hospital Inventory of Environmental 
Factors–Short Form. Arch Phys Med Rehabil 2006;87:328-33.
9) Gailey, R et al: Review of secondary physical conditions associated with lower-limb 
amputation and long-term prosthesis use. JRRD Volume 45 Number 1, 2008 Pg 15 – 30.
10) Hafner BJ & Smith DG: Differences in function and safety between Medicare 
Functional Classification Level-2 and -3 transfemoral amputees and influence of 
prosthetic knee joint control. JRRD Volume 46 Number 3, 2009,Pages 417 — 434. 
11) Hafner BJ, Willingham LL, Buell NC, Allyn KJ, Smith DG. Evaluation of function, 
performance, and preference as transfemoral amputees transition from mechanical to 
microprocessor control of the prosthetic knee. Arch Phys Med Rehabil 2007;88:207-17.
12) Highsmith MJ et al: Safety, energy efficiency, and cost efficacy of the C-Leg for 
transfemoral amputees: A review of the literature. Prosthetics and Orthotics International 
December 2010; 34(4): 362–377.
13) Kahle JT et al: Comparison of non-microprocessor knee mechanism versus C-Leg on 
Prosthesis Evaluation Questionnaire, stumbles, falls, walking tests, stair descent, and 
knee preference. JRRD Volume 45 Number 1, 2008, Pages 1 — 14.
14) Kaufman KR et al. Gait and balance of transfemoral amputees using passive 
mechanical and microprocessor-controlled prosthetic knees. Gait & Posture 26 (2007) 
489–493.
15) Kilpatrick MW, R. J. Robertson , J. M. Powers, J. L. Mears, and N. F. Ferrer. 
Comparisons of RPE before, during, and after Self-Regulated Aerobic Exercise. Med. 
Sci. Sports Exerc., Vol. 41, No. 3, pp. 681–686, 2009.
16) Kosak & Smith: Comparison of 2-, 6-, and 12-minute walk tests  in patients with 
stroke, JRRD Volume 42, Number 1, Pages 103–108, January/February 2005
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 11 of 12
17) Lythgo N, Marmaras B, Connor H. Physical function, gait, and dynamic balance of 
transfemoral amputees using two mechanical passive prosthetic knee devices. Arch Phys 
Med Rehabil 2010;91:1565-70.
18) McNealy LL & Gard SS: Effect of prosthetic ankle units on the gait of persons with 
bilateral trans-femoral amputations. Prosthetics and Orthotics International March 2008; 
32(1): 111 – 126.
19) Raya MA et al: Impairment variables predicting activity limitation in individuals with 
lower limb amputation. Prosthetics and Orthotics International March 2010; 34(1): 73–
84.
20) Roberts TL, Pasquina PF, Nelson VS, Flood KM, Bryant PR, Huang ME. Limb 
deficiency and prosthetic management. 4. Comorbidities associated with limb loss. Arch 
Phys Med Rehabil 2006;87(3 Suppl 1):S21-7
21) Roth EJ, Park KL, Sullivan WJ. Cardiovascular disease in patients with dysvascular 
amputation. Arch Phys Med Rehabil 1998;79:205-15.
22) Schoppen T, Boonstra A, Groothoff JW, de Vries J, Go¨eken LN, Eisma WH. 
Physical, mental, and social predictors of functional outcome in unilateral lower-limb 
amputees. Arch Phys Med Rehabil 2003;84:803-11.
23) Segal AD et al: Kinematic and kinetic comparisons of transfemoral amputee gait 
using C-Leg® and Mauch SNS® prosthetic knees. JJRD Volume 43 Number 7, 
November/December 2006 Pages 857 — 870.
24) Stepien JM, Cavenett S, Taylor L, Crotty M: Activity levels among lower-limb 
amputees: self-report versus step activity monitor. Arch Phys Med Rehabil 2007;88: 896-
900.
25) Uustal, Heikki Prosthetic Rehabilitation Issues in the Diabetic and Dysvascular 
Amputee; in The Dysvascular and Diabetic Patient: Update in Diagnosis, Treatment and 
Rehabilitation Physical Medicine and Rehabilitation Clinics of North America Volume 
20, Issue 4, November 2009 pages 689-703.
26) van Velzen JM et al: Physical capacity and walking ability after lower limb 
amputation: a systematic review. Clinical Rehabilitation 2006; 20: 999_1016.
27) Vanicek N, et al. Gait patterns in transtibial amputee fallers vs. non-fallers: 
Biomechanical differences during level walkingGait & Posture 29 (2009) 415–420.28) 
Vanicek N, Strike S, McNaughton L, Polman R. Postural responses to dynamic 
perturbations in amputee fallers versus nonfallers: a comparative study with able-bodied 
subjects. Arch Phys Med Rehabil 2009;90:1018-25.
29) Vrieling AH et al: Gait adjustments in obstacle crossing, gait initiation and gait 
termination after a recent lower limb amputation. Clin Rehabil 2009 23: 659 originally 
published online 26 May 2009.
30) Vrieling AH et al: Obstacle crossing in lower limb amputees. Gait & Posture 26 
(2007) 587–594
31) Vrieling, AH et al: Gait termination in lower limb amputees. Gait & Posture 27 
(2008) 82–90.
32) Williams RM, Turner AP, Orendurff M, Segal AD, Klute GK, Pecoraro J, Czerniecki 
J. Does having a computerized prosthetic knee influence cognitive performance during 
amputee walking? Arch Phys Med Rehabil 2006;87:989-94.
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.

Page 12 of 12
33) Ziegler-Graham K, MacKenzie EJ, Ephraim, PL, Travison TG, Brookmeyer R. 
Estimating the prevalence of limb loss in the United States: 2005 to 2050. Arch Phys 
Med Rehabil 2008;89:422-9.
IRB #: STU00042823 Approved by NU IRB for use on or after 4/17/2018 through 4/16/2019.