bioenergetic measures in a limited selection of prosthetic feet
including solid ankle cushioned heel (SACH), energy-storing,
and vertical shock
–absorbing feet.
7
Brie
fly, compared to alter-
natives such as SACH feet, TTA
’s studied preferred energy-
storing feet and reported enhanced performance, comfort and
less effort in association with their use.
7
–12
In some cases,
additional functions have resulted in improved performance of
speci
fic functional needs. Examples include specialty running
feet improving bioenergetic ef
ficiency during ambulation
above comfortable walking speeds and vertical shock absorp-
tion improving stair-climbing kinetics.
13,14
Despite the avail-
able, however limited evidence, there is no empirical data
to demonstrate which higher functioning prosthetic feet can
maximize an injured service member
’s ability to continue
performing at a level commensurate with return to duty.
Obstacle courses (OCs) are a familiar element of military
and law enforcement culture and quali
fication. They are used
in preparatory training and skill maintenance in physically
demanding work environments. OCs are further used for
assessment to demonstrate continued preparedness in terms
of skill pro
ficiency and fitness. Use of OCs have become
even more widespread to include recreation and to determine
disease severity. In the health care literature for instance,
OCs have been used with the elderly, those using assistive
mobility aids, visually impaired, community ambulatory
transfemoral amputees, those recovering from cardiac events,
firefighters, and the military.
15
–24
Use of OCs in these exam-
ples have provided determinations of
fitness and situational
preparedness for physically rigorous work environments.
Given that OCs are familiar to military personnel to assess
physical preparedness and because there are no
field-based
physical performance assessments of high-functioning TTAs
using high-functioning prosthetic feet, use of an OC is a log-
ical assessment choice in this population. Therefore, the
purpose of this study was to determine which of three high-
functioning, energy-storing prosthetic feet maximize perfor-
mance and preference in a rigorous
field OC. A second
purpose was to quantify the differences in physical perfor-
mance between persons with TTA and a high-functioning
nonamputee control group.
METHODS
The protocol was approved by Institutional Review Boards
for the University of South Florida and the U.S. Army. The
study was also listed in a federal clinical trials registry
(www.clinicaltrials.gov; no. NCT01404559).
Study Design
A randomized, double-blind (subjects and data collectors),
repeated measures experimental design was used to compare
three prosthetic feet conditions in physical performance. The
study statistician (also blinded to the interventions) used an
electronically generated, randomized, and balanced block
allocation to sequence independent variable (prosthetic foot)
assignment to subjects (off-site and concealed) via the study
prosthetists. The study prosthetists fabricated prosthetic
blinding covers that concealed the identity of prosthetic feet
during testing to mask participants and investigators.
Subject Recruitment and Eligibility
TTA subjects were recruited in collaboration with case man-
agers through a military treatment facility specializing in
amputee rehabilitation as well as advertisement with local
prosthetic and rehabilitative clinics. Nonamputee control sub-
jects were recruited through the local County Sherriff Depart-
ment
’s Special Weapons and Tactics Team (SWAT). All
subjects had to be aged
≤45 years and provide evidence of
medical clearance to be able to participate in vigorous physi-
cal activity. Nonamputee control subjects had to be a SWAT
team member. Additional eligibility criteria speci
fic to TTAs
included that candidates had to be determined by study pros-
thetists to be at the K4 functional level and currently active
duty military or other uniformed service, a recently separated
Veteran or have a strong high-performance athletic history as
an amputee (e.g., ranked triathlete, paralympian).
Experimental Procedures
Study Feet (Independent Variables)
All amputee subjects (experimental group) were tested in
random order with each of the following three energy-storing
prosthetic feet (blinded) (Fig. 1).
(1) Vari
flex (Ossur, Reykjavik, Iceland. Energy-storing
and return [ESR]),
(2) Elite Blade (Endolite, Hampshire, United Kingdom.
Energy-storing and vertical shock absorption),
(3) Re-Flex Rotate (Ossur, Reykjavik, Iceland. Energy-
storing and vertical shock and torsion absorption).
These feet were selected as they represent differing types
of energy-storing feet including a basic energy-storing foot,
a light weight ESR foot with vertical shock absorption and
a heavier ESR foot with vertical shock and torsion absorp-
tion. A cross-section of nonamputees were also assessed to
provide a comparison to unimpaired physical performance
(control group).
Prosthetic Fitting and Accommodation Periods
Board-certi
fied and state-licensed study prosthetists dupli-
cated TTA participants
’ prosthetic sockets and suspension.
The duplicate socket was then
fit and aligned (to manufac-
turer speci
fications using a LASAR posture tool [Otto Bock
Healthcare, Duderstadt, Germany]) with the three 3 pros-
thetic feet using modular coupling components to control
potential confounding issues related to socket
fit. TTA partic-
ipants accommodated with each prosthetic foot by wearing it
for a minimum of 7 days (minimum of 8 hours per day). Par-
ticipants recorded their foot accommodation use in a written
journal provided to them during
fitting and training. Usage
MILITARY MEDICINE, Vol. 181, November/December Supplement 2016
46
Energy-Storing and Shock-Adapting Prosthetic Feet in Transtibial Amputees