MILITARY MEDICINE, 181, 11/12:45, 2016
Differences in Military Obstacle Course Performance Between
Three Energy-Storing and Shock-Adapting Prosthetic Feet in
High-Functioning Transtibial Amputees: A Double-Blind,
Randomized Control Trial
CPT M. Jason Highsmith, SP USAR*†‡§; Jason T. Kahle, MSMS, CPO, FAAOP‡;
Rebecca M. Miro, PhD‡∥; Derek J. Lura, PhD¶; Stephanie L. Carey, PhD**;
Matthew M. Wernke, PhD††; Seok Hun Kim, PT, PhD‡;
CDR William S. Quillen, MSC USN (Ret.)‡∥
ABSTRACT Background: Approximately 683 persons engaged in military service experienced transtibial amputation
(TTA) related to recent war in Iraq and Afghanistan. Military TTAs function at a level beyond basic ambulation. No
empirical data demonstrate which higher functioning prosthetic feet maximize injured service personnel
’s ability to con-
tinue performing at a level commensurate with return to duty. This study
’s purpose was to determine which of three
high-functioning, energy-storing prosthetic feet maximize performance and preference in a
field obstacle course (OC)
and to quantify physical performance differences between TTAs and high-functioning nonamputees. Procedures: A ran-
domized, double-blind, repeated measures experimental design compared three prosthetic feet (Ossur Vari
flex, Endolite
Elite Blade, and Ossur Re-Flex Rotate) during performance on a
field OC. TTAs accommodated with study feet and the
OC before assessment. 14 TTAs and 14 nonamputee controls completed the course. Subjective and objective perfor-
mance differences were compared across feet conditions and between groups. Results: Total OC completion times were
similar between prosthetic feet: Elite-Blade (419 seconds ± 130), Vari
flex (425 seconds ± 144), and Re-Flex Rotate
(444 seconds ± 220). Controls
’ OC completion time (287.2 seconds ± 58) was less ( p ≤ 0.05) than TTA times. In total,
controls had faster completion times ( p
≤ 0.05) compared to all prosthetic feet conditions in 13/17 obstacles. Re-Flex
Rotate had 2 additional obstacles different ( p
≤ 0.05) than controls and required more time to complete. Median RPE
values were lower ( p
≤ 0.05) for controls than TTA regardless of foot. Regarding foot preference for OC completion,
7/14 (50%) preferred Elite Blade, 5/14 (36%) preferred Re-Flex Rotate, and the remaining 2/14 (14%) preferred
Vari
flex. Conclusion: Controls completed the OC faster and with less effort than TTAs regardless of prosthetic foot. No
clear differences in prosthetic feet emerged during OC completion; however, individual task performance, perceived
effort, and preference resulted in trends of slight performance improvement with and preference for Elite Blade, a dual
function energy-storing and return foot combined with vertical shock absorption. Understanding how to maximally
improve performance in such functional tasks may allow service members to best sustain physical
fitness, return to their
military occupational specialty and possibly in-theater duty.
INTRODUCTION
Traumatic amputation represents more than 2% of all battle-
field injuries and greater than 7% of major extremity injury
associated with military service.
1,2
Speci
fic to the wars in
Iraq and Afghanistan, there have been 1,221 persons engaged
in military service who have experienced 1,631 amputations
from 2001 to 2011.
3
Of these, 683 amputations (or 41.8%)
were at the transtibial level and 366 people suffered multiple
amputations.
1
–4
Military transtibial amputation (TTAs) likely
function at a level beyond basic ambulation and will require
a longer duration of care over their remaining lifespan com-
pared to dysvascular amputees in the civilian sector. Today
’s
younger military TTA will challenge the health care sys-
tem that is best suited for management of lower function-
ing patients.
5,6
Rehabilitation following TTA routinely involves use of a
prosthesis. Optimizing the TTA prosthesis requires selecting
componentry, including a prosthetic foot best suited for the
patient
’s particular functional demands. Problematically, lit-
tle empirical data are available to guide selection of the opti-
mal foot for a high-functioning member of the armed forces
who may be interested in extreme recreational pursuits as a
Veteran or in staying on active military duty. Available
comparative effectiveness research for prosthetic feet in the
TTA population has included perceptive, biomechanical, and
*Extremity Trauma & Amputation Center of Excellence, 2748 Worth
Road, Suite 29, Fort Sam Houston, TX 78234.
†James A. Haley Veterans Administration Hospital, Center of Innova-
tion in Disabilities and Rehabilitation Research, 8900 Grand Oak Circle
(151R), Tampa, FL 33637.
‡School of Physical Therapy and Rehabilitation Sciences, University of
South Florida, 3515 E, Fletcher Avenue, Tampa, FL 33612.
§U.S. Department of Veterans Affairs, Rehabilitation and Prosthetics
Services, 810 Vermont Avenue, NW Washington, DC 20420.
∥Center for Neuromusculoskeletal Research, University of South Flor-
ida, 3515 E, Fletcher Avenue, Tampa, FL 33612.
¶Department of Bioengineering and Software Engineering, Florida Gulf
Coast University, 10501 FGCU Boulevard South, Fort Myers, FL 33965.
**Mechanical Engineering Department, University of South Florida,
4202 E, Fowler Avenue, ENB 118,Tampa, FL 33612.
††Willow Wood, 15441 Scioto Darby Road, P. O. Box 130, Mount
Sterling, OH 43143.
doi: 10.7205/MILMED-D-16-00286
MILITARY MEDICINE, Vol. 181, November/December Supplement 2016
45