Part III. Physical medicine and rehabilitation service. Mil Med 2006;
171(3): 206
–8.
20. Spinger BA, Doukas WC: Process of care for battle casualties at Walter
Reed Army Medical Center: Part II. Physical therapy service. Mil Med
2006; 171(3): 203
–5.
21. Goldberg KF, Green B, Moore J, et al: Integrated musculoskeletal reha-
bilitation care at a comprehensive combat and complex casualty care
program. J Manipulative Physiol Ther 2009; 32: 781
–91.
22. Granville R, Menetrez J: Rehabilitation of the lower-extremity war-
injured at the center for the intrepid. Foot Ankle Clin 2010; 15(1):
187
–99.
23. Bosse MJ, MacKenzie EJ, Kellam JF, et al: An analysis of outcomes of
reconstruction or amputation of leg-threatening injuries. N Engl J Med
2002; 347: 1924
–31.
24. Thuan VL, Travison TG, Castillo RC, et al: Ability of lower-extremity
injury severity scores to predict functional outcome after limb salvage.
J Bone Joint Surg Am 2008; 90(8): 1738
–43.
25. Melcer T, Sechriest VF, Walker J, Galarneau M: A comparison of
health outcomes for combat amputee and limb salvage patients
injured in Iraq and Afghanistan wars. J Trauma Acute Care Surg 2013;
75(2 Suppl 2): S247
–S254.
26. Stinner DJ, Burns TC, Kirk KL, et al: Prevalence of late amputations
during the current con
flicts in Afghanistan and Iraq. Mil Med 2010;
175: 1027
–9.
27. Krueger CA, Wenke JC, Ficke JR: Ten years at war: comprehen-
sive analysis of amputation trends. J Trauma Acute Care Surg 2012;
73(6 Suppl 5): S438
–S44.
28. Huh J, Stinner DJ, Burns TC, Hsu JR; Late Amputation Study Team:
Infectious complications and soft tissue injury contribute to late amputa-
tion after severe lower extremity trauma. J Trauma 2011; 71(1 Suppl):
S47
–S51.
29. Ellington JK, Bosse MJ, Castillo RC, MacKenzie EJ; LEAP Study
Group: The mangled foot and ankle: results from a 2-year prospective
study. J Orthop Trauma 2013; 27(1): 43
–8.
MILITARY MEDICINE, Vol. 181, November/December Supplement 2016
29
Improving Outcomes Following Extremity Trauma
MILITARY MEDICINE, 181, 11/12:30, 2016
The Prevalence of Gait Deviations in Individuals
With Transtibial Amputation
Christopher A. Rábago, PT, PhD*†; Jason M. Wilken, PT, PhD*†
ABSTRACT Individuals with a transtibial amputation (TTA) are at increased risk for developing secondary musculo-
skeletal disorders as a result of multiple gait deviations. These deviations are primarily characterized using group mean
comparisons, which do not establish if deviations are prevalent, of large magnitude, or both. In contrast, use of norma-
tive reference ranges and prevalence speci
fically identifies the percentage of individuals outside of a predefined accept-
able range. The purpose of this study was to identify and characterize gait deviations in service members with
unilateral TTA using group mean comparisons and normative reference ranges (able-bodied mean ± 2 SD). Temporal
spatial, kinematic, and kinetic data were collected during biomechanical gait assessments of 40 able-bodied males and
16 males with a TTA. Highly prevalent and statistically signi
ficant deviations were observed at the ankle and knee of the
prosthetic limb and hip of the intact limb in the TTA group. Approximately 20% of measures that were signi
ficantly
different between groups demonstrated 0% deviation prevalence. Deviations in the prosthetic limb were in agreement
with literature, although most intact limb deviations were not. Further study is needed to determine the exact etiology
of these deviations, and their association with the development of secondary musculoskeletal conditions.
INTRODUCTION
Individuals with lower extremity amputations are at increased
risk for developing secondary musculoskeletal disorders as a
result of persistent gait deviations associated with prosthetic
use.
1
Compared to age-matched peers without amputation,
World War II veterans with transtibial amputation (TTA)
showed an increased incidence of knee and hip osteoarthritis
later in life (mean age = 71.8 years); 30 to 35 years after their
amputation.
2,3
Individuals with a unilateral TTA were also
88% more likely to develop osteoporosis in the amputated
limb compared to the general population.
4
In addition, 60% of
individuals with a TTA reported the onset of back pain within
2 years of amputation and 63% categorized pain as moderate
to severe.
5
Gait deviations and compensations such as asym-
metric single limb stance time
1,6
and increased vertical ground
reaction forces at the intact limb
3,7
–9
are thought to exacerbate
these musculoskeletal degenerative processes. Early identi
fica-
tion of gait deviations and formal training of gait mechanics,
especially in young individuals with a TTA, could help pre-
vent a lifetime of poor gait mechanics and reduce the risk of
developing secondary musculoskeletal conditions.
Few studies have systematically determined the effect of
a TTA on temporal spatial, kinematic, and kinetic measures
on a per person basis. Gait deviations are often characterized
using group mean comparisons of individuals with a TTA
to able-bodied (AB) participants.
10
–17
However, individuals
with a TTA in these studies often vary considerably in age
(20
–77 years) and prosthetic experience (1–59 years),
11,12,15,16
which may reduce statistical power because of increased inter-
subject variability.
18
A reduction in statistical power lessens
the probability that signi
ficant differences (i.e., deviations) will
be detected. Further, many of these studies have fewer than
10 participants,
10,13
–17,19
which limits rigorous statistical anal-
ysis.
19
To achieve statistical signi
ficance using group mean
comparisons, a high proportion of values from the TTA group
must be consistently greater or less than the AB group mean;
or a few individuals with a TTA must have suf
ficiently large
deviations to bias their group mean. As a result, the reader
is often unable to determine if a given deviation is prevalent,
of large magnitude, or both.
An alternate approach for identifying gait deviations in
individuals with a TTA is to compare their data against nor-
mative reference ranges (NRR), which are calculated using
mean and variability data from an AB group.
20
A value from
an individual with a TTA that falls outside the NRR is con-
sidered a deviation in that speci
fic measure. Prevalence of
deviations in each measure can then be determined as the per-
centage of a population that functions outside the established
NRR.
20
–23
Deviations identi
fied using a NRR approach are
indicative of abnormal mechanics in each individual, which
may be missed when comparing the mean performance of a
patient population to mean performance of an AB group.
Further, prevalence provides an easy-to-understand metric,
which indicates the frequency of deviations, not described
using traditional group mean comparisons.
The prevalence of gait deviations, as identi
fied using a
NRR approach, has yet to be determined for a group of indi-
viduals with TTA. The combination of both group mean
comparisons and prevalence data could be used to identify
gait deviations most likely encountered when treating indi-
viduals with a TTA. Therefore, the purpose of this study
*Center for the Intrepid, Department of Rehabilitation Medicine, Brooke
Army Medical Center, 3551 Roger Brooke Drive, Joint Base San Antonio,
Fort Sam Houston, TX 78234.
†Extremity Trauma and Amputation Center of Excellence, 2748 Worth
Road, Suite 29, Joint Base San Antonio, Fort Sam Houston, TX 78234.
The view(s) expressed herein are those of the authors and do not re
flect
the of
ficial policy or position of Brooke Army Medical Center, the U.S. Army
Medical Department, the U.S. Army Of
fice of the Surgeon General, the
Department of the Army and Department of Defense, or the U.S. Government.
doi: 10.7205/MILMED-D-15-00505
MILITARY MEDICINE, Vol. 181, November/December Supplement 2016
30