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Plantar Pressures and Ground Reaction Forces During Walking of Individuals With Unilateral Transfemoral Amputation


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To describe and compare the plantar pressures, temporal foot roll-over, and ground reaction forces (GRFs) between both limbs of subjects with unilateral transfemoral amputation and with able-bodied participants during walking. We also verify the relevance of a force plate and a pressure plate to discriminate changes in gait parameters of subjects with limb loss. Cross-sectional study. Biomechanics laboratory. 14 subjects with unilateral transfemoral amputation and 21 able-bodied participants. We used a force plate and a pressure plate to assess biomechanical gait parameters while the participants were walking at their self-selected gait speed. We measured plantar pressure peaks in six foot regions and the instant of their occurrence (temporal foot roll-over); and GRF peaks and impulses of anterior-posterior (braking and propulsive phases), medial-lateral, and vertical (load acceptance and thrust phases) components. The thrust, braking, and propulsive peaks, and the braking and propulsive impulses were statistically lower in the amputated limb than in both the sound limb (p<.05) and in able-bodied participants (p<.05). In the amputated limb, we observed higher pressure peaks in the lateral rearfoot and medial and lateral midfoot, and lower values in the forefoot regions compared to the other groups (p<.05). The temporal foot roll-over showed statistically significant differences among the groups (p<.05). The plantar pressures, temporal foot roll-over, and GRFs in subjects with unilateral transfemoral amputation showed an asymmetric gait pattern, and different values were observed in both of their lower limbs as compared to able-bodied subjects during walking. The instruments were able to determine differences between participants in gait pattern, suggesting that both plantar pressure and GRF analyses are useful tools for gait assessment in individuals with unilateral transfemoral amputation. Due to the convenience of pressure plates, their use in the clinical context for prosthetic management appears relevant to guide the rehabilitation of subjects with lower limb amputation.
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Title: Plantar pressures and ground reaction forces during walking of individuals with
unilateral transfemoral amputation
Marcelo Peduzzi de Castro, PhD, MSc, PTa, b, *
Denise Soares, PhD a, b
Emília Mendes, MSc c, d
Leandro Machado, PhD a, b
a Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport,
University of Porto, Porto, Portugal
b Porto Biomechanics Laboratory, University of Porto, Porto, Portugal
c Department of Bioengineering, University of Strathclyde, Scotland UK
d Center of Professional Rehabilitation of Gaia - CRPG, Arcozelo, Portugal
* Corresponding author: Marcelo Peduzzi de Castro
Posta Addres: Laboratory of Biomechanics, College of Sports, University of Porto,
Porto, Portugal. Rua Dr. Plácido Costa, 91 - 4200.450, Porto, PORTUGAL.
Telephone: +351 225074791
Mobile: +351 932234823
Fax: +351 225 500 689
E-mail Address:
Objective: To describe and compare the plantar pressures, temporal foot roll-over, and
ground reaction forces (GRFs) between both limbs of subjects with unilateral
transfemoral amputation and with able-bodied participants during walking. We also
verify the relevance of a force plate and a pressure plate to discriminate changes in gait
parameters of subjects with limb loss.
Design: Cross-sectional study.
Setting: Biomechanics laboratory.
Subjects: 14 subjects with unilateral transfemoral amputation and 21 able-bodied
Methods: We used a force plate and a pressure plate to assess biomechanical gait
parameters while the participants were walking at their self-selected gait speed.
Main outcome measurements: We measured plantar pressure peaks in six foot regions
and the instant of their occurrence (temporal foot roll-over); and GRF peaks and
impulses of anterior-posterior (braking and propulsive phases), medial-lateral, and
vertical (load acceptance and thrust phases) components.
Results: The thrust, braking, and propulsive peaks, and the braking and propulsive
impulses were statistically lower in the amputated limb than in both the sound limb
(p<.05) and in able-bodied participants (p<.05). In the amputated limb, we observed
higher pressure peaks in the lateral rearfoot and medial and lateral midfoot, and lower
values in the forefoot regions compared to the other groups (p<.05). The temporal foot
roll-over showed statistically significant differences among the groups (p<.05).
Conclusions: The plantar pressures, temporal foot roll-over, and GRFs in subjects with
unilateral transfemoral amputation showed an asymmetric gait pattern, and different
values were observed in both of their lower limbs as compared to able-bodied subjects
during walking. The instruments were able to determine differences between
participants in gait pattern, suggesting that both plantar pressure and GRF analyses are
useful tools for gait assessment in individuals with unilateral transfemoral amputation.
Due to the convenience of pressure plates, their use in the clinical context for prosthetic
management appears relevant to guide the rehabilitation of subjects with lower limb
As a consequence of the absence of a natural limb, subjects with unilateral
transfemoral (TF) amputation often complain about pain in the sound limb (SL) [1].
They show a higher prevalence of osteoarthritis [2,3], scoliosis [4], and lumbar pain [5],
as well as lower bone mineral density [4] and reduction of the ability to perform all
desired tasks [6] compared to able-bodied (AB) subjects. Previous studies showed a
longer stance phase and higher ankle, knee and hip joint moments [7] and vertical
ground reaction forces (GRFs) [7-9] in the SL compared to the amputated limb (AL)
and AB subjects. These alterations in load distribution between lower limbs increase the
risk of injuries such as anterior cruciate ligament tears [10] and knee joint osteoarthritis
[3,9] in response to overload. Higher values for the step width [11] and displacement of
the center of pressure in both limbs of the individuals with lower limb amputation
compared to AB subjects have also been reported [12,13].
The prosthesis is limited in its mechanical functionality when the dynamic
movement changes, resulting in movement-specific compensatory mechanisms in the
residual joints and intact limb [14]. The alterations in gait features promoted by the
adaptation to a prosthetic limb may cause or reinforce physical impairments. During the
alignment process of the prosthesis and gait training in subjects with lower extremity
amputation, a prosthetic foot roll-over as close as possible to the physiological foot [15]
and bilateral symmetry [16] are pursued. This process is highly subjective and variable
[17], leading to the need for instruments able to easily and reliably provide quantitative
measurements of the gait of individuals with limb loss in order to help and improve the
rehabilitation process [17].
The analysis of plantar pressures is considered clinically useful in identifying
anatomical deformities on the foot, in guiding the diagnosis and treatment of gait
disorders, and in preventing pressure ulcers [18,19]. The plantar pressure peak is the
main parameter used in plantar pressure analysis and reflects the highest pressure to
occur in a specific region of the foot during the stance phase. The instant of the pressure
peaks also can be calculated, allowing recognition of the sequence of recruitment of
different regions of the foot (loosely referred in the present study as temporal foot roll-
over). However, the validity of the plantar pressure analysis is not yet well established,
and its clinical applicability in the case of prosthetic feet is minimal. Geil and Lay [17]
investigated the capacity of a plantar pressure analysis system to identify alterations in
transtibial amputees’ prosthetic alignment for clinical purposes. These authors observed
that angular changes in the prosthetic alignment in the frontal plane produce predictable
shifts in the plantar pressures between lateral and medial foot regions, concluding that
plantar foot pressure analysis is a sensitive and feasible tool to help clinicians quantify
gait parameters and the way these parameters are influenced by the prosthetic alignment
Regarding the SL, although some studies have evidenced its overload during gait
[1,7-9], to the best of our knowledge, the identification of the plantar pressure
distribution pattern, temporal foot roll-over features, and specific overloaded regions
were not yet addressed. This information may help clinicians prevent plantar foot
injuries such as blisters, callosity, or skin ulcerations by avoiding the development of
regions with high pressure peaks, and may also guide gait training programs. The light-
weight plantar pressure plates could be a feasible and practical way to record these data.
Information about mechanical stress can be obtained from vertical force analysis
[20]. The vertical GRF provides the global aspect of the vertical forces, while the
plantar pressure analysis informs about the distribution of this force along the plantar
surface of the foot [21]. The vertical GRF is related to joint contact forces and can
therefore provide insights about the development of some pathological conditions, such
as back pain and osteoarthritis [20]. Increased vertical forces represent a decreased
capacity of the musculoskeletal system in absorbing the body loading during gait [22]
and, as a consequence, express an increment on the likelihood of developing overuse
injuries [23]. The anterior-posterior GRF informs about the friction between the sole
and floor, relevant for assessing foot-related injuries (e.g. blister or ulceration) and
tendency to slip [24]. The medial-lateral GRF has been suggested to provide
information about gait balance [23]. The GRF are influenced by gait speed, where the
increase of speed promotes linear increases in the GRF peaks [25] and decreases the
GRF impulses [26]. In the present study, the GRF peaks and GRF impulses were
calculated. While the peak variables are widely used and inform about the highest forces
experienced by the body, the impulse variables provide complementary information
related to the amount of force received by the body during a given activity. Based on the
viscoelastic properties of the musculoskeletal tissues, the peak variables appear to be
more insightful in showing aggressive loads to the body. However, in terms of gait
pattern and long-term adaptations, the impulse variables might also provide valuable
information about the kinetic features of walking.
The GRFs provide global information about the vertical and shear stress forces,
whereas the plantar pressure analysis identifies the distribution of the vertical GRF over
the plantar foot surface [21]. The combination of both analyses provides more detailed
and complementary information about specific features of forces acting on the
prosthetic and the sound limbs. Such information might be useful in verifying the
effects of adjustments in prosthesis components and different therapeutic approaches to
gait performance. Hence, the aim of this study is to describe and compare plantar
pressures, temporal foot roll-over, and GRF parameters between both limbs of subjects
with unilateral TF amputation and with AB subjects during walking. The plantar
pressure and GRF data were also analyzed in order to verify their relevance in
determining differences between participants in gait parameters of individuals with
unilateral TF amputation walking.
This is a cross-sectional study with a convenience sample. This project was
approved by the ethical board from the Professional Rehabilitation Center of Gaia and
all participants freely signed an informed consent based on the Declaration of Helsinki.
Two groups of participants were analyzed. For the experimental group, patients
with unilateral TF amputation were selected from the rehabilitation center’s database.
Patients who had been living with unilateral TF amputation for at least two years were
included, whereas those who had a prosthesis with electronically controlled knee or
prosthetic ankle with energy storing system, and/or who presented pain or lacked
independent walking (without the help of some kind of aid device) ability were
excluded. The AB participants were selected from the project of physical activity for
elderly developed at the university engaged in this study. They were excluded if they
presented any musculoskeletal impairment, limitation, or pain during walking.
Fourteen subjects with TF amputation, 13 male and one female, with mean age
of 56.7 ± 11.7 years old and mean body mass of 71.4 ± 11.7 kg were enrolled in this
study. All participants had undergone the amputation more than nine years prior to the
experiment. Twelve amputations were traumatic, one from osteomyelitis complications,
and one from vascular disease; in these non-traumatic cases, the individuals did not
show any sign of co-morbidity or difficulty in gait related to the pathology that caused
the amputation. Twelve of the participants used a modular prosthesis of endoskeletal
type and two the exoskeletal type. Twelve prostheses had a prosthetic foot with
articulated ankle and two with fixed ankle; all of them presented a friction-controlled
knee joint, where 12 were uniaxial and two polyaxial. All prosthetic sockets were of
total contact type without the use of a pelvic suspension belt. All individuals had
concluded the adaptation and prosthesis alignment process, a process completed by the
same two technicians in all cases. Participants used their own shoes (standard classic
shoes), which were provided by the same manufacturer, and they were all of similar
type (not orthopedic shoes). Furthermore, the prosthesis was individually aligned for
these shoes. They had no special insole inside. The AB group was composed of six men
and 15 women with a mean age of 68.3 ± 9.4 years old and mean body mass of 66.0 ±
9.0 kg. They also wore their own shoes, which were their preferred ones and were of the
same type as the entire AB group (athletic shoes).
As a measure of the capacity and physical independence of the participants, the
questionnaire SF-36 v.2 was applied and the physical function domain was analyzed
We used a pressure plate (RsScan, Olen, Belgium) measuring 0.5 m x 0.4 m,
with a spatial resolution of 2.7 sensors/cm² operating at 300 Hz to capture pressure data.
To collect the GRFs, we used a piezoelectric force plate (Kistler Instruments AG,
Winterthur, Switzerland) operating at 1000 Hz. Both plates were calibrated before the
study, and they were synchronized by an external trigger that started them
Data acquisition
We used the FootScan 7 gait 2nd generation software (RsScan, Olen, Belgium)
to acquire the pressure plate data (Figure 1), while SIMI Motion System® software
(SIMI Reality Motion Systems, Unterschleissheim, Germany) was used for data
acquisition of the force plate.
--Insert Figure 1--
The pressure plate was positioned over the force plate and they were placed in
the middle of an 8 m walkway. Anti-slip mats were placed along the trajectory to avoid
unlevel ground cause by the pressure plate. The participants were familiarized with the
environment by freely walking over the walkway. During data collection, the
participants walked at their self-selected speed. They performed at least seven steps
(three before and three after stepping on the plate). The participants with amputation
performed six valid trials, three of them recording data from the AL and three from the
SL. The AB participants performed three valid trials with their right leg. The trial was
considered valid if the participants hit the plate with the entire foot over it and did not
alter their gait pattern. Alterations in the gait pattern such as step length or pace were
assessed subjectively by visual inspection comparing the gait performed during the
familiarization time and the trials.
Data analysis and outcome measures
Data from the pressure plate (values of each sensor at each frame) and force
plate (three components of the GRFs) were exported to Matlab® 7.0 (MathWorks,
Massachusetts, USA), and a program for data processing and variable calculations was
developed. The shoe imprint (hereafter loosely referred to as foot) was divided into six
regions: in the longitudinal (anterior/posterior) direction, the boundary between rearfoot
and midfoot was located at 73% of foot length, measured from toes to heel, and that
between midfoot and forefoot was located at 45% along this length [28]. Each region
was further divided in two parts, 50% medial and 50% lateral.
We calculated two plantar pressure and 10 global GRF dependent variables. The
plantar pressure variables were calculated for all six foot regions and were (i) the
pressure peak (unit, N/cm2), which was defined as the peak of the average of all active
sensors in the region, and (ii) temporal foot roll-overthe instant of pressure peak
(unit, % of the stance phase), which was defined as the moment of occurrence of the
pressure peak. The GRF variables were as follows (Figure 2):
- Stance phase duration time from the first contact to toe off;
- Load acceptance peak (VLA-Peak) first peak (highest value at the first half of
the curve) from the vertical GRF;
- Thrust peak (VT-Peak) second peak (highest value at the second half of the
curve) from the vertical GRF;
- Braking peak (APB-Peak) lowest value (negative peak) from the anterior-
posterior GRF;
- Propulsive peak (APP-Peak) highest value (positive peak) from the anterior-
posterior GRF;
- Medial-lateral peak (MLPeak) the highest value from the medial-lateral GRF;
- Load acceptance impulse (VLA-Imp) time integral from the first foot contact
until midstance (minimum between VLA-Peak and VT-Peak) from the vertical GRF;
- Thrust impulse (VT-Imp) time integral from midstance to toe-off from the
vertical GRF;
- Braking impulse (APB-Imp) time integral from the first contact to middle zero
from the anterior-posterior GRF;
- Propulsive impulse (APP-Imp) time integral from the middle zero to toe-off
from the anterior-posterior GRF.
--Insert Figure 2--
The variables were calculated for the three groups under study. The GRFs were
normalized by body weight (the weight of the prosthesis was added to the body weight).
In the present study, an asymmetric pattern was considered present when statistically
significant differences were found between AL and SL in any variable [29].
Statistical analysis
The mean of the three repetitions of each group (AL, SL and AB groups) was
computed and statistical procedures were performed with these values. Data normality
was verified by the Shapiro-Wilk test and homogeneity of variances by the Levene’s
test. The between-trial repeatability of all variables was verified by the intraclass
correlation coefficient (ICC). In order to compare the variables among the groups,
paired student’s t-tests (AL vs. SL) and independent student’s t-tests (SL vs. AB and
AL vs. AB) were used. As there was only one female in the experimental group, and in
the control group there were more females than males, we also used independent
student’s t-tests to compare males and females in the control group. The statistical
procedures were performed using SPSS software (SPSS Inc, Chicago, IL, USA) with an
α value set at 0.05.
All data showed normality of distribution and homogeneity of variance. The ICC
values were above 0.90 for all variables, indicating excellent inter-trial repeatability.
The AL showed shorter stance time compared to SL (AL= 0.88 ± 0.12 s vs. SL= 1.02 ±
0.12 s; p=.003) and higher stance time than AB (0.73 ± 0.10 s; p=.001), and the AB
participants also showed shorter stance time than the SL (p<.001). The values of the
questionnaire SF-36 were 62.8 ± 24.9 points for the subjects with lower limb
amputation and 82.3 ± 18 points for the AB participants. There was no statistically
significant difference between males and females in the control group for any parameter
(p<.05these results are in appendix 1).
The pressure peaks showed statistically significant differences among the three
groups (AL, SL, and AB). The AL showed higher pressure peaks on the lateral rearfoot
and lateral midfoot compared to the AB group, and higher pressure peaks on the medial
midfoot than the AB and SL groups. No differences were found on the medial rearfoot
among groups. The AL presented lower pressure peaks than AB on the medial forefoot
and also lower values than AB and SL on the lateral forefoot (Figure 3a).
The temporal foot roll-over also showed statistically significant differences
among the three groups (Figure 3b). In both rearfoot regions the instants of pressure
peaks occurred earlier in both AL and SL compared to the AB. In the medial midfoot,
the instants of pressure peaks occurred statistically significantly later in the AL
compared to the SL and AB, and in the lateral midfoot they occurred earlier in the SL
compared to the AL and AB. In the AL group, the instants of pressure peaks occurred
earlier in the lateral and medial forefoot compared to the AB.
--Insert Figure 3--
The three GRF components were statistically different among the groups. The
AL showed lower VT-Peak and VLA-imp, and lower braking (APB-Peak and APB-Imp) and
propulsive (APP-Peak and APP-Imp) forces than the SL and AB groups. For the MLPeak, the
AL showed higher values than the SL and AB groups. The SL presented higher VT-Imp
and APB-Imp and lower VT-Peak, APB-Peak, and VLA-imp than the AB participants (Table 1
and Figure 4).
--Insert Table 1 --
--Insert Figure 4--
This study was conducted to describe and compare plantar pressure and GRF
parameters between both limbs of individuals with TF amputation (AL and SL) and
with AB subjects during gait. As an indicator of physical function, the SF36
questionnaire showed that the subjects with lower limb amputation have lower values
than their able-bodied counterparts. Nevertheless, these data indicate that they felt few
limitations to performing daily living activities involving physical function and,
therefore, the gait of both groups of participants appears suitable to be compared. We
observed an asymmetrical pattern in pressure peaks, temporal foot roll-over, and GRF
variables when the participants with TF amputation walked. Furthermore, statistically
significant differences in both SL and AL compared to the AB participants were also
identified. Both plantar pressure and GRF analyses were able to discriminate differences
in gait pattern among the groups. To the best of our knowledge, no studies presenting
values of plantar pressures on subjects with TF amputation are available in the literature
to compare with our results. Nevertheless, other studies analyzing the center of pressure
[12,13], GRFs [7,8,30], lower limb kinematics [30], and joint moments [7] also found
an asymmetrical pattern when subjects with TF amputation walked. However, it is not
clear whether these asymmetries are necessary (in both magnitude and pattern) to
promote safety during walking and compensate for the difficulties inherent to walking
with a prosthetic limb [31] or whether they should be reduced in order to promote a
kinetic gait pattern as symmetric as possible to decrease the injury risks caused by
overloading or unloading [9].
During shod walking at a medium speed, healthy older adults showed plantar
pressure peaks ranging from 10 N/cm2 (medial midfoot) to 23 N/cm2 (medial forefoot)
and 25 N/cm2 (central forefoot) [32]. In the current study, the plantar pressure peaks in
the AB group ranged from 8 N/cm2 (medial midfoot) to 18 N/cm2 (lateral rearfoot), in
the AL from 10 N/cm2 (lateral forefoot) to 25 N/cm2 (lateral rearfoot), and in the SL
from 13 N/cm2 (medial and lateral midfoot) to 18 N/cm2 (lateral rearfoot). Therefore,
even with different plantar pressure systemsin-shoe [32] vs. pressure plate (present
study)similar magnitudes of plantar pressures were observed. This increases the
external reliability of our findings.
A set of studied parameters provided information regarding the beginning of the
stance phase: pressure platemedial and lateral rearfoot pressure peaks and their
instants of occurrence, and force plateVLA-Peak, VLA-Imp, APB-Peak, and APB-Imp. The
present findings suggest that both instruments were able to identify differences between
the subjects with amputation and AB participants while they walked. Subjects with TF
amputation did not show a higher load acceptance peak (VLA-Peak) in the SL compared to
the prosthetic one, but they did present higher vertical GRF impulse (VLA-Imp). Thus, as
the impulse variables are influenced by the magnitude and duration of force application,
the longer time spent on the sound limb (compared to the prosthetic limb) is likely to be
the main reason for this behavior, which might play an important role in the higher
levels of knee pain and knee osteoarthritis observed in the SL [1-3].
Changes in the temporal foot roll-over in both lower limbs of subjects with
unilateral TF amputation compared to subjects without any amputation and an altered
plantar pressure distribution between the medial and lateral rearfoot region in the AL
were identified by plantar pressure analysis. Such events could not be identified by the
GRF analysis as it assesses the overall GRFs and ground reaction moments and,
therefore, does not provide any information about how the forces are being distributed
among different plantar foot regions.
The asymmetrical plantar pressure distribution and the changes in the temporal
foot roll-over in the AL might be a consequence of the absence of physiological knee
and ankle joints, which causes altered motor control of the prosthetic limb [33].
Michaud et al. [34] found an increased pelvic obliquity during the prosthetic swing in
individuals with unilateral lower limb amputation, suggesting hip hiking. As a result,
earlier instants of pressure peaks at the beginning of the stance phase might occur due to
the prosthetic foot’s abrupt landing. Hip hiking was also evidenced by the lower APB-
Peak and APB-Imp observed in the AL compared to the SL and AB. It is possible that the
increased motion in the frontal plane (hip hiking) resulted in a more vertical landing
with the prosthetic foot, reflected in lower anterior-posterior forces (braking forces).
This also indicates difficulties in decelerating the prosthetic limb at the beginning of the
stance phase. The possible slower gait speed of the participants with TF amputation
may have also contributed to these lower braking peaks in the prosthetic limb. Sapin et
al. [30], corroborating our results, observed a lower capacity for braking in subjects
with TF amputation who used a single-axis prosthetic knee (that coordinates ankle and
knee flexion), and in those using other knee joints without a kneeankle link.
Considering the SL, we observed an earlier occurrence of the pressure peaks in the
rearfoot and midfoot of the SL compared to the AB. This may reflect a strategy to
compensate for the lower stability in the late stance with the prosthetic limb. Thus the
stance with the SL was anticipated and the maximal weight bearing in the rearfoot and
midfoot also occurred earlier.
At the midstance phase, in which the medial and lateral midfoot pressure peaks
occur, higher values of pressure peaks and later instants of their occurrence were found
for both regions in the AL. These higher magnitudes of pressure might be caused by the
need for the subjects with TF amputation to block their prosthetic knee in extension
[35]. Moreover, at the midstance phase, the prosthetic knee tends to be in extension as
the line of action of the GRFs passes over or anterior to the center of the knee joint
[31]. Pressure peaks for the AL were postponed in the midfoot regions, possibly to
spend more time in this phase, as subjects consider it the most stable phase of stance.
Considering the MLPeak, both AL and SL showed higher values compared to AB
participants. As subjects with TF amputation showed a higher vertical displacement of
the center of mass in order to block the knee in extension [8,35], one may expect a
larger body movement on the frontal plane [34] to smooth out this greater center of
mass vertical displacement, resulting in higher values of MLPeak, as found in the present
study. The significantly increased load the in SL [8,35], the hip-hiking pattern, and the
lower control of the AL for lowering the pelvis on the SL side before the initial foot
contact might also contribute to these higher magnitudes of MLPeak [36], which might
reflect gait instability.
We found at the late stance the most different behaviors among groups in
pressure peaks (medial and lateral forefoot peaks), temporal foot roll-over, and GRFs
(VT-Peak, VT-Imp, APP-Peak and APP-Imp). The AL displayed lower values in almost all of
these variables, and earlier instants of pressure peaks compared to the SL and AB
groups. Similar results were found in patients using a prosthetic limb, with or without a
knee-ankle link [30]. The plantar flexor muscles are responsible for plantar flexion
during the gait propulsion phase, and their absence implies the recruitment of the hip
flexors to lift the foot, anticipating the AL swing phase [33]. Therefore, the lower values
that we observed might be caused by the absence of these muscles [37]. Moreover, all
participants used a Solid-Ankle Cushioned Heel (SACH) foot. This foot includes a solid
ankle and a rigid keel that runs along the length of the prosthetic foot until the end of
the midfoot, with most of the forefoot mainly composed of flexible, rubber-type
material that does not provide any support or energy return.
The higher GRF impulses, pressure peaks in the medial forefoot, and the longer
stance phase duration in the subjects with TF amputation suggest a significantly bigger
load in the SL during walking. Nolan et al. [8] analyzed four subjects with TF
amputation and found higher vertical GRF impulses in the SL compared to the AL and
AB groups, whereas a longer stance and a shorter swing phase in the SL were observed
in previous studies [8,13,35]. The subjects with TF amputation raise their body by
excessive plantar flexion of the sound foot in a well-known compensatory mechanism
ie, vaulting. This behavior could occurr as an adaptive mechanism to increase the foot
clearance of the prosthetic foot and to protect the residual limb (AL) by charging it with
load for less time [8]. Because mechanical forces are related to joint damage and
dysfunctions such as those found in osteoarthritis [3], this “protective pattern” in
subjects with unilateral TF amputation might be one of the causes for the high incidence
of dysfunction in the SL [3].
Pressure plates allow the collection of information related to the interface
between shoe sole and ground, while in-shoe pressure systems capture data related to
the plantar foot surface interface and the internal surface of the shoe. We chose a
pressure plate in this study for its convenience and ease of use for clinical purposes.
Moreover, the effect promoted by the deformable interface of the shoe could exert
major influence on pressure insole measurements [38]. The insole sensors could be
affected by the internal environment of the shoe, such as temperature, contour, and
humidity [39]. Furthermore, the presence of cables attached to the individuals,
necessary for in-shoe pressure systems, could prove to be another conditioning factor
affecting the gait pattern.
The present study showed that both plantar pressures and GRF are sensitive to
detecting alterations in gait patterns when subjects with TF amputation walked.
However, using both instruments in a clinical context might be complex and expensive.
As using a pressure plate does not require an elaborate laboratorial set up, it is cheaper
and more practical than using a force plate (i.e., pressure plates are smaller and lighter
than force plates), its use for analyzing different aspects of gait training and prosthesis
alignment is suggested. Moreover, data regarding AB subjects can be used to guide the
interpretation of data from patients with lower limb amputation, providing some
indications about the plantar foot regions that should be more or less used by AB
subjects while walking. However, this interpretation should be made with caution, and
data from AB subjects are not suggested to be a template that should be matched.
Angular changes between the pylon and the socket in the frontal plane during
prosthetic alignment shift the plantar pressure in a lateral/medial direction [17]. This
information could be used during prosthesis alignment to identify an imbalance of
pressures between medial and lateral plantar foot regions. After that step, alterations in
prosthesis alignment could be tested and the clinician could use data from AB subjects,
gait symmetry, or any other criteria in agreement with the aim of intervention to
improve the gait pattern. Future studies on the influence of specific muscle
strengthening, special insoles or shoes, gait training, and prosthesis components on
pressure distribution would provide a vast amount of quantitative information for
rehabilitation purposes. Such findings could be used to verify the most appropriate
approach to diminish gait asymmetry to an optimum level.
The adopted walking speed in this study was the one at which the subjects felt
most comfortable (self-selected). Thus, an identical gait speed for the subjects with TF
amputation and AB participants was not warranted. Based on the differences in duration
of the stance phase between the experimental and control groups, it is plausible to
assume the participants with TF amputation walked slower than their able-bodied
counterparts. A previous study [40] assessing AB subjects observed similar plantar
pressure peaks between slow and normal self-selected gait speeds. In Taylor et al.’s [40]
study, the duration of the stance phase for slow gait speed was 0.82 ± 11.1 s and for
normal gait speed was 0.70 ±5.2 s. The differences in the duration of stance phase
between groups in our study were only slightly higher (AB = 0.73 ± 0.10, AL= 0.88 ±
0.12 and SL 1.02 ± 0.12) than in the aforementioned study [40]. Therefore, we believe
that the possible differences in gait speed between groups had only small effects on the
plantar pressure parameters. On the other hand, the GRF peaks increase linearly with
increasing gait speed [25], and the GRF impulses decrease with increasing gait speed
[26]. Thus, the comparisons between the GRF parameters from the AL and SL with
those from the AB should be made with caution. Our subjective analysis of gait speed
during data collection was that the participants with TF amputation walked slightly
slower than the AB participants. We adopted the self-selected gait speed in order to
prevent disturbances in gait patternscaused by restricting speed with treadmills or
using a metronomeand ensure normal walking.
Other limitations should also be considered in the present study. The distribution
between men and women among the participants was not homogenous. However, we
did not observe any difference between able-bodied males and females for any
parameter. Putti et al. [41] also reported that there are no differences in plantar pressure
parameters between genders. Only the right lower limbs of the AB participants were
assessed; however, similar GRFs and plantar pressures have been shown between limbs
[42,43]. The shoe types were different between groups (TF amputees and AB
participants). Using new shoes or ones different from those usually worn could alter the
prosthesis alignment and gait pattern. In order to preserve a situation as real as possible
while causing the least interference in gait patterns, the participants were asked to use
their own shoes, which were of similar type inside the groups. Finally, the clinical
usefulness of the analyses used in the present studyGRFs and, mainly, plantar
pressuresas tools to guide and follow the rehabilitation process must be interpret with
caution, as there was no follow-up to verify the effects of intervention (i.e. gait training
or changes in prosthesis alignment) using these instruments.
The participants with unilateral TF amputation showed an asymmetrical plantar
pressure distribution and GRF patterns. In terms of plantar pressure distribution,
temporal foot roll-over, and GRFs, both lower limbs from the participants with TF
amputation (AL and SL) were different from the AB subjects. The GRFs suggest a
significantly increased load in the SL, whereas the plantar pressure analysis suggests a
higher recruitment of the lateral rearfoot and medial and lateral midfoot regions, and a
lower recruitment of the medial and lateral forefoot on the AL compared to the SL and
AB groups. Both systems seemed to be able to discriminate between the lower limbs of
individuals with unilateral TF amputation. The pressure plate seems to be a useful and
sensitive instrument for gait evaluation of subjects with limb loss.
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Table 1. Between group comparison of ground reaction force variables
AL vs. AB
SL vs. AB
AL vs. SL
AL vs. AB*
SL vs. AB*
AL vs. SL*
AL vs. AB*
SL vs. AB*
AL vs. SL*
AL vs. AB*
SL vs. AB
AL vs. SL*
AL vs. AB*
< .001
SL vs. AB*
AL vs. SL
AL vs. AB*
SL vs. AB*
AL vs. SL*
AL vs. AB*
SL vs. AB*
AL vs. SL*
AL vs. AB*
SL vs. AB*
AL vs. SL*
AL vs. AB*
SL vs. AB*
AL vs. SL
AL = amputated limb; SL = sound limb; AB = able-bodied; SD = standard
deviation; CI lower = lower bound of 95% confidence interval; CI upper =
upper bound of 95% confidence interval. * = significant difference between
groups with p<.0.5.
Figure 1. Distribution of the plantar pressures, as acquired by FootScan 7 gait 2nd
generation, of one participant from one group.
Figure 2. Ground reaction force dependent variables.
Figure 2 legend:
VLA-Peak Load acceptance peak; VT-Peak Thrust peak; APB-Peak Braking peak; APP-
Peak Propulsive peak; MLPeak Medial-lateral peak; VLA-Imp Load acceptance
impulse; VT-Imp Thrust impulse; APB-Imp Braking impulse; APP-Imp Propulsive
Figure 3. (A) Plantar pressure peaks and (B) Temporal foot roll-overinstant of the
plantar pressure peaks for the three groups.
Figure 3 legend:
Equal symbols in the groups represent statistically significant difference between *
Amputated limb and Sound limb, Amputated limb and Able-bodied and between #
Sound limb and Able-bodied with p<.05.
Figure 4. Ground reaction forces (GRF) of all tests and all participants. (A) Anterior-
posterior GRF, (B) Medial-lateral GRF, and (C) Vertical GRF.
Figure 4 legend:
Equal symbols in the groups represent statistically significant difference between *
Amputated limb and Sound limb, Amputated limb and Able-bodied and between #
Sound limb and Able-bodied with p<.05. As all the MLPeak were in the same direction
(positive values) and, only some participants showed negative values at the edge of the
curve (first or last 20% of the stance phase), we have opted to present graphically only
absolute positive values of the medial-lateral GRF.
... Due to the loss of physiological joint and muscle functions and accompanying gait alterations, patients with unilateral lower limb amputations (ULLA) usually present asymmetric interlimb gait patterns and deviations from normal gait in spatiotemporal and ground reaction force (GRF) parameters [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The stance time of the prosthetic limb, for example, is shorter when compared to the intact limb, while the swing and step times are longer [1,[3][4][5]7,8,11,12,14,[17][18][19][20][21]. The stance time of the intact limb is even J. ...
... Med. 2022, 11, 2683 2 of 15 longer than the stance time presented by able-bodied people [11,14,21]. Additionally, the step length presents interlimb asymmetries, patient-dependent [9,14,22] either being longer [1,12,13,20,23] or shorter [7,18] for the prosthetic limb. ...
... The step width of patients with ULLA, on the contrary, is constantly higher when compared to able-bodied people [5,18,24], whereas their walking speed is generally reduced [2,3,7,15,22,25]. The weight-acceptance and the push-off peak of the vertical component of the ground reaction force (GRF) are higher on the intact limb [4,6,8,14,16,18,19,21], though, in patients with transfemoral amputations, the weight-acceptance peak might also be higher on the prosthetic limb [15,18]. Compared to the peaks of the able-bodied, they show the tendency to be smaller [4,6,19,21]. ...
Full-text available
Unilateral lower limb amputations usually present with asymmetric interlimb gait patterns, in the long term leading to secondary physical conditions and carrying the risk of low physical activity and impairment of general health. To assess prosthetic fittings and rehabilitation measures, reference values for asymmetries as well as the most significant gait parameters are required. Kinetic gait data of 865 patients with unilateral lower limb amputations (hip and knee disarticulations, transfemoral, transtibial and foot amputations) and 216 able-bodied participants were quantitatively assessed by instrumented gait analyses. Characteristic spatiotemporal (stance time, walking speed, step length and width) and ground reaction force parameters (weight-acceptance and push-off peak) were contrasted to normal gait. All spatiotemporal and ground reaction force parameters differed significantly from normal gait with the largest differences in transfemoral amputations. These also differed between amputation levels and showed age-dependencies. The stance time and push-off peak difference were identified as the most discriminative parameters with the highest diagnostic specificity and sensitivity. The present results mark the first step to establishing universal reference values for gait parameters by means of which the quality and suitability of a prosthetic fitting and the rehabilitation progress can be assessed, and are generalizable for all adults with unilateral lower limb amputations in terms of level walking.
... For trans-femoral amputees, GRF obtained on the prosthetic side showed reductions in 2 nd peak of the vertical GRF, peak braking force, compared to both the contra-lateral side of the amputees and the able-bodied [114]. This is likely caused by hip hiking in coronal plane, which may induce a more vertical landing of the prosthetic limb in early stance phase. ...
... With comparison to the values reported in the literature, up to 12%, 50% and 35% reduction in peak GRF was found in anterior-posterior GRF, medial-lateral GRF and vertical GRF [114,234]. ...
The lower limb prosthetic socket provides a critical interface, which transfers loads between the ground and the residuum. Many amputees report issues related to residuum pain primarily induced by poor socket fit, leading to unsatisfactory rehabilitation outcomes. From a scientific perspective, residuum and socket have been treated as a rigid body. Effective methods, which could provide quantitative measurements of multi-directional loads (i.e. the kinetics) and relative motion (i.e. kinematics) at the residuum/socket interface, are not currently available. The in-situ measurement of kinematic and kinetic parameters and indeed their correlations during amputee walking would help to obtain a comprehensive understanding of the biomechanics at the critical residuum/socket interface. In this thesis, means of assessing residuum/socket interface mechanics has been developed, incorporating the kinematics and kinetics, to comprehend the interface biomechanics. A novel kinematic model was developed to evaluate the interface kinematics based on a 3D motion capture system. The model was applied on both knee disarticulation and trans-tibial participants. Repeatable interface kinematic waveforms (coefficient of multiple correlation of up to 0.988) were obtained on level walking studies over a 2-year period. The model is highly sensitive to walking speed, terrain and prosthetic components. For example, a 21% of increase in walking speed led to an increase in angular and axial displacements of approximately 23% and 6%, respectively. In addition, a novel tri-axial pressure and shear (TRIPS) sensor system, capable of measuring both dynamic pressure and shear stresses, was used to evaluate the interface kinetics as a function of gait cycle (GC). The multi-directional stresses obtained from key loading bearing locations of the residuum suggested that the interface loading is dependent on walking speed, terrain, prosthetic components and socket suspension system. For example, changes to the latter by the removal of one sock resulted in a reduction of the stresses at the proximal location of approximately 30% and an increase of stresses at the distal location of the residuum of up to 28%. Subsequently, the combination of the novel kinematic model and the body interface sensor system was applied to study their correlation, providing a first-of-its-kind approach which shed light on the in-situ interface biomechanics. The method for assessing socket interface mechanics established here therefore provides a stepping stone to quantitatively assist in the socket fitting process and the monitoring of residuum tissue health.<br/
... Lower relative GRF values in all gait phases (vF 1 , vF 3 , a-pF 1 , and a-pF 2 ) except in the middle stance (vF 2 ) were observed for the amputated limb. de Castro et al. [28] observed similar values of a relative vGRF (101.6 for vF 1 and 97.9 for vF 3 ) in a group of patients aged 56.7 ± 11.7 years. However, relative anterior-posterior ground reaction force (a-pGRF) component values assessed by de Castro et al. [28] at initial stance and terminal stance were lower in comparison to our patients (7.12 for a-pF 1 and 7.4 for a-pF 2 ). ...
... de Castro et al. [28] observed similar values of a relative vGRF (101.6 for vF 1 and 97.9 for vF 3 ) in a group of patients aged 56.7 ± 11.7 years. However, relative anterior-posterior ground reaction force (a-pGRF) component values assessed by de Castro et al. [28] at initial stance and terminal stance were lower in comparison to our patients (7.12 for a-pF 1 and 7.4 for a-pF 2 ). Schaarschmidt et al. [29] showed similarities to our results of vGRF in the middle stance (in the underweight phase) and terminal stance (in the overweight phase). ...
Full-text available
The aim of this paper is to present the current state of research on gait parameters in people after unilateral amputation above the knee joint and to compare these gait parameters with those of healthy people. The relevant literature does not include any similar publications. Modern prostheses do not eliminate the asymmetry of gait, although its consequences are diminished. An above-knee amputation leads to significant differences in ground reaction force parameters (GRF) between the sound and amputated limb. The amputated limb is charac­te­rised by lower values of vertical and antero-posterior GRF parameters in comparison with the intact limb. Moreover, during the contact of the heel with the ground, the degree of hip joint flexion of the amputated limb decreases in comparison with the intact limb. Other symptoms of asymmetry between the limbs include asymmetry of pelvic movement in the transverse plane and of the range of movement in the ankle joint. De­creased muscle torque on the hip joint in the amputated limb additionally increases asymmetry of biome­chanical gait parameters after unilateral transfemoral amputation.
... However, prosthetic knees are normally locked during the stance phase for stability, and ESF is not allowed. The loss of function is compensated by the intact side, which has 20% longer supporting time and absorbs twice the impact (Gard, 2006;Hof et al., 2007;Castro et al., 2014). Consequently, forces and impulses are repetitively applied to the intact limb, leading to greater incidences of osteoarthritis (Kulkarni et al., 1998). ...
Full-text available
Prosthetic knees are state-of-the-art medical devices that use mechanical mechanisms and components to simulate the normal biological knee function for individuals with transfemoral amputation. A large variety of complicated mechanical mechanisms and components have been employed; however, they lack clear relevance to the walking biomechanics of users in the design process. This article aims to bridge this knowledge gap by providing a review of prosthetic knees from a biomechanical perspective and includes stance stability, early-stance flexion and swing resistance, which directly relate the mechanical mechanisms to the perceived walking performance, i.e., fall avoidance, shock absorption, and gait symmetry. The prescription criteria and selection of prosthetic knees depend on the interaction between the user and prosthesis, which includes five functional levels from K0 to K4. Misunderstood functions and the improper adjustment of knee prostheses may lead to reduced stability, restricted stance flexion, and unnatural gait for users. Our review identifies current commercial and recent studied prosthetic knees to provide a new paradigm for prosthetic knee analysis and facilitates the standardization and optimization of prosthetic knee design. This may also enable the design of functional mechanisms and components tailored to regaining lost functions of a specific person, hence providing individualized product design.
... Asymmetric gait can be evaluated by analyzing gait cycle, step mechanics, range of motion, and the composing values of GRFs [8]. Individuals with lower limb amputation have an obvious difference in symmetry of gait when compared to able-bodied individuals [9,10], and gait asymmetry comes with significant increases in load on the intact limb [11]. The prosthetic limb is unable to duplicate the control and mechanism of the intact limb [12] making asymmetric gait unavoidable. ...
Full-text available
Background: Individuals with unilateral transfemoral amputation are prone to developing health conditions such as knee osteoarthritis, caused by additional loading on the intact limb. Such individuals who can run again may be at higher risk due to higher ground reaction forces (GRFs) as well as asymmetric gait patterns. The two aims of this study were to investigate manipulating step frequency as a method to reduce GRFs and its effect on asymmetric gait patterns in individuals with unilateral transfemoral amputation while running. Methods: This is a cross-sectional study. Nine experienced track and field athletes with unilateral transfemoral amputation were recruited for this study. After calculation of each participant's preferred step frequency, each individual ran on an instrumented treadmill for 20 s at nine different metronome frequencies ranging from - 20% to + 20% of the preferred frequency in increments of 5% with the help of a metronome. From the data collected, spatiotemporal parameters, three components of peak GRFs, and the components of GRF impulses were computed. The asymmetry ratio of all parameters was also calculated. Statistical analyses of all data were conducted with appropriate tools based on normality analysis to investigate the main effects of step frequency. For parameters with significant main effects, linear regression analyses were further conducted for each limb. Results: Significant main effects of step frequency were found in multiple parameters (P < 0.01). Both peak GRF and GRF impulse parameters that demonstrated significant main effects tended towards decreasing magnitude with increasing step frequency. Peak vertical GRF in particular demonstrated the most symmetric values between the limbs from - 5% to 0% metronome frequency. All parameters that demonstrated significant effects in asymmetry ratio became more asymmetric with increasing step frequency. Conclusions: For runners with a unilateral transfemoral amputation, increasing step frequency is a viable method to decrease the magnitude of GRFs. However, with the increase of step frequency, further asymmetry in gait is observed. The relationships between step frequency, GRFs, and the asymmetry ratio in gait may provide insight into the training of runners with unilateral transfemoral amputation for the prevention of injury.
... Asymmetries on amputees have been often investigated in terms of spatio-temporal variables [6,7], joint kinematics [8,9], joint kinetics [10,11], and GRF [6,7,12]. In these works, the assessment of the symmetry level is mostly calculated using the symmetry index, originally proposed by [13]. ...
Full-text available
The calculation of symmetry in amputee gait is a valuable tool to assess the functional aspects of lower limb prostheses and how it impacts the overall gait mechanics. This paper analyzes the vertical trajectory of the body center of mass (CoM) of a group formed by transfemoral amputees and non-amputees to quantitatively compare the symmetry level of this parameter for both cases. A decomposition of the vertical CoM into discrete Fourier series (DFS) components is performed for each subject’s CoM trajectory to identify the main components of each pattern. A DFS-based index is then calculated to quantify the CoM symmetry level. The obtained results show that the CoM displays different patterns along a gait cycle for each amputee, which differ from the sine-wave shape obtained in the non-amputee case. The CoM magnitude spectrum also reveals more coefficients for the amputee waveforms. The different CoM trajectories found in the studied subjects can be thought as the manifestation of developed compensatory mechanisms, which lead to gait asymmetries. The presence of odd components in the magnitude spectrum is related to the asymmetric behavior of the CoM trajectory, given the fact that this signal is an even function for a non-amputee gait. The DFS-based index reflects this fact due to the high value obtained for the non-amputee reference, in comparison to the low values for each amputee.
... Weakness of the hip abductors leads to asymmetrical gait and reduced ability to avoid unnecessary movements in the frontal plane (e.g. Trendelenburg gait) for maintenance of the body center of mass over the support limb during the stance phase and, ultimately, can lead to reduced PWS [6,7,9,26]. Therefore, isokinetic hip extension power and hip abduction power asymmetry, as identified here, can be used in combination as excellent muscle performance criteria in gait rehabilitation programs focused on increasing walking speed to a functional level in individuals with LLA [13]. ...
Background Preferred walking speed (PWS) is an indicator of walking ability, prosthetic walking potential, and function following a lower-limb amputation (LLA). There is a link between lower-limb muscle performance and PWS in individuals with LLA. However, the ability of select hip muscle performance parameters to determine PWS in these individuals still needs to be thoroughly investigated. Research question Which hip muscle and joint torque parameters best determine PWS in persons with LLA? Methods Seventeen patients with LLA (6 transfemoral, 4 knee disarticulation, and 7 transtibial; 16 men, 1 woman; mean age ± standard deviation, 56 ± 15yr) participated in this cross-sectional study. Maximal joint torque and power were evaluated unilaterally, for both amputated and intact limbs, in isometric and isokinetic conditions during hip flexion/extension (60°/s and 180°/s) and abduction/adduction (30°/s and 90°/s). PWS was measured at habitual walking speed over a 10-m distance. Pearson's correlation coefficient was used to verify the degree of association between each torque parameter and PWS and multiple regression analysis was performed to identify the best predictors of PWS. The level of significance was p < 0.05. Results Correlations between hip muscle performance parameters and PWS were found in most cases (r = 0.51–0.82; p ≤ 0.036–0.0005). The multiple regression model revealed that the best independent predictors of PWS were hip extension power at 180°/s on the amputated side (r² = 0.672; p < 0.0005) and the asymmetry of hip abduction power at 30°/s (r² = -0.147; p < 0.008), accounting together for 82% of the variance in PWS. Significance Lesser hip extension power on the amputated side and greater hip abduction power asymmetry between limbs are detrimental to PWS in persons with LLA. These muscle groups and performance parameters should be considered during gait rehabilitation to assist individuals with LLA in achieving functional waking speed.
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Conventional leg prostheses do not convey sensory information about motion or interaction with the ground to above-knee amputees, thereby reducing confidence and walking speed in the users that is associated with high mental and physical fatigue1–4. The lack of physiological feedback from the remaining extremity to the brain also contributes to the generation of phantom limb pain from the missing leg5,6. To determine whether neural sensory feedback restoration addresses these issues, we conducted a study with two transfemoral amputees, implanted with four intraneural stimulation electrodes⁷ in the remaining tibial nerve ( identifier NCT03350061). Participants were evaluated while using a neuroprosthetic device consisting of a prosthetic leg equipped with foot and knee sensors. These sensors drive neural stimulation, which elicits sensations of knee motion and the sole of the foot touching the ground. We found that walking speed and self-reported confidence increased while mental and physical fatigue decreased for both participants during neural sensory feedback compared to the no stimulation trials. Furthermore, participants exhibited reduced phantom limb pain with neural sensory feedback. The results from these proof-of-concept cases provide the rationale for larger population studies investigating the clinical utility of neuroprostheses that restore sensory feedback.
Background: Inappropriate biomechanical loading usually leads to a high incidence of hip and knee osteoarthritis (OA) in individuals with lower-limb amputation, and prosthetic alignment may be an important influencing factor. The effect of alignment on the lower limb loading remains quantitatively unclear, and the relationship between malalignment and joint diseases is undefined. Research question: How does alignment affect spatiotemporal gait parameters and ground reaction force (GRF) in individuals with transfemoral amputation? Methods: Gait tests of 10 individuals with transfemoral amputation were performed with recommended alignment and eight malalignments, including 10 mm socket translation (anterior, posterior, medial, and lateral) and 6° socket angular changes (flexion, extension, abduction, and adduction). Fifteen individuals without amputation were recruited as a control group. The differences in spatiotemporal and GRF parameters under different alignments were analyzed and compared with those of the control group. Statistical analyses were performed by one-way ANOVA, repeated measure multivariate ANOVA, and paired t tests. Results: The medial GRF peaks and impulse on both sides and load rate on the intact side are significantly higher than those of the control group (P < 0.0056). The propulsive and braking peaks, vertical impulse, and medial and vertical load rates of GRF on the intact side are higher than those on the residual side (P < 0.05). The alignment of socket adduction significantly increases medial GRF peak and impulse on both sides (P < 0.0056). Significance: Alignments exert remarkable and complicated effects on the biomechanical performance. The considerably higher GRF on the intact side of the individuals with transfemoral amputation may lead to internal stress changes of the intact joint, which may be an inducement for high incidence of joint diseases. Probably due to the increased lateral deviation of the center of gravity, the socket adduction alignment significantly increases medial GRF, which may lead to an increased risk of knee OA.
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A unilateral transtibial amputation causes a disruption to the musculoskeletal system, which results in asymmetrical biomechanics. The current study aimed to assess the movement asymmetry and compensations that occur as a consequence of an amputation when performing a countermovement vertical jump. Six unilateral transtibial amputees and 10 able-bodied (AB) participants completed 10 maximal vertical jumps, and the highest jump was analyzed further. Three-dimensional lower limb kinematics and normalized (body mass) kinetic variables were quantified for the intact and prosthetic sides. Symmetry was assessed through the symmetry index (SI) for each individual and statistically using the Mann-Whitney U test between the intact and prosthetic sides for the amputee group. A descriptive analysis between the amputee and AB participants was conducted to explore the mechanisms of amputee jumping. The amputee jump height ranged from 0.09 to 0.24 m. In the countermovement, all ankle variables were asymmetrical (SI > 10%) and statistically different (p < .05) for the amputees. At the knee and hip, there was no statistical difference between the intact and prosthetic sides range of motion, although there was evidence of individual asymmetry. The knees remained more extended compared with the AB participants to prevent collapse. In propulsion, the prosthesis did not contribute to the work done and the ankle variables were asymmetrical (p < .05). The knee and hip variables were not statistically different between the intact and prosthetic sides, although there was evidence of functional asymmetry and the contribution tended to be greater on the intact compared with the prosthetic side. The lack of kinetic involvement of the prosthetic ankle and both knees due to the limitation of the prosthesis and the altered musculoskeletal mechanics of the joints were the reason for the reduced height jumped.
Individuals with transfemoral amputation must adapt their gait to the absence of one natural limb, causing an impact throughout the body. A better understanding of these changes would provide safer and more efficient development of prevention and rehabilitation strategies. The aim of this study was to compare the center of pressure (CoP) variables between the amputated limb and the sound limb of subjects with transfemoral amputation and able-bodied subjects during gait. A FootScan pressure plate (RsScan, Olen, Belgium) was used to record the CoP motion of 14 individuals with transfemoral amputation (56.7 ± 11.7 years old) and 21 physically active able-bodied subjects (68.3 ± 9.4 years old) during gait at self-selected speed. The data showed a normal distribution pattern, and statistical tests showed significant differences (p < 0.05) at various spatial and temporal variables of CoP between the amputees' lower limbs, as well as differences between both limbs of people with amputation and able-bodied subjects. There seems to be a compensation in the sound limb caused by the lack of a contralateral physiological limb that culminates in taking the subject out of the normal range. The CoP has an asymmetrical pattern in the lower limbs during gait of individuals with transfemoral amputation; consequently, prevention and interventions strategies in this population may consider these characteristics.
In-shoe plantar pressure measurement has the potential to play a crucial role in the screening, treatment and behavior modification of patients who are at risk of, or are experiencing a variety of foot problems. In this article we review the instrumentation, methodology, applications, and rationale for in-shoe plantar pressure measurement. Possible new applications in the future are also discussed. In-shoe techniques are advantageous compared to the more traditional platform devices because they permit the most important interface, that between the foot and shoe, to be monitored and they allow for increased versatility of measurement for the calculation of more robust statistical estimates. Both discrete transducers and matrix systems have been developed; each approach has its advantages and disadvantages but, in general, matrix systems are preferable. Although there are still device limitations which must be overcome the technique of in-shoe measurement has opened the door to a whole new realm of pressure studies both in research and clinical practice.
The common denominator in the assessment of human balance and posture is the inverted pendulum model. If we focus on appropriate versions of the model we can use it to identify the gravitational and acceleration perturbations and pinpoint the motor mechanisms that can defend against any perturbation.We saw that in quiet standing an ankle strategy applies only in the AP direction and that a separate hip load/unload strategy by the hip abd/adductors is the totally dominant defence in the ML direction when standing with feet side by side. In other standing positions (tandem, or intermediate) the two mechanisms still work separately, but their roles reverse. In the tandem position ML balance is an ankle mechanism (invertors/evertors) while in the AP direction a hip load/unloading mechanism dominates.During initiation and termination of gait these two separate mechanisms control the trajectory of the COP to ensure the desired acceleration and deceleration of the COM. During initiation the initial acceleration of the COM forward towards the stance limb is achieved by a posterior and lateral movement of the COP towards the swing limb. After this release phase there is a sudden loading of the stance limb which shifts the COP to the stance limb. The COM is now accelerated forward and laterally towards the future position of the swinging foot. Also ML shifts of the COP were controlled by the hip abductors/adductors and all AP shifts were under the control of the ankle plantar/dorsiflexors. During termination the trajectory of both COM and COP reverse. As the final weight-bearing on the stance foot takes place the COM is passing forward along the medial border of that foot. Hyperactivity of that foot's plantarflexors takes the COP forward and when the final foot begins to bear weight the COP moves rapidly across and suddenly stops at a position ahead of the future position of the COM. Then the plantarflexors of both feet release and allow the COP to move posteriorly and approach the COM and meet it as quiet stance is achieved. The inverted pendulum model permitted us to understand the separate roles of the two mechanisms during these critical unbalancing and rebalancing periods.During walking the inverted pendulum model explained the dynamics of the balance of HAT in both the AP and ML directions. Here the model includes the couple due to the acceleration of the weight-bearing hip as well as gravitational perturbations. The exclusive control of AP balance and posture are the hip extensors and flexors, while in the ML direction the dominant control is with the hip abductors with very minor adductor involvement. At the ankle the inverted pendulum model sees the COM passing forward along the medial border to the weight-bearing foot. The model predicts that during single support the body is falling forward and being accelerated medially towards the future position of the swing foot. The model predicts an insignificant role of the ankle invertors/evertors in the ML control. Rather, the future position of the swing foot is the critical variable or more specifically the lateral displacement from the COM at the start of single support. The position is actually under the control of the hip abd/adductors during the previous early swing phase.The critical importance of the hip abductors/adductors in balance during all phases of standing and walking is now evident. This separate mechanism is important from a neural control perspective and clinically it focuses major attention on therapy and potential problems with some surgical procedures. On the other hand the minuscule role of the ankle invertors/evertors is important to note. Except for the tandem standing position these muscles have negligible involvement in balance control.
This study compared the ground reaction forces (GRF) and plantar pressures between unloaded and occasional loaded gait. The GRF and plantar pressures of 60 participants were recorded during unloaded gait and occasional loaded gait (wearing a backpack that raised their body mass index to 30); this load criterion was adopted because is considered potentially harmful in permanent loaded gait (obese people). The results indicate an overall increase (absolute values) of GRF and plantar pressures during occasional loaded gait (p < 0.05); also, higher normalized (by total weight) values in the medial midfoot and toes, and lower values in the lateral rearfoot region were observed. During loaded gait the magnitude of the vertical GRF (impact and thrust maximum) decreased and the shear forces increased more than did the proportion of the load (normalized values). These data suggest a different pattern of GRF and plantar pressure distribution during occasional loaded compared to unloaded gait.
The objective of the study was to investigate gait symmetry in transfemoral amputees using a hydraulic- and a microprocessor-controlled knee prosthesis. An A-B design with repeated measurements was chosen, and the measurements were carried out at a prosthetics/orthotics rehabilitation center. Nine unilateral transfemoral C-Leg bearing amputees participated in the study, of whom five subjects completed the study. Three-dimensional inverse dynamic gait analysis was performed on each subject. Each subject was then fitted with a 3R60 prosthesis. After a 1-week acclimation period, gait analysis was performed on the 3R60 prosthesis. The outcome measures were temporospatial symmetry, duration of single support on the sound side and the prosthetic side, and the introduced butterfly symmetry ratio. Spatial symmetry was not significantly different between the two prosthetic knees. Temporal symmetry was not significantly improved when subjects used the C-Leg. Single support was significantly longer on the sound side than on the prosthetic side (p < 0.05). However, no significant difference was observed between the two prosthetic knees. The butterfly symmetry ratio was not significantly improved when subjects used C-Leg. The butterfly patterns differed remarkably across subjects, which indicates different gait strategies, but the gait patterns within subjects were not influenced by the type of prosthetic knee. In conclusion, none of the outcome measures investigated showed a significantly improved gait symmetry when subjects used C-Leg compared with the mechanical prosthetic knee 3R60.
Primary disabling conditions, such as amputation, not only limit mobility, but also predispose individuals to secondary musculoskeletal impairments, such as osteoarthritis (OA) of the intact limb joints, that can result in additive disability. Altered gait biomechanics that cause increased loading of the intact limb have been suggested as a cause of the increased prevalence of intact limb knee and hip osteoarthritis in this population. Optimizing socket fit and prosthetic alignment, as well as developing and prescribing prosthetic feet with improved push-off characteristics, can lead to reduced asymmetric loading of the intact limb and therefore are potential strategies to prevent and treat osteoarthritis in the amputee population. Research on disabled populations associated with altered biomechanics offers an opportunity to focus on the mechanical risk factors associated with this condition. Continued research into the causes of secondary disability and the development of preventive strategies are critical to enable optimal rehabilitation practices to maximize function and quality of life in patients with disabilities.