- Email: [email protected]
Temporal-Spatial Values During a 180° Step Turn in People with Unilateral Lower Limb Amputation
Accepted Manuscript Title: Temporal-Spatial Values during a 180◦ Step Turn in People with Unilateral Lower Limb Amputation Authors: Sheila M. Clemens, Glenn K. Klute, Neva J. Kirk-Sanchez, Michele A. Raya, Kyoung Jae Kim, Ignacio A. Gaunaurd, Robert S. Gailey PII: DOI: Reference:
S0966-6362(18)30553-8 https://doi.org/10.1016/j.gaitpost.2018.05.016 GAIPOS 6098
To appear in:
Gait & Posture
Received date: Revised date: Accepted date:
21-2-2018 2-5-2018 10-5-2018
Please cite this article as: Clemens SM, Klute GK, Kirk-Sanchez NJ, Raya MA, Kim KJ, Gaunaurd IA, Gailey RS, Temporal-Spatial Values during a 180◦ Step Turn in People with Unilateral Lower Limb Amputation, Gait and Posture (2010), https://doi.org/10.1016/j.gaitpost.2018.05.016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Manuscript Title: Temporal-Spatial Values during a 180 ˚ Step Turn in People with Unilateral Lower Limb Amputation Authors: Sheila M. Clemensa,b, Glenn K. Klutec,d, Neva J. Kirk-Sancheza, Michele A. Rayaa, Kyoung Jae Kima, Ignacio A. Gaunaurda,b, Robert S. Gaileya,b
aDepartment
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Institutions: of Physical Therapy, Miller School of Medicine, University of Miami, Coral Gables,
FL, USA
Department, Miami VA Healthcare System, Miami, FL, USA
cDepartment
of Mechanical Engineering, University of Washington, Seattle, WA
dRehabilitation
Research and Development, VA Puget Sound Health Care System, Seattle, WA
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Corresponding author: Sheila M. Clemens, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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bResearch
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Glenn K. Klute, PhD Veterans Administration Puget Sound Health Care System 1660 S. Columbian Way Seattle, WA 98108 Email: [email protected] (206) 277-6724
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Neva J. Kirk-Sanchez, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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Michele A. Raya, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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Kyoung Jae Kim, PhD Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305)284-1272
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Robert S. Gailey, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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Ignacio A. Gaunaurd, PhD, PT Miami VA Health Care System 1201 N.W. 16th St. Miami, FL 33125 Email: [email protected] (305) 575-7000
Corresponding author:
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Sheila M. Clemens PhD, MPT, PT
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University of Miami Miller School of Medicine
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Department of Physical Therapy 5915 Ponce de Leon Blvd.
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Coral Gables, FL 33146 USA [email protected]
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HIGHLIGHTS:
Amputees perform turns differently depending on the direction of the turn.
Transfemoral and transtibial amputees exhibit distinct strategies for turning.
The cTUG is a clinically useful tool for assessing turns.
ABSTRACT:
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Background Daily ambulation with a prosthesis often involves turning to negotiate within the home and community environments, however how people with lower limb loss perform turns is infrequently studied. Administering a common clinical outcome measure to capture turn performance data provides a convenient means of assessing this ubiquitous activity.
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Research question
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What temporal-spatial parameters are exhibited by people with unilateral lower limb amputation
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while performing a 180˚ turn task?
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Methods
Forty community-ambulating subjects with unilateral lower limb amputation (20 transtibial
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amputees, 20 transfemoral amputees) performed the Component Timed-Up-and-Go (cTUG) test
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turning once in each direction, both toward the intact and toward the prosthetic limb. An
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instrumented walkway captured temporal-spatial parameters during performance of the 180˚ turn task of the cTUG, while a custom iPad application recorded time and number of steps to perform
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the turn. Comparisons between turn direction and level of amputation during the cTUG and temporal-spatial results were assessed.
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Results
People with lower limb amputation spent more time on their intact limb while turning than their prosthetic limb regardless of the position of the intact limb, and those with transfemoral amputation spent significantly more time over the intact limb than those with transtibial amputation.
Additionally, subjects with transfemoral amputation performed the turn significantly faster when turning with an inner intact limb. Significance
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Amputees use different movement strategies with altered temporal-spatial characteristics to turn depending on the direction of the turn and the level of amputation. Clinical use of the cTUG could provide evidence supporting prosthetic prescription practice and introduction of novel physical therapy interventions for individuals with lower limb amputation.
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Key words: lower limb amputation, outcome measures, turning, amputee mobility
1. Introduction
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The ability to negotiate around obstacles and change heading while walking is essential to household and community ambulation, as 35-45% of all steps taken during the day involve turning, with the number of turns increasing in more confined surroundings [1, 2]. Increased muscular demands are requisite during turning as the center of mass (CoM) is displaced over the inner stance foot in the direction of the turn [3-7]. The movement adaptations required for turning may pose
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difficulties to someone with motor impairment [8-10]. Difficulty with turning has been associated
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with increased fall risk and injury in the elderly [11-14]. Greater time and number of steps to
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perform a turn was found to be predictive of increased fall risk in elderly people with lower limb
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amputation (LLA) [15]. Previous research has determined that turning 180˚ is a complex mobility task that may expose balance impairments or mobility limitations that go undetected during linear
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gait [8, 11].
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Spin turns and step turns are the two most common types of turns [16], with step turns
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occurring more frequently during everyday activity [1]. During a spin turn, the body weight is supported over the metatarsophalangeal joint of the stance foot as the body rotates during the
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change of direction. A step turn differs because the change of direction is accomplished by both feet continuing to step, resulting in a wider base of support (BoS) [16]. With a wider BoS and
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slower angular velocities during a step turn [6], the CoM oscillates more between the inner and outer feet [5] as opposed to being maintained over the inner foot as during a spin turn [6]. This results in reduced muscular demands compared to a spin turn, making a step turn easier and more stable to perform [6, 16].
Turning is a motor task that results in asymmetrical temporal-spatial values. For a turn trajectory to occur, time spent on the inner limb of the turn increases, concomitantly time spent on the outer limb decreases [17-19]. The opposite is true of stride length, where the inner limb stride
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is shortened compared to the outer stride in order for the turn trajectory to occur [5, 20]. Additionally, velocity of each limb is different than during straight path walking; the outer demonstrates increased velocity compared to the inner limb [20]. Despite the high occurrence of turning during daily activity, the temporal-spatial parameters associated with turning, and the relationship to clinical assessment measures, have not been well examined in people with LLA.
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The purpose of this study was to determine the differences between the temporal-spatial
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parameters of the prosthetic and intact limb in people with unilateral LLA during the 180˚ turn
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task of the Component Timed-Up-and-Go test (cTUG) [21]. Differences in temporal-spatial values
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were expected when the 180˚ turn is performed with a prosthetic inner limb (PIL) compared to an intact inner limb (IIL), and differences based on amputation level, at either the transtibial (TT) or
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transfemoral (TF) level, would exist. The cTUG was administered as it allows for the assessment
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of different components of basic prosthetic mobility, specifically isolating the 180˚ turn.
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2. Method 2.1 Participants
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A convenience sample of 40 community ambulating people with LLA was recruited during a national amputee conference. This was a cross-sectional study approved by the internal review
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board (IRB) of the local veterans’ health care system. Functional mobility status was assigned to each subject by an on-site prosthetist, based on the widely-accepted Medicare Functional Classification Levels, or K-levels [22]. People were included if they were between 18-80 years old, had a unilateral TT or TF amputation for non-vascular reasons, had been using their prosthesis
for at least three months, and reported being comfortable in their socket. Participants who presented with open wounds, any amputation on the contralateral lower limb, or required more than a standard cane for independent transfers and ambulation were excluded from this sample.
Subjects
completed
questionnaires
regarding
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2.2 Procedure and data acquisition demographic
information,
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anthropometric measurements were documented (i.e. height, weight, waist circumference, and lower limb segment lengths). The cTUG was then administered. The cTUG was performed over the Zeno walkway. Temporal-spatial parameters of turning were captured using a 1.2m wide by
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4.3 m long Zeno Electronic Walkway system, Model Z4X14, and raw data was processed by
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Protokinetics Motion Analysis Software (Protokinetics LLC, Havertown,PA), which has exhibited
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validity in measuring temporal-spatial gait parameters [23]. The Zeno walkway sampled at 120
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Hz, and has a spatial resolution of 1.27 cm. A standard 3m TUG course was set up with three delineations (tapelines on the walking surface) on the walkway to indicate where each component
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task would be recorded. To standardize the turn, a cone, with a 10 cm diameter, was placed 3m
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from the center of the front legs of the chair. The cone also was used to illicit performance of a
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step turn by the subjects since it is the most common type of turn performed in daily mobility.[1] Additionally, the cone functioned to limit confusion as to where to perform the turn since this can
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introduce variability into the test [24-26]. The direction in which the turn was performed was randomized. The 180° turn time was recorded as subjects performed it in the delineated area
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(Figure 1). A custom mobile application was used to capture all cTUG performance data. An inapplication timer was initiated manually by the study therapist when the subject’s foot was observed breaking the plane of the tape line leading into the turn, and stopped as the plane was broken upon exiting the turn. An in-application video camera on the iPad allowed for visual
recording of the cTUG performance and counting of the number of steps to perform the 180˚ turn. Subjects were asked to perform the cTUG twice, once walking clockwise and once counterclockwise around the cone at their self-selected walking speed to capture turning with both
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a prosthetic PIL and IIL [21]. The cTUG variables of total time, and time and number of steps to perform the 180˚ turn were recorded. All study data was directly uploaded to a secure mainframe server at a university computational sciences center to allow for data processing. 2.3 Data analysis
Data from the Zeno mat was exported to Excel spreadsheets for processing. Temporal-
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spatial variables included: single limb stance as a percentage of gait cycle time (SLS%); total
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double limb stance as a percentage of gait cycle time (DLS%); stride length; limb velocity; and
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turning angular velocity. Gait cycle time (GCT) is defined as the time from the first contact of one
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foot, to the subsequent first contact of the same foot. Each foot has a period of initial DLS where it is the leading limb of a stride, followed by a period of SLS, then a period of terminal DLS where
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it is the trailing limb of the stride. SLS% was the variable of interest, as opposed to total stance
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time percentage, to avoid masking of balance deficits by the contribution of the contralateral leg
by 100.
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during stance. DLS% is the sum of initial DLS and terminal DLS, divided by GCT and multiplied
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The Protokinetics system measures spatial parameters for turning based on the established protocol of Huxham et al. [27]. Stride length was measured as the distance from the heel of one
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foot to the heel of the same foot on the following step. The result was subsequently divided by the subject’s height to normalize the measurement across body height and anatomical limb length. 2.4 Statistical Analysis
Normality was determined using visual inspection of Quantile-Quantile (QQ) plots and histograms. Descriptive statistics were computed for the sample population. Independent t-tests were used for between groups comparisons of TT and TF amputees. Paired t-tests were used to
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examine differences within the groups of subjects based on level of amputation. Bonferroni adjustments were employed where there were multiple comparisons to protect against type I error, an adjusted value of p≤ .013 was utilized to determine significance of these variables. Statistical analyses were performed using SAS 9.3 (SAS Institute Inc., Cary, NC, USA). 3. Results
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Forty subjects were enrolled in the study. Subjects had a mean age of 47.9 ± 14.7 years,
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and mean time since amputation was 9.8 ± 10.9 years. Individuals recruited were community-
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ambulators, resulting in most subjects being categorized at the K3 level. Seven subjects were
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classified as K2 level ambulators, 32 people classified as K3 level ambulators, and one subject classified as a K4 level ambulator. None of the subjects required an assistive device for ambulation.
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Subject characteristics by amputation level are presented in Table 1.
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Comparisons of the cTUG variables (i.e., total time, time and number of steps to perform
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the 180˚ turning task) were made contrasting performance with a PIL to a IIL. The only significant differences (p=.05) within the groups was that TF amputees performed the
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180˚ turn slower with a PIL (Table 2). Within group comparisons of temporal-spatial variables are presented in Tables 3 and 4.
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As anticipated, there was a 20-23% (p<.001) shorter stride length for the inner limb when compared to outer limb in both groups, regardless of the direction of the turn in both cohorts. As expected, the outer limb had significantly faster velocity than the inner limb regardless of turn
direction. Of interest is the finding that people with TF amputation exhibited a faster turning velocity when turning towards the IIL compared to the PIL (p=.02). Comparisons of variables between groups based on level of amputation are presented in
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Table 5. There were no differences between the TT or TF amputees regarding cTUG variables of total time, turn time, or number of steps. SLS% on an IIL was significantly longer (p<.001) in the TF amputee group than the TT amputee group (43.4 ± 4.2% and 35.5 ± 4.1%, respectively). This affected the amount of time those with TF amputation spent on their outer limb, resulting in significantly less SLS% (p<.001) spent on a POL (23.7 ± 3.2%) than people with TT amputation
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(28.4 ± 2.6%). Additionally, those with TF amputation spent a significantly greater SLS% on an
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IOL (p=.002) compared to those with TT amputation (38.3 ± 4.3% and 34.6 ± 3.0%, respectively).
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These results indicate that people with TF amputation spend significantly less time over their
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prosthetic limb than the intact limb, regardless of the direction of the turn and compared to those with TT amputation.
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4. Discussion
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Examining the turning characteristics of people with unilateral LLA provides insight into
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factors that affect stability and efficiency during daily turn activities. In studies of non-amputee individuals, it is consistently observed that more time is spent on the inner limb of the turn to
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maintain balance as the COM is propelled in the direction of the turn [3, 5, 19, 20]. The present study demonstrates that community ambulating people with unilateral LLA perform a 180˚ turn
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using differing strategies, dependent on whether the prosthetic limb or the intact limb is the inner limb of the turn, exposing adaptations prosthetic users employ during gait. Further differences were found between level of amputation, providing evidence that greater loss of muscle, bone, and joints may influence turn performance.
No differences were found in cTUG performance times when comparing the TT and TF amputee groups, likely do to the small sample sizes and generally high functional levels of the subjects. However, when examining within-groups, differences were exposed. People with TF
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amputation turned faster when turning with an IIL compared to a PIL. A moderate effect size (Cohen’s d=.48) was associated with this difference. This finding could be attributed to strength, balance, and somatosensory impairments due to more proximal amputation level [28]. Additionally, superfluous movement between the residual limb and prosthetic socket interface can be problematic for some LLAs [29, 30, 31]. People with TF amputation require more time during
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early stance to create a closed kinetic chain within the prosthetic socket to establish postural
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stability over the prosthesis. Greater soft tissue excursion within the socket during ambulation can
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be attributed to larger amount of muscle and adipose tissue of the thigh region [32]. Difficulties
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with socket stabilization, motor control, and the absence of the anatomical knee can contribute to balance impairments with a TF prosthetic limb [33] during turning, resulting in more time to
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complete the turn. The clinical utility of this difference with regard to turn direction may be better
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determined with a larger more heterogeneous sample size.
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Regardless of turn direction, significant differences were found in temporal-spatial parameters during turning. When examining the inner limb during turns, subjects with LLA spent
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less time over a PIL in contrast to literature on turning in the able-bodied population [19, 20]. Courtine et al [4], found that the larger percentage of time spent in stance over the inner limb, the
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closer the pelvis was to the stance foot, indicating a translation of the CoM over the inner limb of the turn. Differences were found in SLS% between the PIL and IIL indicating that subjects had difficulty displacing their COM over a PIL due to altered neuromuscular or balance capabilities. Balance confidence has been found to be moderately related to turning ability in people with LLA
[21], and impairments in balance confidence could be reflective of the inability to effectively translate the CoM over a PIL during a turn. Though all subjects spent less time over a PIL while turning, people with TF amputation
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spent significantly less time than those with TT amputation. Conversely, with an IIL, subjects with TF amputation spent significantly more time over that limb than the TT amputee cohort. The resulting large effect size (Cohen’s d=1.9) suggests that the time spent on the IIL, based on amputation level, may be reflected in the mobility differences often observed between TT and TF amputees. Turning is modulated by ground reaction forces in the medial-lateral direction [5], and
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people with TT amputation can manage perturbations in this direction as well as able-bodied
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individuals due to their intact hip musculature and knee joint [34]. Therefore, it may be posited
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that people with TF amputation are overcompensating with the intact limb during turning due to
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the additional loss of joint, bone, and muscle tissue beyond that of someone with TT amputation, resulting in different movement strategies to accomplish the turn. This overuse of the intact limb
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during mobility could lead to future secondary health issues [35, 36]. Providing targeted prosthetic
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training, to include motor control and balance activities during turning could positively affect how
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someone with LLA utilizes their prosthesis, resulting in better prosthetic stability, mobility, and improved quality of life.
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As expected, stride length measurements resulted in evidence of a shortened inner versus outer stride regardless of turn direction for all subjects. This aligns with previous research on
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turning, in that for a turn trajectory to occur, stride lengths must be asymmetrical [5, 20]. In agreement with a study by Segal et al [37], the current study found no difference in inner stride lengths of people with TT amputation when intact and prosthetic limbs were compared. In contrast,
turning has not been closely examined in the TF amputee population, and continued research may reveal further differences in strategies employed by this group. Few studies compare inner and outer limb velocities within subjects, and no studies involve
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people with LLA. Stride velocity of both TT and TF amputee groups was consistent with previous turning research in able-bodied subjects [20], where the outer limb’s velocity was significantly faster than that of the inner limb, regardless of turn direction. When turn angular velocity was examined, the TT amputee cohort showed no statistically significant difference in the speed at which they turned regardless of which limb was the inner limb, however people with TF
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amputation presented with a slower velocity while turning with a PIL. This finding supports the
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previously reported findings of this study that indicate that subjects with TF amputation require
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more time to perform a 180˚ step turn with a PIL. Again, the potential for movement deficits due
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to a more proximal amputation level cannot be discounted. Previous research has shown that the number of remaining lower limb joints is predictive of high-level mobility in amputee
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servicemembers [38], and it is plausible that this same exposure variable similarly affects a more
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5. Conclusion
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basic, yet challenging, mobility task like turning.
Turning is an understudied subset of walking, however with its ubiquitous presence in daily
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mobility, research describing turning characteristics and the variations between different diagnoses is important. This study reveals that community ambulating people with unilateral LLA perform a
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180˚ turning task differently depending on the direction of the turn with respect to the prosthetic limb, exhibiting a greater reliance on the intact limb regardless of turn direction. Additionally, those with TF amputation demonstrate a dependence on the intact limb more than people with TT amputation, indicating that amputee turning strategies vary depending on level of amputation. This
information could influence future research on turning and clinical practice regarding the treatment of people with LLA. 6. Clinical Perspectives
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The findings of this study provide a basis for continued investigation into common turning tasks in people with LLA, with the potential to develop targeted rehabilitation interventions to reduce overuse of the intact limb, and design new prostheses that may facilitate turn performance and enhance safety. 7. Study Limitations
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Because subjects were community ambulators, most of the subjects recruited presented
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with a non-vascular cause of amputation. The generalizability of the results will be further
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investigated in future studies. Expanding investigations to include people with dysvascular cause
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of amputation, and those at lower mobility levels could provide clinically relevant knowledge on how turning is accomplished in these sub-populations, indicating their mobility might be improved
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Conflict of Interest
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with different prosthetic prescriptions or physical therapy interventions.
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No conflicts of interest to report. Acknowledgements
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The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding for this research was provided by the United States
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Department of Defense (DOD)- Veterans Affairs (VA) Joint Incentive Fund (JIF).
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sound limb to balance control in unilateral transtibial amputees. Gait Posture. 2012;36(2):276-81.
osteopenia in British male war veterans with major lower limb amputations. Clin Rehabil.
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1998;12(4):348-53. 36.
Gailey RS, Allen K, Castles J, Kucharik J, Roeder M. Secondary physical conditions
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associated with lower limb amputation and long term prosthetic use. J Rehabil Res Dev. 2008;45(1):15-30. 37.
Segal AD, Orendurff MS, Czerniecki JM, Klute GK. Comparison of transtibial amputee
and non-amputee biomechanics during a common turning task. Gait Posture. 2011;33(1):41-7.
38.
Gaunaurd IA, Roach KE, Raya MA, Cooper R, Linberg A, Laferrier J, et al. Factors related
to high-level mobility in male servicemembers with traumatic lower-limb loss. J Rehabil Res Dev.
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2013;50(7):969-84.
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Figure 1. Set up of Component Timed-Up-and-Go test (cTUG).
Table 1. Descriptive characteristics of subjects (n=40). Variable
TT amputee cohort (n=20) Frequency (%)
TF amputee cohort (n=20) Frequency (%)
8 (40) 12 (60)
13 (65) 7 (35)
13 (65) 7 (35) Mean (SD) [Range] 53.4 (11.2) [36.3-72.6] 8.6 (7.1) [0.4-25.2] 173 (7.7) [158-188]
7 (35) 13 (65) Mean (SD) [Range] 42.5 (16.1) [19.1-73.9] 10.9 (13.7) [0.3-47.5] 175.6 (10) [149.7-189.9]
Male Female Side of amputation Right Left Age (y) Time since amputation (y) Height (cm)
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Gender
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Note: y=years, cm=centimeters.
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Table 2. Within group comparisons of direction of cTUG performance in transtibial and transfemoral amputee cohorts. Performance toward intact inner limb Mean (SD) [Range] 11.1 (2.1) [8.2-16.5] 3.0 (0.6) [2.2-4.3] 5 [4-8] 11.6 (2.1) [9.0-15.7] 3.0 (0.6) [2.2-4.2] 5 [4-8]
p value
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Performance toward prosthetic inner limb Mean (SD) [Range] TT amputee cohort (n=20) Total time (s) 11.2 (2.1) [8.6-16.8] Time for turn (s) 2.9 (0.7) [2.3-4.5] No. steps for turn 5 [4-8] TF amputee cohort (n=20) Total time (s) 11.5 (1.9) [8.9-14.8] Time for turn (s) 3.1 (0.5) [2.4-4.2] No. steps for turn 6 [4-8]
.22 .37 1.0
.60
.05*
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cTUG performance variable
.14
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Note: cTUG=Component Timed-Up-and-Go test. No.=number, s= seconds. Number of steps is presented as the median. *indicates significant finding, p≤ .05.
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Table 3. Within group comparisons of temporal-spatial variables during the 180˚ turn of the cTUG for the transtibial amputee cohort (n=20). TemporalSpatial Variable
PIL Mean (SD) [Range]
IOL Mean (SD) [Range]
IIL Mean (SD) [Range]
POL Mean [Range]
(SD)
p (POL vs. IOL)
p (POL vs. IIL)
p (PIL vs. IOL)
30.3 (2.9) 34.6 (3.0) 35.5 (4.1) 28.4 (2.6) <.001* <.001* <.001* <.001* [24.4-34.4] [27.2-41.3] [27.8-42.2] [23.0-34.0] DLS (%) 35.1 (5.0) 34.9 (5.0) 35.6 (5.4) 35.4 (5.6) .52 .35 .54 .50 [23.4-45.6] [23.7-44.5] [27.9-47.8] [26.4-47.2] Stride length 0.5 (0.1) 0.6 (0.1) 0.5 (0.1) 0.6 (0.1) .07 .87 <.001* <.001* [33.0-0.6] [0.4-0.7] [0.3-0.6] [0.4-0.7] Velocity (cm/s) 70.2 (13.9) 84.8 (11.4) 66.7 (13.5) 86.7 (12.8) .05 .15 <.001* <.001* [46.5-94.3] [59.4-100.9] [38.8-85.0] [60.4-104.0] Turn angular 64.2 (12.2) 62.6 (11.1) .30 velocity (˚/s) [39.7-78.3] [41.5-81.4] Note: cTUG=Component Timed-Up-and-Go test. PIL=prosthetic inner limb, IIL=intact inner limb, POL=prosthetic outer limb, IOL=intact outer limb. SLS%=percentage of time in single limb stance, DLS%=percentage of time in total double limb stance. cm=centimeter, s=second. Stride length normalized to height (non-dimensional value). *indicates significant finding, p≤ .013.
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SLS (%)
p (PIL vs. IIL)
24 Table 4. Within group comparisons of temporal-spatial variables during the 180˚ turn of the cTUG for the transfemoral amputee cohort (n=20). TemporalSpatial Variable
PIL Mean (SD) [Range]
IOL Mean (SD) [Range]
IIL Mean (SD) [Range]
POL Mean [Range]
(SD)
p (PIL vs. IIL)
p (POL vs. IOL)
p (POL vs. IIL)
p (PIL vs. IOL)
27.2 (3.7) 38.3 (4.3) 43.4 (4.2) 23.7 (3.2) <.001* <.001* <.001* <.001* [19.4-33] [33.7-51.1] [37.6-55.4) [18.3-31.3] DLS (%) 32.5 (6.0) 33.0 (4.9) 32.0 (6.6) 33.0 (4.7) .71 .51 .14 .85 [16.2-39.5] [24-41] [15-40.8] [23.9-39.8] Stride length .46 (.1) .6 (.06) .49 (.08) .6 (.07) .05 .68 <.001* <.001* [.28-.59] [.48-.7] [.37-.65] [.47-.7] Velocity 65.3 (14.9) 85.4 (10.5) 69.2 (12.3) 82.9 (12) .13 .14 <.001* <.001* (cm/s) [41.2-87.5] [70.9-102.3] [48.7-93.7] [60.4-104] Turn angular 58.9 (9.7) 62.0 (12.0) .02** velocity (˚/s) [43.3-74.7] [42.7-81.1] Note: cTUG=Component Timed-Up-and-Go test. PIL=prosthetic inner limb, IIL=intact inner limb, POL=prosthetic outer limb, IOL=intact outer limb. SLS%=percentage of time in single limb stance, DLS%=percentage of time in total double limb stance. cm=centimeter, s=second. Stride length normalized to height (non-dimensional value). *indicates significant finding at p≤ .013. **indicates significant finding at p≤ .05.
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25 Table 5. Between groups comparisons of temporal-spatial variables during the 180˚ turn of the cTUG based on level of amputation. Variable
TT amputee group (n=20) Mean (SD) [range] 53.4 (11.2) [36.3-72.6] 8.6 (7.1) [0.4-25.2]
TF amputee group (n=20) Mean (SD) [range] 42.5 (16.1) [19.1-73.9] 10.9 (13.7) [0.3-47.5]
p value
11.2 (2.1) [8.6-16.8] 11.1 (2.1) [8.2-16.5] 2.9 (.7) [2.3-4.5] 3.0 (.6) [2.2-4.3] 5 [4-8] 5 [4-8]
11.5 (1.9) [8.9-14.8] 11.6 (2.1) [9.0-15.7] 3.1 (0.5) [2.4-4.2] 3.0 (.6) [2.2-4.2] 6 [4-8] 5 [4-8]
.68
SLS on PIL (%)
30.3 (2.9) [24.4-34.4]
27.2 (3.7) [19.4-33.0]
SLS on IIL (%)
35.5 (4.1) [27.8-42.2]
43.4 (4.2) [37.6-55.4)
SLS on IOL (%)
34.6 (3.0) [27.2-41.3]
38.3 (4.3) [33.7-51.1]
SLS on POL (%)
28.4 (2.6) [23.0-34.0]
23.7 (3.2) [18.3-31.3]
<.001*
DLS on PIL (%)
35.1 (5.0) [23.4-45.6]
32.5 (6.0) [16.2-39.5]
.13
DLS on IIL (%)
35.6 (5.4) [27.9-47.8]
32.0 (6.6) [15-40.8]
.12
DLS on IOL (%)
34.9 (5.0) [23.7-44.5]
33.0 (4.9) [24.0-41.0]
.12
DLS on POL (%)
35.4 (5.6) [26.4-47.2]
33.0 (4.7) [23.9-39.8]
.14
0.5 (0.1) [33.0-0.6]
0.5 (0.1) [0.3-0.6]
.30
0.5 (0.1) [0.3-0.6]
0.5 (0.1) [0.4-0.7]
.22
0.6 (0.1) [0.4-0.7]
0.6 (0.1) [0.5-0.7]
.90
0.6 (0.1) [0.4-0.7]
0.6 (0.1) [0.5-0.7]
.90
Velocity of PIL (cm/s)
70.2 (13.9) [46.5-94.3]
65.3 (14.9) [41.2-87.5]
.29
Velocity of IIL (cm/s)
66.7 (13.5) [38.8-85.0]
69.2 (12.3) [48.7-93.7]
.54
Velocity of POL
86.7 (12.8) [60.4-104.0]
82.9 (12.0) [60.4-104.0]
.33
Velocity of IOL
84.8 (11.4) [59.4-100.9]
85.4 (10.5) [70.9-102.3]
.90
Turn angular velocity toward PIL
64.2 (12.2) [39.7-78.3]
58.9 (9.7) [43.3-74.7]
.13
Turn angular velocity toward IIL
62.6 (11.1) [41.5-81.4]
62.0 (12.0) [42.7-81.1]
.90
Age (y) Time since amputation (y)
.01* .50
Total time toward PIL Total time toward IIL Time for 180˚ turn toward PIL Time for 180˚ turn toward IIL No. steps to turn toward PIL No. steps to turn toward IIL
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cTUG performance
.50 .25 .86 .60 .77
Stride of POL
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Stride of IOL
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.006*
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Stride of IIL
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Stride of PIL
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Temporal-spatial turning variables
<.001* .002*
Note: Note: y= years. TT=transtibial, TF=transfemoral. PIL=prosthetic inner limb, IIL=intact inner limb, POL=prosthetic outer limb, IOL=intact outer limb. No.=number. Number of steps is presented as the median. SLS%=percentage of time in single limb stance, DLS%=percentage of time in total double limb stance. cm/s=centimeter per second. Stride length normalized to height (non-dimensional value). *indicates significant finding, p≤ .05.
S0966-6362(18)30553-8 https://doi.org/10.1016/j.gaitpost.2018.05.016 GAIPOS 6098
To appear in:
Gait & Posture
Received date: Revised date: Accepted date:
21-2-2018 2-5-2018 10-5-2018
Please cite this article as: Clemens SM, Klute GK, Kirk-Sanchez NJ, Raya MA, Kim KJ, Gaunaurd IA, Gailey RS, Temporal-Spatial Values during a 180◦ Step Turn in People with Unilateral Lower Limb Amputation, Gait and Posture (2010), https://doi.org/10.1016/j.gaitpost.2018.05.016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Manuscript Title: Temporal-Spatial Values during a 180 ˚ Step Turn in People with Unilateral Lower Limb Amputation Authors: Sheila M. Clemensa,b, Glenn K. Klutec,d, Neva J. Kirk-Sancheza, Michele A. Rayaa, Kyoung Jae Kima, Ignacio A. Gaunaurda,b, Robert S. Gaileya,b
aDepartment
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Institutions: of Physical Therapy, Miller School of Medicine, University of Miami, Coral Gables,
FL, USA
Department, Miami VA Healthcare System, Miami, FL, USA
cDepartment
of Mechanical Engineering, University of Washington, Seattle, WA
dRehabilitation
Research and Development, VA Puget Sound Health Care System, Seattle, WA
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Corresponding author: Sheila M. Clemens, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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bResearch
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Glenn K. Klute, PhD Veterans Administration Puget Sound Health Care System 1660 S. Columbian Way Seattle, WA 98108 Email: [email protected] (206) 277-6724
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Neva J. Kirk-Sanchez, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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Michele A. Raya, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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Kyoung Jae Kim, PhD Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305)284-1272
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Robert S. Gailey, PhD, PT Department of Physical Therapy, Miller School of Medicine University of Miami 5915 Ponce de Leon Blvd. Coral Gables, FL 33146 Email: [email protected] (305) 284-4535
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Ignacio A. Gaunaurd, PhD, PT Miami VA Health Care System 1201 N.W. 16th St. Miami, FL 33125 Email: [email protected] (305) 575-7000
Corresponding author:
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Sheila M. Clemens PhD, MPT, PT
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University of Miami Miller School of Medicine
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Department of Physical Therapy 5915 Ponce de Leon Blvd.
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Coral Gables, FL 33146 USA [email protected]
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HIGHLIGHTS:
Amputees perform turns differently depending on the direction of the turn.
Transfemoral and transtibial amputees exhibit distinct strategies for turning.
The cTUG is a clinically useful tool for assessing turns.
ABSTRACT:
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Background Daily ambulation with a prosthesis often involves turning to negotiate within the home and community environments, however how people with lower limb loss perform turns is infrequently studied. Administering a common clinical outcome measure to capture turn performance data provides a convenient means of assessing this ubiquitous activity.
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Research question
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What temporal-spatial parameters are exhibited by people with unilateral lower limb amputation
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while performing a 180˚ turn task?
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Methods
Forty community-ambulating subjects with unilateral lower limb amputation (20 transtibial
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amputees, 20 transfemoral amputees) performed the Component Timed-Up-and-Go (cTUG) test
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turning once in each direction, both toward the intact and toward the prosthetic limb. An
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instrumented walkway captured temporal-spatial parameters during performance of the 180˚ turn task of the cTUG, while a custom iPad application recorded time and number of steps to perform
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the turn. Comparisons between turn direction and level of amputation during the cTUG and temporal-spatial results were assessed.
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Results
People with lower limb amputation spent more time on their intact limb while turning than their prosthetic limb regardless of the position of the intact limb, and those with transfemoral amputation spent significantly more time over the intact limb than those with transtibial amputation.
Additionally, subjects with transfemoral amputation performed the turn significantly faster when turning with an inner intact limb. Significance
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Amputees use different movement strategies with altered temporal-spatial characteristics to turn depending on the direction of the turn and the level of amputation. Clinical use of the cTUG could provide evidence supporting prosthetic prescription practice and introduction of novel physical therapy interventions for individuals with lower limb amputation.
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Key words: lower limb amputation, outcome measures, turning, amputee mobility
1. Introduction
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The ability to negotiate around obstacles and change heading while walking is essential to household and community ambulation, as 35-45% of all steps taken during the day involve turning, with the number of turns increasing in more confined surroundings [1, 2]. Increased muscular demands are requisite during turning as the center of mass (CoM) is displaced over the inner stance foot in the direction of the turn [3-7]. The movement adaptations required for turning may pose
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difficulties to someone with motor impairment [8-10]. Difficulty with turning has been associated
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with increased fall risk and injury in the elderly [11-14]. Greater time and number of steps to
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perform a turn was found to be predictive of increased fall risk in elderly people with lower limb
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amputation (LLA) [15]. Previous research has determined that turning 180˚ is a complex mobility task that may expose balance impairments or mobility limitations that go undetected during linear
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gait [8, 11].
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Spin turns and step turns are the two most common types of turns [16], with step turns
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occurring more frequently during everyday activity [1]. During a spin turn, the body weight is supported over the metatarsophalangeal joint of the stance foot as the body rotates during the
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change of direction. A step turn differs because the change of direction is accomplished by both feet continuing to step, resulting in a wider base of support (BoS) [16]. With a wider BoS and
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slower angular velocities during a step turn [6], the CoM oscillates more between the inner and outer feet [5] as opposed to being maintained over the inner foot as during a spin turn [6]. This results in reduced muscular demands compared to a spin turn, making a step turn easier and more stable to perform [6, 16].
Turning is a motor task that results in asymmetrical temporal-spatial values. For a turn trajectory to occur, time spent on the inner limb of the turn increases, concomitantly time spent on the outer limb decreases [17-19]. The opposite is true of stride length, where the inner limb stride
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is shortened compared to the outer stride in order for the turn trajectory to occur [5, 20]. Additionally, velocity of each limb is different than during straight path walking; the outer demonstrates increased velocity compared to the inner limb [20]. Despite the high occurrence of turning during daily activity, the temporal-spatial parameters associated with turning, and the relationship to clinical assessment measures, have not been well examined in people with LLA.
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The purpose of this study was to determine the differences between the temporal-spatial
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parameters of the prosthetic and intact limb in people with unilateral LLA during the 180˚ turn
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task of the Component Timed-Up-and-Go test (cTUG) [21]. Differences in temporal-spatial values
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were expected when the 180˚ turn is performed with a prosthetic inner limb (PIL) compared to an intact inner limb (IIL), and differences based on amputation level, at either the transtibial (TT) or
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transfemoral (TF) level, would exist. The cTUG was administered as it allows for the assessment
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of different components of basic prosthetic mobility, specifically isolating the 180˚ turn.
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2. Method 2.1 Participants
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A convenience sample of 40 community ambulating people with LLA was recruited during a national amputee conference. This was a cross-sectional study approved by the internal review
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board (IRB) of the local veterans’ health care system. Functional mobility status was assigned to each subject by an on-site prosthetist, based on the widely-accepted Medicare Functional Classification Levels, or K-levels [22]. People were included if they were between 18-80 years old, had a unilateral TT or TF amputation for non-vascular reasons, had been using their prosthesis
for at least three months, and reported being comfortable in their socket. Participants who presented with open wounds, any amputation on the contralateral lower limb, or required more than a standard cane for independent transfers and ambulation were excluded from this sample.
Subjects
completed
questionnaires
regarding
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2.2 Procedure and data acquisition demographic
information,
and
anthropometric measurements were documented (i.e. height, weight, waist circumference, and lower limb segment lengths). The cTUG was then administered. The cTUG was performed over the Zeno walkway. Temporal-spatial parameters of turning were captured using a 1.2m wide by
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4.3 m long Zeno Electronic Walkway system, Model Z4X14, and raw data was processed by
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Protokinetics Motion Analysis Software (Protokinetics LLC, Havertown,PA), which has exhibited
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validity in measuring temporal-spatial gait parameters [23]. The Zeno walkway sampled at 120
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Hz, and has a spatial resolution of 1.27 cm. A standard 3m TUG course was set up with three delineations (tapelines on the walking surface) on the walkway to indicate where each component
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task would be recorded. To standardize the turn, a cone, with a 10 cm diameter, was placed 3m
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from the center of the front legs of the chair. The cone also was used to illicit performance of a
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step turn by the subjects since it is the most common type of turn performed in daily mobility.[1] Additionally, the cone functioned to limit confusion as to where to perform the turn since this can
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introduce variability into the test [24-26]. The direction in which the turn was performed was randomized. The 180° turn time was recorded as subjects performed it in the delineated area
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(Figure 1). A custom mobile application was used to capture all cTUG performance data. An inapplication timer was initiated manually by the study therapist when the subject’s foot was observed breaking the plane of the tape line leading into the turn, and stopped as the plane was broken upon exiting the turn. An in-application video camera on the iPad allowed for visual
recording of the cTUG performance and counting of the number of steps to perform the 180˚ turn. Subjects were asked to perform the cTUG twice, once walking clockwise and once counterclockwise around the cone at their self-selected walking speed to capture turning with both
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a prosthetic PIL and IIL [21]. The cTUG variables of total time, and time and number of steps to perform the 180˚ turn were recorded. All study data was directly uploaded to a secure mainframe server at a university computational sciences center to allow for data processing. 2.3 Data analysis
Data from the Zeno mat was exported to Excel spreadsheets for processing. Temporal-
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spatial variables included: single limb stance as a percentage of gait cycle time (SLS%); total
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double limb stance as a percentage of gait cycle time (DLS%); stride length; limb velocity; and
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turning angular velocity. Gait cycle time (GCT) is defined as the time from the first contact of one
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foot, to the subsequent first contact of the same foot. Each foot has a period of initial DLS where it is the leading limb of a stride, followed by a period of SLS, then a period of terminal DLS where
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it is the trailing limb of the stride. SLS% was the variable of interest, as opposed to total stance
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time percentage, to avoid masking of balance deficits by the contribution of the contralateral leg
by 100.
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during stance. DLS% is the sum of initial DLS and terminal DLS, divided by GCT and multiplied
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The Protokinetics system measures spatial parameters for turning based on the established protocol of Huxham et al. [27]. Stride length was measured as the distance from the heel of one
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foot to the heel of the same foot on the following step. The result was subsequently divided by the subject’s height to normalize the measurement across body height and anatomical limb length. 2.4 Statistical Analysis
Normality was determined using visual inspection of Quantile-Quantile (QQ) plots and histograms. Descriptive statistics were computed for the sample population. Independent t-tests were used for between groups comparisons of TT and TF amputees. Paired t-tests were used to
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examine differences within the groups of subjects based on level of amputation. Bonferroni adjustments were employed where there were multiple comparisons to protect against type I error, an adjusted value of p≤ .013 was utilized to determine significance of these variables. Statistical analyses were performed using SAS 9.3 (SAS Institute Inc., Cary, NC, USA). 3. Results
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Forty subjects were enrolled in the study. Subjects had a mean age of 47.9 ± 14.7 years,
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and mean time since amputation was 9.8 ± 10.9 years. Individuals recruited were community-
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ambulators, resulting in most subjects being categorized at the K3 level. Seven subjects were
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classified as K2 level ambulators, 32 people classified as K3 level ambulators, and one subject classified as a K4 level ambulator. None of the subjects required an assistive device for ambulation.
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Subject characteristics by amputation level are presented in Table 1.
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Comparisons of the cTUG variables (i.e., total time, time and number of steps to perform
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the 180˚ turning task) were made contrasting performance with a PIL to a IIL. The only significant differences (p=.05) within the groups was that TF amputees performed the
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180˚ turn slower with a PIL (Table 2). Within group comparisons of temporal-spatial variables are presented in Tables 3 and 4.
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As anticipated, there was a 20-23% (p<.001) shorter stride length for the inner limb when compared to outer limb in both groups, regardless of the direction of the turn in both cohorts. As expected, the outer limb had significantly faster velocity than the inner limb regardless of turn
direction. Of interest is the finding that people with TF amputation exhibited a faster turning velocity when turning towards the IIL compared to the PIL (p=.02). Comparisons of variables between groups based on level of amputation are presented in
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Table 5. There were no differences between the TT or TF amputees regarding cTUG variables of total time, turn time, or number of steps. SLS% on an IIL was significantly longer (p<.001) in the TF amputee group than the TT amputee group (43.4 ± 4.2% and 35.5 ± 4.1%, respectively). This affected the amount of time those with TF amputation spent on their outer limb, resulting in significantly less SLS% (p<.001) spent on a POL (23.7 ± 3.2%) than people with TT amputation
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(28.4 ± 2.6%). Additionally, those with TF amputation spent a significantly greater SLS% on an
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IOL (p=.002) compared to those with TT amputation (38.3 ± 4.3% and 34.6 ± 3.0%, respectively).
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These results indicate that people with TF amputation spend significantly less time over their
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prosthetic limb than the intact limb, regardless of the direction of the turn and compared to those with TT amputation.
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4. Discussion
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Examining the turning characteristics of people with unilateral LLA provides insight into
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factors that affect stability and efficiency during daily turn activities. In studies of non-amputee individuals, it is consistently observed that more time is spent on the inner limb of the turn to
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maintain balance as the COM is propelled in the direction of the turn [3, 5, 19, 20]. The present study demonstrates that community ambulating people with unilateral LLA perform a 180˚ turn
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using differing strategies, dependent on whether the prosthetic limb or the intact limb is the inner limb of the turn, exposing adaptations prosthetic users employ during gait. Further differences were found between level of amputation, providing evidence that greater loss of muscle, bone, and joints may influence turn performance.
No differences were found in cTUG performance times when comparing the TT and TF amputee groups, likely do to the small sample sizes and generally high functional levels of the subjects. However, when examining within-groups, differences were exposed. People with TF
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amputation turned faster when turning with an IIL compared to a PIL. A moderate effect size (Cohen’s d=.48) was associated with this difference. This finding could be attributed to strength, balance, and somatosensory impairments due to more proximal amputation level [28]. Additionally, superfluous movement between the residual limb and prosthetic socket interface can be problematic for some LLAs [29, 30, 31]. People with TF amputation require more time during
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early stance to create a closed kinetic chain within the prosthetic socket to establish postural
N
stability over the prosthesis. Greater soft tissue excursion within the socket during ambulation can
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be attributed to larger amount of muscle and adipose tissue of the thigh region [32]. Difficulties
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with socket stabilization, motor control, and the absence of the anatomical knee can contribute to balance impairments with a TF prosthetic limb [33] during turning, resulting in more time to
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complete the turn. The clinical utility of this difference with regard to turn direction may be better
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determined with a larger more heterogeneous sample size.
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Regardless of turn direction, significant differences were found in temporal-spatial parameters during turning. When examining the inner limb during turns, subjects with LLA spent
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less time over a PIL in contrast to literature on turning in the able-bodied population [19, 20]. Courtine et al [4], found that the larger percentage of time spent in stance over the inner limb, the
A
closer the pelvis was to the stance foot, indicating a translation of the CoM over the inner limb of the turn. Differences were found in SLS% between the PIL and IIL indicating that subjects had difficulty displacing their COM over a PIL due to altered neuromuscular or balance capabilities. Balance confidence has been found to be moderately related to turning ability in people with LLA
[21], and impairments in balance confidence could be reflective of the inability to effectively translate the CoM over a PIL during a turn. Though all subjects spent less time over a PIL while turning, people with TF amputation
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spent significantly less time than those with TT amputation. Conversely, with an IIL, subjects with TF amputation spent significantly more time over that limb than the TT amputee cohort. The resulting large effect size (Cohen’s d=1.9) suggests that the time spent on the IIL, based on amputation level, may be reflected in the mobility differences often observed between TT and TF amputees. Turning is modulated by ground reaction forces in the medial-lateral direction [5], and
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people with TT amputation can manage perturbations in this direction as well as able-bodied
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individuals due to their intact hip musculature and knee joint [34]. Therefore, it may be posited
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that people with TF amputation are overcompensating with the intact limb during turning due to
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the additional loss of joint, bone, and muscle tissue beyond that of someone with TT amputation, resulting in different movement strategies to accomplish the turn. This overuse of the intact limb
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during mobility could lead to future secondary health issues [35, 36]. Providing targeted prosthetic
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training, to include motor control and balance activities during turning could positively affect how
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someone with LLA utilizes their prosthesis, resulting in better prosthetic stability, mobility, and improved quality of life.
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As expected, stride length measurements resulted in evidence of a shortened inner versus outer stride regardless of turn direction for all subjects. This aligns with previous research on
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turning, in that for a turn trajectory to occur, stride lengths must be asymmetrical [5, 20]. In agreement with a study by Segal et al [37], the current study found no difference in inner stride lengths of people with TT amputation when intact and prosthetic limbs were compared. In contrast,
turning has not been closely examined in the TF amputee population, and continued research may reveal further differences in strategies employed by this group. Few studies compare inner and outer limb velocities within subjects, and no studies involve
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people with LLA. Stride velocity of both TT and TF amputee groups was consistent with previous turning research in able-bodied subjects [20], where the outer limb’s velocity was significantly faster than that of the inner limb, regardless of turn direction. When turn angular velocity was examined, the TT amputee cohort showed no statistically significant difference in the speed at which they turned regardless of which limb was the inner limb, however people with TF
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amputation presented with a slower velocity while turning with a PIL. This finding supports the
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previously reported findings of this study that indicate that subjects with TF amputation require
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more time to perform a 180˚ step turn with a PIL. Again, the potential for movement deficits due
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to a more proximal amputation level cannot be discounted. Previous research has shown that the number of remaining lower limb joints is predictive of high-level mobility in amputee
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servicemembers [38], and it is plausible that this same exposure variable similarly affects a more
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5. Conclusion
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basic, yet challenging, mobility task like turning.
Turning is an understudied subset of walking, however with its ubiquitous presence in daily
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mobility, research describing turning characteristics and the variations between different diagnoses is important. This study reveals that community ambulating people with unilateral LLA perform a
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180˚ turning task differently depending on the direction of the turn with respect to the prosthetic limb, exhibiting a greater reliance on the intact limb regardless of turn direction. Additionally, those with TF amputation demonstrate a dependence on the intact limb more than people with TT amputation, indicating that amputee turning strategies vary depending on level of amputation. This
information could influence future research on turning and clinical practice regarding the treatment of people with LLA. 6. Clinical Perspectives
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The findings of this study provide a basis for continued investigation into common turning tasks in people with LLA, with the potential to develop targeted rehabilitation interventions to reduce overuse of the intact limb, and design new prostheses that may facilitate turn performance and enhance safety. 7. Study Limitations
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Because subjects were community ambulators, most of the subjects recruited presented
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with a non-vascular cause of amputation. The generalizability of the results will be further
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investigated in future studies. Expanding investigations to include people with dysvascular cause
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of amputation, and those at lower mobility levels could provide clinically relevant knowledge on how turning is accomplished in these sub-populations, indicating their mobility might be improved
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Conflict of Interest
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with different prosthetic prescriptions or physical therapy interventions.
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No conflicts of interest to report. Acknowledgements
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The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding for this research was provided by the United States
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Department of Defense (DOD)- Veterans Affairs (VA) Joint Incentive Fund (JIF).
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2013;50(7):969-84.
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Figure 1. Set up of Component Timed-Up-and-Go test (cTUG).
Table 1. Descriptive characteristics of subjects (n=40). Variable
TT amputee cohort (n=20) Frequency (%)
TF amputee cohort (n=20) Frequency (%)
8 (40) 12 (60)
13 (65) 7 (35)
13 (65) 7 (35) Mean (SD) [Range] 53.4 (11.2) [36.3-72.6] 8.6 (7.1) [0.4-25.2] 173 (7.7) [158-188]
7 (35) 13 (65) Mean (SD) [Range] 42.5 (16.1) [19.1-73.9] 10.9 (13.7) [0.3-47.5] 175.6 (10) [149.7-189.9]
Male Female Side of amputation Right Left Age (y) Time since amputation (y) Height (cm)
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Gender
A
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D
M
A
N
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Note: y=years, cm=centimeters.
22
Table 2. Within group comparisons of direction of cTUG performance in transtibial and transfemoral amputee cohorts. Performance toward intact inner limb Mean (SD) [Range] 11.1 (2.1) [8.2-16.5] 3.0 (0.6) [2.2-4.3] 5 [4-8] 11.6 (2.1) [9.0-15.7] 3.0 (0.6) [2.2-4.2] 5 [4-8]
p value
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Performance toward prosthetic inner limb Mean (SD) [Range] TT amputee cohort (n=20) Total time (s) 11.2 (2.1) [8.6-16.8] Time for turn (s) 2.9 (0.7) [2.3-4.5] No. steps for turn 5 [4-8] TF amputee cohort (n=20) Total time (s) 11.5 (1.9) [8.9-14.8] Time for turn (s) 3.1 (0.5) [2.4-4.2] No. steps for turn 6 [4-8]
.22 .37 1.0
.60
.05*
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cTUG performance variable
.14
A
CC
EP
TE
D
M
A
N
Note: cTUG=Component Timed-Up-and-Go test. No.=number, s= seconds. Number of steps is presented as the median. *indicates significant finding, p≤ .05.
23
Table 3. Within group comparisons of temporal-spatial variables during the 180˚ turn of the cTUG for the transtibial amputee cohort (n=20). TemporalSpatial Variable
PIL Mean (SD) [Range]
IOL Mean (SD) [Range]
IIL Mean (SD) [Range]
POL Mean [Range]
(SD)
p (POL vs. IOL)
p (POL vs. IIL)
p (PIL vs. IOL)
30.3 (2.9) 34.6 (3.0) 35.5 (4.1) 28.4 (2.6) <.001* <.001* <.001* <.001* [24.4-34.4] [27.2-41.3] [27.8-42.2] [23.0-34.0] DLS (%) 35.1 (5.0) 34.9 (5.0) 35.6 (5.4) 35.4 (5.6) .52 .35 .54 .50 [23.4-45.6] [23.7-44.5] [27.9-47.8] [26.4-47.2] Stride length 0.5 (0.1) 0.6 (0.1) 0.5 (0.1) 0.6 (0.1) .07 .87 <.001* <.001* [33.0-0.6] [0.4-0.7] [0.3-0.6] [0.4-0.7] Velocity (cm/s) 70.2 (13.9) 84.8 (11.4) 66.7 (13.5) 86.7 (12.8) .05 .15 <.001* <.001* [46.5-94.3] [59.4-100.9] [38.8-85.0] [60.4-104.0] Turn angular 64.2 (12.2) 62.6 (11.1) .30 velocity (˚/s) [39.7-78.3] [41.5-81.4] Note: cTUG=Component Timed-Up-and-Go test. PIL=prosthetic inner limb, IIL=intact inner limb, POL=prosthetic outer limb, IOL=intact outer limb. SLS%=percentage of time in single limb stance, DLS%=percentage of time in total double limb stance. cm=centimeter, s=second. Stride length normalized to height (non-dimensional value). *indicates significant finding, p≤ .013.
A
CC
EP
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D
M
A
N
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SLS (%)
p (PIL vs. IIL)
24 Table 4. Within group comparisons of temporal-spatial variables during the 180˚ turn of the cTUG for the transfemoral amputee cohort (n=20). TemporalSpatial Variable
PIL Mean (SD) [Range]
IOL Mean (SD) [Range]
IIL Mean (SD) [Range]
POL Mean [Range]
(SD)
p (PIL vs. IIL)
p (POL vs. IOL)
p (POL vs. IIL)
p (PIL vs. IOL)
27.2 (3.7) 38.3 (4.3) 43.4 (4.2) 23.7 (3.2) <.001* <.001* <.001* <.001* [19.4-33] [33.7-51.1] [37.6-55.4) [18.3-31.3] DLS (%) 32.5 (6.0) 33.0 (4.9) 32.0 (6.6) 33.0 (4.7) .71 .51 .14 .85 [16.2-39.5] [24-41] [15-40.8] [23.9-39.8] Stride length .46 (.1) .6 (.06) .49 (.08) .6 (.07) .05 .68 <.001* <.001* [.28-.59] [.48-.7] [.37-.65] [.47-.7] Velocity 65.3 (14.9) 85.4 (10.5) 69.2 (12.3) 82.9 (12) .13 .14 <.001* <.001* (cm/s) [41.2-87.5] [70.9-102.3] [48.7-93.7] [60.4-104] Turn angular 58.9 (9.7) 62.0 (12.0) .02** velocity (˚/s) [43.3-74.7] [42.7-81.1] Note: cTUG=Component Timed-Up-and-Go test. PIL=prosthetic inner limb, IIL=intact inner limb, POL=prosthetic outer limb, IOL=intact outer limb. SLS%=percentage of time in single limb stance, DLS%=percentage of time in total double limb stance. cm=centimeter, s=second. Stride length normalized to height (non-dimensional value). *indicates significant finding at p≤ .013. **indicates significant finding at p≤ .05.
A
CC
EP
TE
D
M
A
N
U
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SLS (%)
25 Table 5. Between groups comparisons of temporal-spatial variables during the 180˚ turn of the cTUG based on level of amputation. Variable
TT amputee group (n=20) Mean (SD) [range] 53.4 (11.2) [36.3-72.6] 8.6 (7.1) [0.4-25.2]
TF amputee group (n=20) Mean (SD) [range] 42.5 (16.1) [19.1-73.9] 10.9 (13.7) [0.3-47.5]
p value
11.2 (2.1) [8.6-16.8] 11.1 (2.1) [8.2-16.5] 2.9 (.7) [2.3-4.5] 3.0 (.6) [2.2-4.3] 5 [4-8] 5 [4-8]
11.5 (1.9) [8.9-14.8] 11.6 (2.1) [9.0-15.7] 3.1 (0.5) [2.4-4.2] 3.0 (.6) [2.2-4.2] 6 [4-8] 5 [4-8]
.68
SLS on PIL (%)
30.3 (2.9) [24.4-34.4]
27.2 (3.7) [19.4-33.0]
SLS on IIL (%)
35.5 (4.1) [27.8-42.2]
43.4 (4.2) [37.6-55.4)
SLS on IOL (%)
34.6 (3.0) [27.2-41.3]
38.3 (4.3) [33.7-51.1]
SLS on POL (%)
28.4 (2.6) [23.0-34.0]
23.7 (3.2) [18.3-31.3]
<.001*
DLS on PIL (%)
35.1 (5.0) [23.4-45.6]
32.5 (6.0) [16.2-39.5]
.13
DLS on IIL (%)
35.6 (5.4) [27.9-47.8]
32.0 (6.6) [15-40.8]
.12
DLS on IOL (%)
34.9 (5.0) [23.7-44.5]
33.0 (4.9) [24.0-41.0]
.12
DLS on POL (%)
35.4 (5.6) [26.4-47.2]
33.0 (4.7) [23.9-39.8]
.14
0.5 (0.1) [33.0-0.6]
0.5 (0.1) [0.3-0.6]
.30
0.5 (0.1) [0.3-0.6]
0.5 (0.1) [0.4-0.7]
.22
0.6 (0.1) [0.4-0.7]
0.6 (0.1) [0.5-0.7]
.90
0.6 (0.1) [0.4-0.7]
0.6 (0.1) [0.5-0.7]
.90
Velocity of PIL (cm/s)
70.2 (13.9) [46.5-94.3]
65.3 (14.9) [41.2-87.5]
.29
Velocity of IIL (cm/s)
66.7 (13.5) [38.8-85.0]
69.2 (12.3) [48.7-93.7]
.54
Velocity of POL
86.7 (12.8) [60.4-104.0]
82.9 (12.0) [60.4-104.0]
.33
Velocity of IOL
84.8 (11.4) [59.4-100.9]
85.4 (10.5) [70.9-102.3]
.90
Turn angular velocity toward PIL
64.2 (12.2) [39.7-78.3]
58.9 (9.7) [43.3-74.7]
.13
Turn angular velocity toward IIL
62.6 (11.1) [41.5-81.4]
62.0 (12.0) [42.7-81.1]
.90
Age (y) Time since amputation (y)
.01* .50
Total time toward PIL Total time toward IIL Time for 180˚ turn toward PIL Time for 180˚ turn toward IIL No. steps to turn toward PIL No. steps to turn toward IIL
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cTUG performance
.50 .25 .86 .60 .77
Stride of POL
A
CC
Stride of IOL
N
.006*
A
M D
TE
Stride of IIL
EP
Stride of PIL
U
Temporal-spatial turning variables
<.001* .002*
Note: Note: y= years. TT=transtibial, TF=transfemoral. PIL=prosthetic inner limb, IIL=intact inner limb, POL=prosthetic outer limb, IOL=intact outer limb. No.=number. Number of steps is presented as the median. SLS%=percentage of time in single limb stance, DLS%=percentage of time in total double limb stance. cm/s=centimeter per second. Stride length normalized to height (non-dimensional value). *indicates significant finding, p≤ .05.