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Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis
Journal Pre-proof Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis
Yannick Delpierre, Philippe Vernet, Annie Surdel PII:
S0268-0033(18)30990-2
DOI:
https://doi.org/10.1016/j.clinbiomech.2019.11.003
Reference:
JCLB 4895
To appear in:
Clinical Biomechanics
Received date:
27 November 2018
Accepted date:
8 November 2019
Please cite this article as: Y. Delpierre, P. Vernet and A. Surdel, Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis, Clinical Biomechanics (2019), https://doi.org/10.1016/j.clinbiomech.2019.11.003
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© 2019 Published by Elsevier.
Journal Pre-proof
Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis Yannick Delpierre(1), Philippe Vernet(1), Annie Surdel(1) (1) Laboratoire d’Analyse du Mouvement, Centre de l’Arche, Pole Régional du Handicap, 72650 St Saturnin – France; Corresponding author email: [email protected]
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Word count abstract: 248 words (/250). Total word count: 3000 (/3000)
Abstract
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Background: Scoliosis may have an effect on gait parameters, the kinematics of the
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lower limbs and the spine, and mechanical work with specific gait speed. Imposed gait
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speed may influence these effects. Following spinal fusion in the case of idiopathic scoliosis, patients fear subsequent and considerable back stiffness and kinetic
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consequences. The aim of this retrospective study was to evaluate the upper body range
conditions.
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of motion and mechanical work before and after spinal fusion in of free gait speed
Methods: Twenty-two patients with idiopathic scoliosis and twenty-two asymptomatic controls were included. Patients were analyzed before and one year after spinal fusion. Based on full body modeling and motion capture, we measured gait speed, cadence, stride length, the mobility of the upper and lower spinal segments (in each plane), and mechanical work (with and without dimensionless scaling strategy). Findings: Patients walked significantly slower than controls. The same speed was noticed before and after fusion. Only the lower back kinematics in the frontal plane was reduced before fusion. Spinal fusion further reduced the mobility of the pelvis segment
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Journal Pre-proof in the sagittal plane in comparison to controls. Scaling external work was associated with higher values for patients. Interpretation: Spinal fusion improves pelvic and thorax-pelvis mobility (during the stance phase) in the frontal plane. The impact of scoliosis on the upper body range of motion was limited on the thorax-pelvis, corresponding to a stiffening effect. With such restrictions, an increase in normalized external work was observed for similar normalized internal work.
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Keywords: scoliosis, gait analysis, spinal fusion, mechanical works, scaling quantity
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1. Introduction
Idiopathic Scoliosis (IS) is associated with three-dimensional deformity of the
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spine. This deformity has major repercussions related to cosmetic defect [11] and
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gait [1,4,6,9,14-15,18-20,26-27,29]. However, if brace treatment is ineffective in
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controlling the progression of scoliosis, spinal fusion may be an option to prevent further deterioration of the curve [18]. This surgery leads to back stiffness and reduces
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the spinal range of motion [9,15]. However, movements in the frontal pelvis (obliquity) and hips (abduction/adduction) are improved, in contrast to transversal shoulder motions (rotations) in the case of the thoracolumbar/lumbar primary structural curve, and are explained as stiffness in the counter-rotation between the two girdles, probably due to spine fusion [19]. The increase in hip and pelvic mobility in the frontal plane could be related to the need to compensate stiff girdle dissociation. The authors used kinematic data to describe this condition of stiffness under imposed constant gait speed. Here, stiffness represents an inability to move and walk as freely as healthy subjects. The long-term consequences of spinal fusion include frontal imbalance and a decrease of pelvic tilt in the sagittal plane under imposed gait speed [20].
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Journal Pre-proof The trunk and spine are not rigid segments but are made up of several segments. Arthrodesis can be considered by IS patients as a factor that increases spinal and trunk rigidities, reducing back mobility. This fear of lumbar stiffness or motion restrictions has an impact on activities of daily living [12]. Few studies have considered movements of the different segments that make up the trunk during gait [1,27]. Gait speed may impact the kinematic data of these different parts of the trunk [9,29], whereas spinal fusion does not modify self-selected speed [15].
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The first step in this analysis considers three principal segments of the back: thorax,
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thorax-pelvis and pelvis [9]. For each segment, the range of motion per plane allows
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quantifying the consequences of rigidity. It does not, however, give information on the
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efficiency of the locomotor mechanism. External work (Wext) corresponds to the mechanical work performed to move the Center of Mass (CoM). Internal work (Wint) is
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the work associated with the movements of each body segment. Mahaudens et al.
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presented demonstrated less mechanical work for IS patients with imposed speed (4 km h-1), but this speed could be considered as a biomechanical constraint in the case of
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spontaneously fast walkers [19]. Habitually, asymptomatic adolescents/young adults walked at a free gait speed around 1.17-1.6 m s-1 [4,13]. Minimizing the vertical motion of CoM in the case of gait speed reduction induces more metabolic energy consumption [24]. Thus, reducing walking speed could lead to an increase of Wext. Furthermore, in the case of patients with IS (before spinal fusion), several motion reductions have been observed on the lower limbs (like hip motion in the frontal and transversal planes), associated with reduced step length [14,27,29]. Joint motion restrictions on the lower limbs (in the case of adolescents with unilateral cerebral palsy) increase Wext [34]. Therefore, it seems possible to observe higher Wext in the case of patients with IS.
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Journal Pre-proof Finally, electrical activity was higher for all scoliosis groups [19]. Such results could be in phase with higher Wext or higher Wint. Wext and Wint vary as a function of gait speed. Therefore, is it preferable to impose speed (for instance with a treadmill, as described by Mahaudens et al. [19] or to apply free self-selected speed and compute the normalization of the work (based on the ratio between the anthropometric data of each patient and the asymptomatic population), as described by Hof [7,8]. The first solution assumes that the use of a treadmill has no
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effect on gait variables. The use of a treadmill to study the consequences of surgery may
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not be ideal for patients with poor individual balance performance and stability
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[3,10,30]. The second option requires the dimensionless scaling strategy [7,8].
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In the case of imposed-speed with a treadmill, the pelvis and structural spine changes are dependent. To our knowledge, no study has assessed the effect of surgery
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on pelvis mobility, spinal stiffness and the mechanical variables in self-selected speed
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condition and dimensionless scaling strategy. The aim of this study is to evaluate the incidence of scoliosis on gait in self-selected speed condition with regard to pelvis
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mobility (considering that pelvic motions in the frontal plane are sensitive to scoliosis and spinal fusion), and on the biomechanical stiffness of the trunk and mechanical work (with normalization), before and after spinal fusion. The hypotheses are:
1) Patients with IS improve their pelvic mobility in the frontal plane after spinal fusion in self-selected speed condition. 2) Biomechanical stiffness of the trunk (thorax and thorax-pelvis segments) distinguishes IS patients before spinal fusion from patients after spinal fusion. 3) Wext and Wint during gait are superior in IS patients (before spinal fusion) than in healthy population and spinal fusion tends to normality.
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Journal Pre-proof 2. Material and methodology 2.1 Subjects This
retrospective
study
was
approved
by
the
local
Ethical
Committee (no. 2017/08). All participants signed informed consent forms to use anonymous data. The study included a population consisting of twenty-two idiopathic scoliotic patients (before surgery: mean 16.9 years (Standard Deviation 3.1); height:
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mean 162.4 cm (SD 8.4); weight: mean 52.1 kg (SD 8.4 ); Cobb angle: mean 56.3° (SD 26.3); scoliosis oriented on right side; after surgery: mean 17.9 years (SD 3.1); height:
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mean 164 cm (SD 7.4); weight: mean 54.2 kg (SD 8.4); Cobb angle: mean 14.7° (SD
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14.6) and twenty-two control subjects (age: mean 18.5 years (SD 0.8); height: mean
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169.5 cm (SD 8.1); weight: mean 60.8 kg (SD 9.6 kg).
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The patients treated underwent surgery by the same orthopedic spine surgeon and were recruited among patients scheduled for spinal fusion between January 2008
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and December 2013. After surgery, all the patients followed an identical rehabilitation program. To avoid post-surgery discomfort and give patients time to restore their body
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image, movement analysis was performed two months preceding surgery and one year after spinal fusion. Analysis was included in the medical follow-up. Before surgery, standard bi-planar radiography was completed the same day as gait analysis. Cobbangles and Risser classification were determined for each patient based on radiographies.
Patients
were
excluded
if
they reported
mental
retardation,
musculoskeletal/neurological diseases, inequalities in leg length, locomotion injuries and previous surgical treatment of the spine. Healthy subjects were physical therapy students who did not suffer from musculoskeletal or neurological problems, scoliosis, inequalities in leg length, or obesity (>95th BMI per-age percentile).
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Journal Pre-proof 2.2 Data collection and data reduction Clinical gait analysis was performed using a motion capture system (VICON, Oxford Metrics, Oxford, UK, 100Hz) and 31 retro reflective spherical markers (14 mm) applied by a biomedical engineer with previous experience in this type of analysis. Both tools were used as part of the “Plug-in Gait Full Body” model. The software Nexus (version 1.8.5, Vicon, Oxford, UK) captured markers, defined gait events, and
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applied the model. These markers were placed directly on the skin at the following locations: bilateral shoulders (acromio-clavicular joint); bilateral elbows; bilateral
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wrists (radius-styloid process and ulna-styloid process); each hand (dorsum of the hand
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just below the medial head of metacarpal); the spinous process of the 7th cervical
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vertebra and 10th thoracic vertebra; bilateral anterior superior iliac spine (ASIS);
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sacrum (SACR), considered as the middle of the segment between posterior superior iliac spines; lateral tibial plateau; lateral malleoli; second metatarsal head; heel; lateral
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epicondyle of the femur; bilateral tibial wands; left and right femoral wands [5]. Therefore, the thorax was defined by the markers on C7, T10, sternum and clavicle
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(jugular notch). The pelvis was defined using markers on the two ASIS and SACR. Spatiotemporal gait data included gait speed, cadence and stride length. As proposed in [7], a normalized and non-dimensionless gait speed was computed. Two AMTI (MCA model) synchronized force platforms (1000 Hz) were located in the middle of the walking corridor. No specific instructions were given to subjects in relation to correctly placing their feet on each force platform to avoid perturbation on gait. Wext and Wint were computed and recorded in J kg-1 m-1 [2,22,31]. Wext corresponds to the dot product of the Ground Reaction Force and displacement of the CoM vectors as developed by Cavagna [2] and applied by Willems et al. [31]. Based on
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Journal Pre-proof F (the result of the external forces applied to the body), D (the displacement of CoM), Wext is given by: ⃗⃗ 𝑊𝑒𝑥𝑡 = 𝐹⃗ . 𝐷
(1)
Wint was computed with the equation of Nardello et al. [22] as follows: 𝑑
𝑊𝑖𝑛𝑡 = 𝑣 ∗ 𝑓 ∗ (1 + (1−𝑑)²) ∗ 0.08
(2)
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Where v is the walking speed (m s-1), f is the stride frequency, d is a duty factor based
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on step and stride times.
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In reference to Hof [7-8], the speed was expressed with a dimensionless
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parameter in m.s-1/√𝑔. 𝑙0 with 𝑙0 , the leg length and g, the acceleration gravity. Each
following:
𝑚𝑛𝑜𝑟𝑚 ∗𝑙𝑛𝑜𝑟𝑚 𝑚𝑖 ∗𝑙𝑖
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𝑊𝑛𝑜𝑟𝑚 = 𝑊𝑖 ∗
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work is in J kg-1 m-1 and each normalized work was computed according to the
(3)
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with 𝑊𝑖 being the external or internal work for each IS patient, 𝑚𝑛𝑜𝑟𝑚 the average mass of the healthy population, 𝑙𝑛𝑜𝑟𝑚 the average leg length of the healthy population, 𝑚𝑖 and 𝑙𝑖 the mass and leg length, respectively, of each IS patient. The thoracic-pelvic angle was obtained by subtracting the pelvis angle from the thorax angle [9]. The Range of Motion (difference between maximal and minimal angles, noted RoM) was computed for the thorax, thoracic-pelvis and pelvis during the complete gait cycle and stance phase in each plane using a Matlab-routine (version R2012, MathWorks Inc., Natick, MA, USA). Five strides per subject were analyzed [6]. The subjects walked along a 10 m-walkway at self-selected speed between two horizontal lines. 7
Journal Pre-proof 2.3 Statistical analysis Since all the biomechanical variables tended towards normal distribution (tested with Shapiro-Wilk test) and equality of variance, these variables are reported as mean (SD). The sample size relates to the statistical power (90%) computed for the range of frontal pelvic motion between patients with IS before and after spinal fusion. The following tests were used to establish the dependence of the gait data on the
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severity of the scoliosis: the Wilcoxon signed rank test for matched pairs (to compare data before and after spinal fusion), the Mann-Whitney test (to compare data computed
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for patients and controls). The significance level was set at p ≤ 0.05. Data analyses were
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performed using Statistica (version 13, Dell software, California, USA).
3.1 Demographics
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3. Results
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For the patients, the Cobb angle was reduced to 49.59° (SD 10.96) before fusion
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to 19.23° (SD 6.69) after fusion. According to the Lenke system [33], there were nine patients with type-1 Lenke curves, three patients with type-3 Lenke curves, two patients with type-4 Lenke curves, and eight patients with type-5 Lenke curves. Only three patients underwent spinal fusions using an anterior approach.
3.2 Gait speed, cadence and stride length Asymptomatic subjects walked faster than IS subjects (Table 2). IS patients also displayed a reduced cadence, which was associated with reduced stride length. One year after spinal fusion, gait speed, cadence and stride length were the same. No difference between populations was observed for normalized speed.
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Journal Pre-proof 3.3 Trunk displacements Table 3 presents thorax, thorax-pelvis and pelvis displacements for IS patients (before and one year after spinal fusion) and controls during a complete gait cycle and stance phase. Spinal fusion significantly increased pelvis mobility in the frontal plane. After spinal fusion, the thorax-pelvis segment increased its range of motion in the frontal plane during the stance phase but this fusion partially reduced
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thorax-pelvis mobility in the sagittal plane during the stance phase. Spinal fusion increased transverse thoracic RoM. Therefore, biomechanical stiffness was observed
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only on the thorax-pelvis segment in the sagittal plane during the stance phase.
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Differences can be observed between IS subjects and controls. Before spinal
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fusion, pelvis and thorax-pelvis segments showed significantly lower displacement in
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the frontal plane and sagittal plane than controls during the complete gait cycle and stance phase. After spinal fusion, IS reported lower significant displacements of the
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thorax in the transversal plane (during complete gait cycle only), lower significant displacements of the pelvis in each plane and lower significant displacements of the
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thorax-pelvis in the frontal and transversal planes.
3.4 External and internal work
Mechanical work is shown in table 4. Each work revealed no significant differences between the two groups of IS patients, both before spinal fusion and one year afterwards. Similarly, each group showed no significant difference with controls, both before and after spinal fusion. The normalized quantity for each work revealed that normalized external work for patients before and after surgery was greater than for controls. The normalized
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Journal Pre-proof internal work was not different between patients and controls. Spinal fusion had no effect on each type of work.
4. Discussion The purpose of this study was to determine the influence of spinal fusion for IS on the displacements of three parts of the trunk for each plane and on mechanical work in self-selected speed conditions. The results suggest that spinal fusion improves pelvic
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mobility in the frontal plane the self-selected speed condition. IS patients walked more
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slowly in this condition; the normalized quantity of Wext was higher for IS patients
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before and after spinal fusion. Regarding trunk mobility, the lower segments presented lower mobility during the stance phase than controls before spinal fusion. After fusion,
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whereas thorax-pelvis RoM was reduced in the sagittal plane, thoracic-pelvis RoM
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increased in the frontal plane during the stance phase.
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Previous studies considered several groups of scoliotic patients divided as a function of their Cobb angle [19,29]. These studies dealt with the relation between gait
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abnormalities (pelvis and lower limbs) and the severity of spinal deformity in patients with thoracic-lumbar IS, both under conditions of free speed [29] and imposed speed [19]. The results between these two studies differed despite considering the same type of scoliosis and recruiting patients with a similar age-range. Like these authors, our approach studied the RoM of the pelvis and considered this segment as essential. When comparing IS patients with asymptomatic subjects, we observed our hypothesized effect of back stiffness for thorax-pelvis segment in the sagittal plane and only during the stance phase. The thorax-pelvis segment was associated with lower RoM in the sagittal plane and greater displacements in the frontal plane. The pelvis displayed higher RoM in the frontal plane after fusion. Contrary to the lower back in the frontal plane, the thorax did not have a reduced range of motion in comparison to asymptomatic subjects. 10
Journal Pre-proof Like Holewijn et al. [9] and Schmid et al. [27], our analysis quantified thoracic, thoracolumbar and lumbar curves. Contrary to these authors, our asymptomatic population led us to evaluate normative data. Our results are in line with their research, and we were further able to operationalize stiffness effects during the stance phase. This stiffness effect was associated with the reorganization of the spine between the frontal and sagittal planes. The only difference between IS patients and controls was regarding the
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normalized quantity of Wext. The relation between gait speed and Wext was defined by
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a quadratic polynomial curve. This curve has a positive quadratic coefficient and shows
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a variation in Wext according the speed [2,31]. The same Wext may be obtained
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graphically from two different gait speeds. All these considerations can easily explain the lack of significant differences between IS subjects and controls. Our results are in
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line with those of a previous study [19], which compared Wint and Wext between IS
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and controls under imposed speed. Furthermore, we measured a lower standard deviation on each work in comparison to Mahaudens et al. [20]. Normalized work
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showed significant higher Wext before and after spinal fusion for IS patients. With such normalization, the effects of weight and length were accounted for. This result is in phase with the findings of Mahaudens et al. [19]. Restricted mobility was observed for the pelvis and thorax-pelvis in case of IS patients in comparison to controls. Therefore, scaling Wext may provide a specific tool necessary in the case of self-selected speed. We note three main limitations. Firstly, the CoM obtained from the Plug-in-Gait model was used to compute Wext. Recently, Pavei et al. [25] analyzed the dynamics of CoM computed from five inverse dynamics models (including Plug-in-Gait model) based on motion of body segments and one forward model based on ground reaction forces. The authors revealed that the model does not affect Wint. Moreover, as it
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Journal Pre-proof pertains to Wext, the Plug-in-Gait model induces the smallest difference with the data computed from ground reaction forces in comparison to the other model. The authors included only asymptomatic subject and these conclusions could be different in the case of an IS population. Secondly, depending on the authors and the forces studied, differences are not always measured between IS subjects and controls or between the left/right side for IS subjects [14,32-33]. Such forces are used to compute Wext [2]. Considering that self-
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selected speed is associated with a more stable gait condition with minimal variation on
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the motion of center of pressure (or CoP) and the motion of CoM [23], the IS patients
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included in this study may have compensated their trunk disorder and reduced the
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effects of ground forces and CoM. In this case, the motion of CoP relative to CoM (called CoP-CoM vector), namely variation in the CoP-CoM vector, could be
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condition [17].
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considered as another approach to analyze scoliosis gait under the self-selected speed
Thirdly, gait data were collected on a 10-m walkway, as was done in other
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studies [15,27]. This method led to discarding several entire walks and the need to control the variation of speed in the strides studied. Contrary to using a treadmill, walking on the ground does not need specific training [28].
5. Conclusions The current study provided insights into the kinematics of trunk and external/internal works in relation to free gait speed during gait in a condition of self-selected speed. The kinematics of the pelvis and thorax segments in IS patients revealed improvements after spinal fusion with a moderate change in the stiffening effect. This approach should lead to further research to evaluate levels fusion.
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Journal Pre-proof Conflict of interest statement None. Acknowledgements We thank P. Guillomet and K. Hodson for reviewing the English. We also thank R. Dumas and AL Hof for their advice.
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2015. Are the mediolateral joint forces in the lower limbs different between scoliotic and healthy subjects during gait? Scoliosis. 10 (Suppl. 2): S3. doi: 10.1186/1748-7161-10-S2S3.
[34] Zollinger M, Degache F, Currat G, Pochon L, Peyrot N, Newman CJ, Malatesta D. 2016. External Mechanical Work and Pendular Energy Transduction of Overground and Treadmill Walking in Adolescents with Unilateral Cerebral Palsy. Front Physiol. 13;7:121. doi: 10.3389/fphys.2016.00121.
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Journal Pre-proof Table 1. Baseline clinic demographic patient data, including age (in years) at date of gait analysis, sex (F: female; M: male), height, weight, Risser grade, Lenke curve type, primary Cobb angle (°), secondary Cobb angle (°), surgery approach (“Approach”), spinal fusion level. Cobb angles are expressed before (°) and after (°) spinal fusion. Table 2. Spatiotemporal parameters at preferred walking speed. Values are presented as mean (Sd). *: significant difference with controls (p ≤ 0.001);
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Table 3. Mobility of three parts of trunk: range of motion in degrees before/after spinal fusion during complete gait cycle and stance phase only for IS patients and controls.
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†: significant difference with controls; #: significant difference before/after spinal fusion.
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Table 4. External and internal works at preferred walking speed. Values are presented as mean (Sd).
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*: significant difference with controls (p ≤ 0.05)
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Table 1. Baseline clinic demographic patient data, including age (in years) at date of gait analysis, sex (F: female; M: male), height, weight, Risser grade, Lenke curve type, primary Cobb angle (°), secondary Cobb angle (°), surgery approach (“Approach”), spinal fusion level, group in relation of gait velocity. Cobb angles are expressed before (°) and after (°) spinal fusion. Ag Heig e ht (yr (m) )
1
17
2
17
3
15
4
17
5
25
6
17
1.63 5 1.70 5 1.53 8 1.60 0 1.74 5 1.63 5
Weig ht (kg)
Leg lengt h (m)
Gend er
Riss er
Lenk Cob e bC Clas Iaire s
55.0
0.88
F
5
1BN
52.0
0.90
F
4
1AN
40.5
0.81
F
3
1AN
49.0
0.88
F
4.5
5CN
23
Ant
52.0
0.97
F
5
5CN
50
Ant
50.0
0.88
F
4
5AN
50 55 45
60
Approa ch
Post Post Post
Post
Fusio n Level
T5L2 T5L2 T5L4 L1L4 L1L4 T5L3
Co bb C Iair e 29 14 19 13 20 20 16
10
14
11
17
12
15
13
21
14
16
15
16
16
15
17
20
18
17
19
14
20
19
21
17
22
16
4.5
5CN
55.0
0.91
F
4
5AN
61.0
0.87
M
5
5B-
50.5
0.81
F
4
4B-
48.0
0.84
M
5
1AN
55.5
0.84
F
4
3BN
57.0
0.84
F
5
5CN
46.0
0.81
F
4.5
1AN
51.0
0.79
F
4
48.0
0.88
F
4
58.0
0.88
M
43.0
0.83
F
48.0
0.80
39.0 45.0 76.0
3C-
1AN
5
4CN
5
3BN
F
4
1AN
0.76
F
5
1BN
0.83
F
4.5
1AN
M
4
5B-
1.07
60 50 74 44 50 50 35
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18
F
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9
0.93
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15
66.0
lP
8
1.67 0 1.67 5 1.78 5 1.56 5 1.59 5 1.57 0 1.64 0 1.54 0 1.50 0 1.60 0 1.72 5 1.54 0 1.59 0 1.50 0 1.60 0 1.78 0
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68 45 50 37 40 52 50 45 58
Post Post Post Post Post Post Ant Post Post Post Post Post Post Post Post Post
T5L4 T5L3 T4L2 T5L4 T5L2 T5L3 L1L4 T5L2 T5L4 T5L2 T4L4 T5L3 T5L2 T5L1 T5L2 T10L2
10 20 30 26 15 14 10 35 15 12 25 15 19 17 24 21
Table 2. Spatiotemporal parameters at preferred walking speed. Values are presented as mean (Sd) for IS before and after spinal fusion and controls.
Speed (m/s)
Normalized speed
Cadence (step/s)
Step length (m)
IS bef. fusion
1.07 (0.15) *
0.37 (0.05)
109.58 (8.9)*
0.59 (0.06) *
IS aft. fusion
1.04 (0.15) *
0.35 (0.05)
109.22 (8.65)*
0.57 (0.06) *
Controls
1.27 (0.13)
0.43 (0.04)
117.38 (7.59)
0.65 (0.06)
*: significant difference with controls (p ≤ 0.05) 17
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Table 3. Mobility of three parts of trunk: range of motion in degrees before/after spinal fusion during complete gait cycle and stance phase only for patients with IS and controls.
ThoraxPelvis
Sagittal Frontal
Sagittal
5.38 (2.74)
4.17 (1.61)
4.88 (1.75)
Stance Cycle Stance Cycle Stance
4.86 (2.75)# 7.18 (2.29)† 6.65 (1.66)#† 6.96 (2.04)† 6.61 (2.02)†
3.30 (1.33)# 8.09 (2.88)† 7.55 (2.41)#† 6.28 (2.38)† 5.98 (2.36)†
4.28 (1.71) 10.68 (2.09) 10.10 (2.09) 14.33 (4.43) 14.04 (4.42)
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Cycle
Controls 3.90 (1.27) 3.29 (1.26) 3.27 (1.01) 2.63 (0.67) 7.14 (2.82) 5.82 (1.98)
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Transversal
After spinal fusion 3.72 (0.86) 2.98 (0.82) 3.24 (1.73) 2.59 (1.05) 6.22 (1.75)†# 4.81 (1.17)
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Transversal
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Frontal
Cycle Stance Cycle Stance Cycle Stance
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Sagittal
Thorax
Before spinal fusion 3.82 (1.41) 3.22 (1.31) 3.14 (1.06) 2.61 (0.93) 5.67 (1.70)†# 4.36 (1.41)
2.98 (1.11) 2.89 (0.77)† 3.62 (0.93) 2.55 (0.99) 2.22 (0.65)† 3.18 (1.20) Frontal 5.89 (2.19)#† 6.99 (3.17)#† 9.59 (2.19) 5.72 (1.86)#† 6.66 (2.88)#† 8.83 (2.13) 8.61 (2.84)† 7.47 (2.53)† 11.89 (2.84) Transversal 7.70 (2.85)† 6.22 (2.37)† 11.00 (2.97) †: significant difference with controls; #: significant difference before/after spinal fusion.
Cycle Stance Cycle Stance Cycle Stance
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Pelvis
Table 4. External and internal works at preferred walking speed. Values are presented as mean (Sd). Wext (J kg-1 m-1)
Normalized Wext (J kg-1 m-1)
Wint (J kg-1 m-1)
Normalized Wint (J kg-1 m-1)
0.27 (0.05)
0.31 (0.09) *
0.23 (0.05)
0.26 (0.10)
IS aft. Surg.
0.29 (0.05)
0.36 (0.11)
*
0.24 (0.04)
0.29 (0.08)
Controls
0.25 (0.05)
0.26 (0.07)
0.27 (0.06)
0.27 (0.07)
IS bef. Surg.
*: significant difference with controls (p ≤ 0.05)
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Highlights Trunk mobility for idiopathic scoliosis patients
Mechanical works during gait
Influence of spinal fusion.
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Yannick Delpierre, Philippe Vernet, Annie Surdel PII:
S0268-0033(18)30990-2
DOI:
https://doi.org/10.1016/j.clinbiomech.2019.11.003
Reference:
JCLB 4895
To appear in:
Clinical Biomechanics
Received date:
27 November 2018
Accepted date:
8 November 2019
Please cite this article as: Y. Delpierre, P. Vernet and A. Surdel, Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis, Clinical Biomechanics (2019), https://doi.org/10.1016/j.clinbiomech.2019.11.003
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© 2019 Published by Elsevier.
Journal Pre-proof
Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis Yannick Delpierre(1), Philippe Vernet(1), Annie Surdel(1) (1) Laboratoire d’Analyse du Mouvement, Centre de l’Arche, Pole Régional du Handicap, 72650 St Saturnin – France; Corresponding author email: [email protected]
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Word count abstract: 248 words (/250). Total word count: 3000 (/3000)
Abstract
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Background: Scoliosis may have an effect on gait parameters, the kinematics of the
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lower limbs and the spine, and mechanical work with specific gait speed. Imposed gait
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speed may influence these effects. Following spinal fusion in the case of idiopathic scoliosis, patients fear subsequent and considerable back stiffness and kinetic
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consequences. The aim of this retrospective study was to evaluate the upper body range
conditions.
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of motion and mechanical work before and after spinal fusion in of free gait speed
Methods: Twenty-two patients with idiopathic scoliosis and twenty-two asymptomatic controls were included. Patients were analyzed before and one year after spinal fusion. Based on full body modeling and motion capture, we measured gait speed, cadence, stride length, the mobility of the upper and lower spinal segments (in each plane), and mechanical work (with and without dimensionless scaling strategy). Findings: Patients walked significantly slower than controls. The same speed was noticed before and after fusion. Only the lower back kinematics in the frontal plane was reduced before fusion. Spinal fusion further reduced the mobility of the pelvis segment
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Journal Pre-proof in the sagittal plane in comparison to controls. Scaling external work was associated with higher values for patients. Interpretation: Spinal fusion improves pelvic and thorax-pelvis mobility (during the stance phase) in the frontal plane. The impact of scoliosis on the upper body range of motion was limited on the thorax-pelvis, corresponding to a stiffening effect. With such restrictions, an increase in normalized external work was observed for similar normalized internal work.
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Keywords: scoliosis, gait analysis, spinal fusion, mechanical works, scaling quantity
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1. Introduction
Idiopathic Scoliosis (IS) is associated with three-dimensional deformity of the
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spine. This deformity has major repercussions related to cosmetic defect [11] and
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gait [1,4,6,9,14-15,18-20,26-27,29]. However, if brace treatment is ineffective in
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controlling the progression of scoliosis, spinal fusion may be an option to prevent further deterioration of the curve [18]. This surgery leads to back stiffness and reduces
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the spinal range of motion [9,15]. However, movements in the frontal pelvis (obliquity) and hips (abduction/adduction) are improved, in contrast to transversal shoulder motions (rotations) in the case of the thoracolumbar/lumbar primary structural curve, and are explained as stiffness in the counter-rotation between the two girdles, probably due to spine fusion [19]. The increase in hip and pelvic mobility in the frontal plane could be related to the need to compensate stiff girdle dissociation. The authors used kinematic data to describe this condition of stiffness under imposed constant gait speed. Here, stiffness represents an inability to move and walk as freely as healthy subjects. The long-term consequences of spinal fusion include frontal imbalance and a decrease of pelvic tilt in the sagittal plane under imposed gait speed [20].
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Journal Pre-proof The trunk and spine are not rigid segments but are made up of several segments. Arthrodesis can be considered by IS patients as a factor that increases spinal and trunk rigidities, reducing back mobility. This fear of lumbar stiffness or motion restrictions has an impact on activities of daily living [12]. Few studies have considered movements of the different segments that make up the trunk during gait [1,27]. Gait speed may impact the kinematic data of these different parts of the trunk [9,29], whereas spinal fusion does not modify self-selected speed [15].
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The first step in this analysis considers three principal segments of the back: thorax,
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thorax-pelvis and pelvis [9]. For each segment, the range of motion per plane allows
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quantifying the consequences of rigidity. It does not, however, give information on the
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efficiency of the locomotor mechanism. External work (Wext) corresponds to the mechanical work performed to move the Center of Mass (CoM). Internal work (Wint) is
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the work associated with the movements of each body segment. Mahaudens et al.
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presented demonstrated less mechanical work for IS patients with imposed speed (4 km h-1), but this speed could be considered as a biomechanical constraint in the case of
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spontaneously fast walkers [19]. Habitually, asymptomatic adolescents/young adults walked at a free gait speed around 1.17-1.6 m s-1 [4,13]. Minimizing the vertical motion of CoM in the case of gait speed reduction induces more metabolic energy consumption [24]. Thus, reducing walking speed could lead to an increase of Wext. Furthermore, in the case of patients with IS (before spinal fusion), several motion reductions have been observed on the lower limbs (like hip motion in the frontal and transversal planes), associated with reduced step length [14,27,29]. Joint motion restrictions on the lower limbs (in the case of adolescents with unilateral cerebral palsy) increase Wext [34]. Therefore, it seems possible to observe higher Wext in the case of patients with IS.
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Journal Pre-proof Finally, electrical activity was higher for all scoliosis groups [19]. Such results could be in phase with higher Wext or higher Wint. Wext and Wint vary as a function of gait speed. Therefore, is it preferable to impose speed (for instance with a treadmill, as described by Mahaudens et al. [19] or to apply free self-selected speed and compute the normalization of the work (based on the ratio between the anthropometric data of each patient and the asymptomatic population), as described by Hof [7,8]. The first solution assumes that the use of a treadmill has no
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effect on gait variables. The use of a treadmill to study the consequences of surgery may
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not be ideal for patients with poor individual balance performance and stability
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[3,10,30]. The second option requires the dimensionless scaling strategy [7,8].
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In the case of imposed-speed with a treadmill, the pelvis and structural spine changes are dependent. To our knowledge, no study has assessed the effect of surgery
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on pelvis mobility, spinal stiffness and the mechanical variables in self-selected speed
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condition and dimensionless scaling strategy. The aim of this study is to evaluate the incidence of scoliosis on gait in self-selected speed condition with regard to pelvis
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mobility (considering that pelvic motions in the frontal plane are sensitive to scoliosis and spinal fusion), and on the biomechanical stiffness of the trunk and mechanical work (with normalization), before and after spinal fusion. The hypotheses are:
1) Patients with IS improve their pelvic mobility in the frontal plane after spinal fusion in self-selected speed condition. 2) Biomechanical stiffness of the trunk (thorax and thorax-pelvis segments) distinguishes IS patients before spinal fusion from patients after spinal fusion. 3) Wext and Wint during gait are superior in IS patients (before spinal fusion) than in healthy population and spinal fusion tends to normality.
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Journal Pre-proof 2. Material and methodology 2.1 Subjects This
retrospective
study
was
approved
by
the
local
Ethical
Committee (no. 2017/08). All participants signed informed consent forms to use anonymous data. The study included a population consisting of twenty-two idiopathic scoliotic patients (before surgery: mean 16.9 years (Standard Deviation 3.1); height:
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mean 162.4 cm (SD 8.4); weight: mean 52.1 kg (SD 8.4 ); Cobb angle: mean 56.3° (SD 26.3); scoliosis oriented on right side; after surgery: mean 17.9 years (SD 3.1); height:
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mean 164 cm (SD 7.4); weight: mean 54.2 kg (SD 8.4); Cobb angle: mean 14.7° (SD
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14.6) and twenty-two control subjects (age: mean 18.5 years (SD 0.8); height: mean
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169.5 cm (SD 8.1); weight: mean 60.8 kg (SD 9.6 kg).
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The patients treated underwent surgery by the same orthopedic spine surgeon and were recruited among patients scheduled for spinal fusion between January 2008
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and December 2013. After surgery, all the patients followed an identical rehabilitation program. To avoid post-surgery discomfort and give patients time to restore their body
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image, movement analysis was performed two months preceding surgery and one year after spinal fusion. Analysis was included in the medical follow-up. Before surgery, standard bi-planar radiography was completed the same day as gait analysis. Cobbangles and Risser classification were determined for each patient based on radiographies.
Patients
were
excluded
if
they reported
mental
retardation,
musculoskeletal/neurological diseases, inequalities in leg length, locomotion injuries and previous surgical treatment of the spine. Healthy subjects were physical therapy students who did not suffer from musculoskeletal or neurological problems, scoliosis, inequalities in leg length, or obesity (>95th BMI per-age percentile).
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Journal Pre-proof 2.2 Data collection and data reduction Clinical gait analysis was performed using a motion capture system (VICON, Oxford Metrics, Oxford, UK, 100Hz) and 31 retro reflective spherical markers (14 mm) applied by a biomedical engineer with previous experience in this type of analysis. Both tools were used as part of the “Plug-in Gait Full Body” model. The software Nexus (version 1.8.5, Vicon, Oxford, UK) captured markers, defined gait events, and
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applied the model. These markers were placed directly on the skin at the following locations: bilateral shoulders (acromio-clavicular joint); bilateral elbows; bilateral
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wrists (radius-styloid process and ulna-styloid process); each hand (dorsum of the hand
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just below the medial head of metacarpal); the spinous process of the 7th cervical
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vertebra and 10th thoracic vertebra; bilateral anterior superior iliac spine (ASIS);
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sacrum (SACR), considered as the middle of the segment between posterior superior iliac spines; lateral tibial plateau; lateral malleoli; second metatarsal head; heel; lateral
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epicondyle of the femur; bilateral tibial wands; left and right femoral wands [5]. Therefore, the thorax was defined by the markers on C7, T10, sternum and clavicle
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(jugular notch). The pelvis was defined using markers on the two ASIS and SACR. Spatiotemporal gait data included gait speed, cadence and stride length. As proposed in [7], a normalized and non-dimensionless gait speed was computed. Two AMTI (MCA model) synchronized force platforms (1000 Hz) were located in the middle of the walking corridor. No specific instructions were given to subjects in relation to correctly placing their feet on each force platform to avoid perturbation on gait. Wext and Wint were computed and recorded in J kg-1 m-1 [2,22,31]. Wext corresponds to the dot product of the Ground Reaction Force and displacement of the CoM vectors as developed by Cavagna [2] and applied by Willems et al. [31]. Based on
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Journal Pre-proof F (the result of the external forces applied to the body), D (the displacement of CoM), Wext is given by: ⃗⃗ 𝑊𝑒𝑥𝑡 = 𝐹⃗ . 𝐷
(1)
Wint was computed with the equation of Nardello et al. [22] as follows: 𝑑
𝑊𝑖𝑛𝑡 = 𝑣 ∗ 𝑓 ∗ (1 + (1−𝑑)²) ∗ 0.08
(2)
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Where v is the walking speed (m s-1), f is the stride frequency, d is a duty factor based
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on step and stride times.
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In reference to Hof [7-8], the speed was expressed with a dimensionless
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parameter in m.s-1/√𝑔. 𝑙0 with 𝑙0 , the leg length and g, the acceleration gravity. Each
following:
𝑚𝑛𝑜𝑟𝑚 ∗𝑙𝑛𝑜𝑟𝑚 𝑚𝑖 ∗𝑙𝑖
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𝑊𝑛𝑜𝑟𝑚 = 𝑊𝑖 ∗
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work is in J kg-1 m-1 and each normalized work was computed according to the
(3)
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with 𝑊𝑖 being the external or internal work for each IS patient, 𝑚𝑛𝑜𝑟𝑚 the average mass of the healthy population, 𝑙𝑛𝑜𝑟𝑚 the average leg length of the healthy population, 𝑚𝑖 and 𝑙𝑖 the mass and leg length, respectively, of each IS patient. The thoracic-pelvic angle was obtained by subtracting the pelvis angle from the thorax angle [9]. The Range of Motion (difference between maximal and minimal angles, noted RoM) was computed for the thorax, thoracic-pelvis and pelvis during the complete gait cycle and stance phase in each plane using a Matlab-routine (version R2012, MathWorks Inc., Natick, MA, USA). Five strides per subject were analyzed [6]. The subjects walked along a 10 m-walkway at self-selected speed between two horizontal lines. 7
Journal Pre-proof 2.3 Statistical analysis Since all the biomechanical variables tended towards normal distribution (tested with Shapiro-Wilk test) and equality of variance, these variables are reported as mean (SD). The sample size relates to the statistical power (90%) computed for the range of frontal pelvic motion between patients with IS before and after spinal fusion. The following tests were used to establish the dependence of the gait data on the
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severity of the scoliosis: the Wilcoxon signed rank test for matched pairs (to compare data before and after spinal fusion), the Mann-Whitney test (to compare data computed
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for patients and controls). The significance level was set at p ≤ 0.05. Data analyses were
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performed using Statistica (version 13, Dell software, California, USA).
3.1 Demographics
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3. Results
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For the patients, the Cobb angle was reduced to 49.59° (SD 10.96) before fusion
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to 19.23° (SD 6.69) after fusion. According to the Lenke system [33], there were nine patients with type-1 Lenke curves, three patients with type-3 Lenke curves, two patients with type-4 Lenke curves, and eight patients with type-5 Lenke curves. Only three patients underwent spinal fusions using an anterior approach.
3.2 Gait speed, cadence and stride length Asymptomatic subjects walked faster than IS subjects (Table 2). IS patients also displayed a reduced cadence, which was associated with reduced stride length. One year after spinal fusion, gait speed, cadence and stride length were the same. No difference between populations was observed for normalized speed.
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Journal Pre-proof 3.3 Trunk displacements Table 3 presents thorax, thorax-pelvis and pelvis displacements for IS patients (before and one year after spinal fusion) and controls during a complete gait cycle and stance phase. Spinal fusion significantly increased pelvis mobility in the frontal plane. After spinal fusion, the thorax-pelvis segment increased its range of motion in the frontal plane during the stance phase but this fusion partially reduced
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thorax-pelvis mobility in the sagittal plane during the stance phase. Spinal fusion increased transverse thoracic RoM. Therefore, biomechanical stiffness was observed
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only on the thorax-pelvis segment in the sagittal plane during the stance phase.
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Differences can be observed between IS subjects and controls. Before spinal
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fusion, pelvis and thorax-pelvis segments showed significantly lower displacement in
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the frontal plane and sagittal plane than controls during the complete gait cycle and stance phase. After spinal fusion, IS reported lower significant displacements of the
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thorax in the transversal plane (during complete gait cycle only), lower significant displacements of the pelvis in each plane and lower significant displacements of the
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thorax-pelvis in the frontal and transversal planes.
3.4 External and internal work
Mechanical work is shown in table 4. Each work revealed no significant differences between the two groups of IS patients, both before spinal fusion and one year afterwards. Similarly, each group showed no significant difference with controls, both before and after spinal fusion. The normalized quantity for each work revealed that normalized external work for patients before and after surgery was greater than for controls. The normalized
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Journal Pre-proof internal work was not different between patients and controls. Spinal fusion had no effect on each type of work.
4. Discussion The purpose of this study was to determine the influence of spinal fusion for IS on the displacements of three parts of the trunk for each plane and on mechanical work in self-selected speed conditions. The results suggest that spinal fusion improves pelvic
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mobility in the frontal plane the self-selected speed condition. IS patients walked more
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slowly in this condition; the normalized quantity of Wext was higher for IS patients
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before and after spinal fusion. Regarding trunk mobility, the lower segments presented lower mobility during the stance phase than controls before spinal fusion. After fusion,
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whereas thorax-pelvis RoM was reduced in the sagittal plane, thoracic-pelvis RoM
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increased in the frontal plane during the stance phase.
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Previous studies considered several groups of scoliotic patients divided as a function of their Cobb angle [19,29]. These studies dealt with the relation between gait
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abnormalities (pelvis and lower limbs) and the severity of spinal deformity in patients with thoracic-lumbar IS, both under conditions of free speed [29] and imposed speed [19]. The results between these two studies differed despite considering the same type of scoliosis and recruiting patients with a similar age-range. Like these authors, our approach studied the RoM of the pelvis and considered this segment as essential. When comparing IS patients with asymptomatic subjects, we observed our hypothesized effect of back stiffness for thorax-pelvis segment in the sagittal plane and only during the stance phase. The thorax-pelvis segment was associated with lower RoM in the sagittal plane and greater displacements in the frontal plane. The pelvis displayed higher RoM in the frontal plane after fusion. Contrary to the lower back in the frontal plane, the thorax did not have a reduced range of motion in comparison to asymptomatic subjects. 10
Journal Pre-proof Like Holewijn et al. [9] and Schmid et al. [27], our analysis quantified thoracic, thoracolumbar and lumbar curves. Contrary to these authors, our asymptomatic population led us to evaluate normative data. Our results are in line with their research, and we were further able to operationalize stiffness effects during the stance phase. This stiffness effect was associated with the reorganization of the spine between the frontal and sagittal planes. The only difference between IS patients and controls was regarding the
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normalized quantity of Wext. The relation between gait speed and Wext was defined by
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a quadratic polynomial curve. This curve has a positive quadratic coefficient and shows
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a variation in Wext according the speed [2,31]. The same Wext may be obtained
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graphically from two different gait speeds. All these considerations can easily explain the lack of significant differences between IS subjects and controls. Our results are in
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line with those of a previous study [19], which compared Wint and Wext between IS
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and controls under imposed speed. Furthermore, we measured a lower standard deviation on each work in comparison to Mahaudens et al. [20]. Normalized work
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showed significant higher Wext before and after spinal fusion for IS patients. With such normalization, the effects of weight and length were accounted for. This result is in phase with the findings of Mahaudens et al. [19]. Restricted mobility was observed for the pelvis and thorax-pelvis in case of IS patients in comparison to controls. Therefore, scaling Wext may provide a specific tool necessary in the case of self-selected speed. We note three main limitations. Firstly, the CoM obtained from the Plug-in-Gait model was used to compute Wext. Recently, Pavei et al. [25] analyzed the dynamics of CoM computed from five inverse dynamics models (including Plug-in-Gait model) based on motion of body segments and one forward model based on ground reaction forces. The authors revealed that the model does not affect Wint. Moreover, as it
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Journal Pre-proof pertains to Wext, the Plug-in-Gait model induces the smallest difference with the data computed from ground reaction forces in comparison to the other model. The authors included only asymptomatic subject and these conclusions could be different in the case of an IS population. Secondly, depending on the authors and the forces studied, differences are not always measured between IS subjects and controls or between the left/right side for IS subjects [14,32-33]. Such forces are used to compute Wext [2]. Considering that self-
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selected speed is associated with a more stable gait condition with minimal variation on
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the motion of center of pressure (or CoP) and the motion of CoM [23], the IS patients
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included in this study may have compensated their trunk disorder and reduced the
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effects of ground forces and CoM. In this case, the motion of CoP relative to CoM (called CoP-CoM vector), namely variation in the CoP-CoM vector, could be
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condition [17].
lP
considered as another approach to analyze scoliosis gait under the self-selected speed
Thirdly, gait data were collected on a 10-m walkway, as was done in other
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studies [15,27]. This method led to discarding several entire walks and the need to control the variation of speed in the strides studied. Contrary to using a treadmill, walking on the ground does not need specific training [28].
5. Conclusions The current study provided insights into the kinematics of trunk and external/internal works in relation to free gait speed during gait in a condition of self-selected speed. The kinematics of the pelvis and thorax segments in IS patients revealed improvements after spinal fusion with a moderate change in the stiffening effect. This approach should lead to further research to evaluate levels fusion.
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Journal Pre-proof Conflict of interest statement None. Acknowledgements We thank P. Guillomet and K. Hodson for reviewing the English. We also thank R. Dumas and AL Hof for their advice.
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Journal Pre-proof Table 1. Baseline clinic demographic patient data, including age (in years) at date of gait analysis, sex (F: female; M: male), height, weight, Risser grade, Lenke curve type, primary Cobb angle (°), secondary Cobb angle (°), surgery approach (“Approach”), spinal fusion level. Cobb angles are expressed before (°) and after (°) spinal fusion. Table 2. Spatiotemporal parameters at preferred walking speed. Values are presented as mean (Sd). *: significant difference with controls (p ≤ 0.001);
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Table 3. Mobility of three parts of trunk: range of motion in degrees before/after spinal fusion during complete gait cycle and stance phase only for IS patients and controls.
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†: significant difference with controls; #: significant difference before/after spinal fusion.
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Table 4. External and internal works at preferred walking speed. Values are presented as mean (Sd).
lP
*: significant difference with controls (p ≤ 0.05)
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Table 1. Baseline clinic demographic patient data, including age (in years) at date of gait analysis, sex (F: female; M: male), height, weight, Risser grade, Lenke curve type, primary Cobb angle (°), secondary Cobb angle (°), surgery approach (“Approach”), spinal fusion level, group in relation of gait velocity. Cobb angles are expressed before (°) and after (°) spinal fusion. Ag Heig e ht (yr (m) )
1
17
2
17
3
15
4
17
5
25
6
17
1.63 5 1.70 5 1.53 8 1.60 0 1.74 5 1.63 5
Weig ht (kg)
Leg lengt h (m)
Gend er
Riss er
Lenk Cob e bC Clas Iaire s
55.0
0.88
F
5
1BN
52.0
0.90
F
4
1AN
40.5
0.81
F
3
1AN
49.0
0.88
F
4.5
5CN
23
Ant
52.0
0.97
F
5
5CN
50
Ant
50.0
0.88
F
4
5AN
50 55 45
60
Approa ch
Post Post Post
Post
Fusio n Level
T5L2 T5L2 T5L4 L1L4 L1L4 T5L3
Co bb C Iair e 29 14 19 13 20 20 16
10
14
11
17
12
15
13
21
14
16
15
16
16
15
17
20
18
17
19
14
20
19
21
17
22
16
4.5
5CN
55.0
0.91
F
4
5AN
61.0
0.87
M
5
5B-
50.5
0.81
F
4
4B-
48.0
0.84
M
5
1AN
55.5
0.84
F
4
3BN
57.0
0.84
F
5
5CN
46.0
0.81
F
4.5
1AN
51.0
0.79
F
4
48.0
0.88
F
4
58.0
0.88
M
43.0
0.83
F
48.0
0.80
39.0 45.0 76.0
3C-
1AN
5
4CN
5
3BN
F
4
1AN
0.76
F
5
1BN
0.83
F
4.5
1AN
M
4
5B-
1.07
60 50 74 44 50 50 35
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F
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9
0.93
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15
66.0
lP
8
1.67 0 1.67 5 1.78 5 1.56 5 1.59 5 1.57 0 1.64 0 1.54 0 1.50 0 1.60 0 1.72 5 1.54 0 1.59 0 1.50 0 1.60 0 1.78 0
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68 45 50 37 40 52 50 45 58
Post Post Post Post Post Post Ant Post Post Post Post Post Post Post Post Post
T5L4 T5L3 T4L2 T5L4 T5L2 T5L3 L1L4 T5L2 T5L4 T5L2 T4L4 T5L3 T5L2 T5L1 T5L2 T10L2
10 20 30 26 15 14 10 35 15 12 25 15 19 17 24 21
Table 2. Spatiotemporal parameters at preferred walking speed. Values are presented as mean (Sd) for IS before and after spinal fusion and controls.
Speed (m/s)
Normalized speed
Cadence (step/s)
Step length (m)
IS bef. fusion
1.07 (0.15) *
0.37 (0.05)
109.58 (8.9)*
0.59 (0.06) *
IS aft. fusion
1.04 (0.15) *
0.35 (0.05)
109.22 (8.65)*
0.57 (0.06) *
Controls
1.27 (0.13)
0.43 (0.04)
117.38 (7.59)
0.65 (0.06)
*: significant difference with controls (p ≤ 0.05) 17
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Table 3. Mobility of three parts of trunk: range of motion in degrees before/after spinal fusion during complete gait cycle and stance phase only for patients with IS and controls.
ThoraxPelvis
Sagittal Frontal
Sagittal
5.38 (2.74)
4.17 (1.61)
4.88 (1.75)
Stance Cycle Stance Cycle Stance
4.86 (2.75)# 7.18 (2.29)† 6.65 (1.66)#† 6.96 (2.04)† 6.61 (2.02)†
3.30 (1.33)# 8.09 (2.88)† 7.55 (2.41)#† 6.28 (2.38)† 5.98 (2.36)†
4.28 (1.71) 10.68 (2.09) 10.10 (2.09) 14.33 (4.43) 14.04 (4.42)
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Cycle
Controls 3.90 (1.27) 3.29 (1.26) 3.27 (1.01) 2.63 (0.67) 7.14 (2.82) 5.82 (1.98)
lP
Transversal
After spinal fusion 3.72 (0.86) 2.98 (0.82) 3.24 (1.73) 2.59 (1.05) 6.22 (1.75)†# 4.81 (1.17)
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Transversal
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Frontal
Cycle Stance Cycle Stance Cycle Stance
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Sagittal
Thorax
Before spinal fusion 3.82 (1.41) 3.22 (1.31) 3.14 (1.06) 2.61 (0.93) 5.67 (1.70)†# 4.36 (1.41)
2.98 (1.11) 2.89 (0.77)† 3.62 (0.93) 2.55 (0.99) 2.22 (0.65)† 3.18 (1.20) Frontal 5.89 (2.19)#† 6.99 (3.17)#† 9.59 (2.19) 5.72 (1.86)#† 6.66 (2.88)#† 8.83 (2.13) 8.61 (2.84)† 7.47 (2.53)† 11.89 (2.84) Transversal 7.70 (2.85)† 6.22 (2.37)† 11.00 (2.97) †: significant difference with controls; #: significant difference before/after spinal fusion.
Cycle Stance Cycle Stance Cycle Stance
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Pelvis
Table 4. External and internal works at preferred walking speed. Values are presented as mean (Sd). Wext (J kg-1 m-1)
Normalized Wext (J kg-1 m-1)
Wint (J kg-1 m-1)
Normalized Wint (J kg-1 m-1)
0.27 (0.05)
0.31 (0.09) *
0.23 (0.05)
0.26 (0.10)
IS aft. Surg.
0.29 (0.05)
0.36 (0.11)
*
0.24 (0.04)
0.29 (0.08)
Controls
0.25 (0.05)
0.26 (0.07)
0.27 (0.06)
0.27 (0.07)
IS bef. Surg.
*: significant difference with controls (p ≤ 0.05)
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Highlights Trunk mobility for idiopathic scoliosis patients
Mechanical works during gait
Influence of spinal fusion.
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