Accepted Manuscript Title: Gait in patients with Adolescent Idiopathic Scoliosis. Effect of surgery at 10 years of follow-up Authors: Philippe Mahaudens, France Dalemans, Xavier Banse, Maryline Mousny, Olivier Cartiaux, Christine Detrembleur PII: DOI: Reference:
S0966-6362(18)30007-9 https://doi.org/10.1016/j.gaitpost.2018.01.007 GAIPOS 5921
To appear in:
Gait & Posture
Received date: Revised date: Accepted date:
24-5-2017 22-11-2017 11-1-2018
Please cite this article as: Mahaudens Philippe, Dalemans France, Banse Xavier, Mousny Maryline, Cartiaux Olivier, Detrembleur Christine.Gait in patients with Adolescent Idiopathic Scoliosis.Effect of surgery at 10 years of follow-up.Gait and Posture https://doi.org/10.1016/j.gaitpost.2018.01.007 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.
Title Gait in patients with Adolescent Idiopathic Scoliosis. Effect of surgery at 10 years of followup.
AUTHORS
Cliniques Universitaires St Luc, Service d’orthopédie et de traumatologie de l’appareil
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Philippe Mahaudens, PhDa,b,c*, France Dalemans, MDa, Xavier Banse, MD, PhDa,b , Maryline Mousny, MD, PhDa,b , Olivier Cartiaux, PhDb, Christine Detrembleur, PhDb
locomoteur, Avenue Hippocrate 10, B-1200 Brussels, Belgium
Université Catholique de Louvain, Secteur des Sciences de la Santé, Institut de Recherche
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Expérimental et Clinique, Neuro Musculo Skeletal Lab (NMSK), Avenue Mounier 53, B-1200
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Brussels, Belgium
Cliniques Universitaires St Luc, Service de médecine physique et réadaptation, Avenue
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Hippocrate 10, B-1200 Brussels, Belgium
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* Corresponding author : Université Catholique de Louvain, Secteur des Sciences de la Santé, Institut de Recherche Expérimental et Clinique, Neuro Musculo Skeletal Lab (NMSK), Avenue Mounier 53, B-1200 Brussels, Belgium. Tél : +3227645365 E-mail address :
[email protected]
Research highlights
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Back muscles EMG is increased in adolescent idiopathic scoliosis during gait Mechanichal and metabolic energy are altered in AIS whatever the curve severity Spinal arthrodesis in AIS reduces spine motion without to alter the gait kinematics At long term after surgery, back muscles EMG, during gait, tends to the norms Metabolic energy remains excessive in AIS despite the long term surgical follow-up
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Abstract PURPOSE: To assess radiological and gait biomechanical changes before, at one and 10 years after surgery in AIS patients.
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METHODS: This clinical prospective study included fifteen adult women (mean[SD] age:
26[1] years) diagnosed with thoraco-lumbar/ lumbar AIS and operated 10 years ago. Clinical,
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radiological and gait variables, including kinematics, electromyography (EMG), mechanics
and energetics were compared between presurgery (S0), 1 year (S1) and 10 years (S2)
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postsurgery period using a one way repeated measure ANOVA.
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RESULTS: The Cobb angle of the scoliosis curve was reduced by 55% at 1 year postsugery but
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only by 37% at 10 years postsurgery suggesting a loss of 32% over time. Frontal plumb line
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C7-S1 distance was significantly improved by surgery (- 44%) and remained stable at 10 years
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postsurgery. Lower limb kinematics was not affected by the surgery at long term. Excessive bilateral activation of lombo-pelvic muscles, observed before surgery, decreased significantly
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at S1 and S2 period. Mechanical energy increased significantly between S0, S1 and S2
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session, without any change for the energetic variables. CONCLUSIONS: Between 1 and 10 years post-surgery, thoraco-lumbar/lumbar AIS women showed a few decompensation of the curve without any change of the improved frontal
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body balance. Lower limbs and pelvic motion, during gait, was not affected by the surgery. But presurgical excessive EMG activity of the lumbo-pelvic muscle and reduced mechanical energy produced to walk get similar normal patterns. Only the oxygen consumption remained excessive probably due to physical deconditioning or postural instability.
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Keywords
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AIS – Surgery - follow-up – Cobb angle – gait – EMG - Energetics
Introduction
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Adolescent idiopathic scoliosis (AIS) accounts for approximately 70% of all scoliosis cases [1].
Although most scoliosis curves will need no intervention [2], almost 10% of the AIS patients underwent a curve progression above 40-50° before the end of the growth. For these
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patients, surgery remains the ultimate way to correct and stabilize the deformity, allowing
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both preserving the body equilibrium and maintaining as many mobile spinal segments as
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possible [3]. Although, the surgical arthrodesis reduces partly the mobility of the spine [4],
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the functional activities such as walking is globally improved at short-term follow-up (one
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year). Spatio-temporal parameters (walking speed, step length and cadence) are improved [5] without any deterioration of lower limbs displacement [5, 6]. Mechanical muscular work
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is also improved. Electromyographic activity of the paraspinal muscles is more symmetric [7]
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but remains prolonged as compared to healthy subjects [5]. The energy consumption continues to be excessive [5], probably due to the important co-contraction of the lumbopelvic muscles. However at long-term follow-up, decompensations of the lower part of the
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spine under the arthrodesis , progression of a lumbar scoliosis curve [8], increase of L4 obliquity to the pelvis [9] and accelerated rate of L5-S1 disc degeneration [10] have been documented. This spinal decompensation is associated to greater pelvic axial rotation observed radiographically [11]. Such pelvic asymmetries are correlated to the severity of the curve [12] inducing gait motion abnormalities [13] and postural asymmetry [14] in non3
operated AIS patients. Increased EMG activity of the paraspinal muscle [15] has been also observed in case of severe curves and postural asymmetry. This could alter the metabolic energy expenditure during gait. To our knowledge, no study has assessed the evolution of gait biomechanics between pre, post 1 year and post 10 years surgery AIS patients with thoraco-lumbar/lumbar curves.
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The goal of this study was to compare gait biomechanics and Cobb angle after 10 years of
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surgical follow-up in a sample of thoraco-lumbar/lumbar AIS before, at 1 year and 10 years postsurgery. The hypothesis was that for long-term postsurgical patients, spinal decompensation could happen and would elicit alteration of gait biomechanics by reducing
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pelvis angular displacement, increasing paraspinal EMG activity with as consequence an
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increase of energy cost of walking.
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Material and method
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Study population
Our prospective study included 15 AIS girls before surgery, at 1 and 10 years after surgery.
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The mean age at 10 years follow-up was 26±1 years. All patients had a
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thoracolumbar/lumbar primary structural curve according to Lenke’s classification [16]. They were all first treated conservatively by brace at adolescence and underwent surgery at 15±1
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years old.
No patient had complication such as hardware failure, revision surgeries, graft rejection, infection. The patients have been operated by the same two orthopaedic surgeons. Six of them had undergone an anterior spinal fusion and nine of them a posterior spinal fusion according to clinical prerequisites [5]. 4
Each subject had freely signed and participated in the study, approved by the local ethics committee (N° B403201317994). The patients were submitted to a clinical and radiological examination and tridimensional (3D) instrumented gait analysis.
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Clinical and radiological examination Clinical examination included body weight, height and body mass index (BMI). Then, all
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patients have been assessed by antero-posterior (AP) full spine radiography. Cobb angle
curve [17] and frontal body balance (assessed by the frontal plumb line C7–S1 distance) [6]
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were measured respectively as illustrated in the Figure 1.
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3D instrumented gait analysis
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Gait was assessed by 3D analysis, including synchronous kinematic, electromyographic
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(EMG) of quadratus lumborum (QL), erector spinae (ES), rectus femoris (RF), semitendinosus
measurements (Fig.2).
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(ST), tibialis anterior (TA) and gastrocnemius (G) muscles, mechanical and energetic
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Segmental kinematics were measured with eight infrared cameras at 200 Hz (Elite system,
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BTS, Italy) allowing computation of the 3D angular displacement of pelvis segment and hip, knee and ankle joints [18]. The bilateral EMG activity of aforementioned muscles (Figure 2) was recorded by a
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telemetry EMG system (Telemg, BTS, Italy) with surface electrodes (Medi-Trace, Graphic Controls Corporation, NY, USA). The signal was digitised at 1000 Hz, full-wave rectified, and filtered (bandwidth 25-300Hz). The onset and cessation of muscle activity were determined as described by Van Boxtel et al. [19].
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Kinematic and EMG data were normalised to 100% of the time of the stride, 0% corresponding to the initial contact of the left foot. The total mechanical work (Wtot), i.e the sum of the positive increments calculated to kinetic and potential energy curves linked to the work performed by the body muscles to go
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forward, was divided into the external work (Wext) performed to move the centre of body mass (COMb) relative to the surroundings and the internal work (Wint) performed to move
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the body segments relative to the COMb [20].
Wext was computed from strain gauges (located under the 4 corners of the treadmill) that measured and computed at 200Hz the 3D ground reaction forces according to Cavagna [21].
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Wint was computed from kinematic data [20].
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The metabolic cost of walking was determined by the subject’s oxygen consumption ( V O2 )
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and carbon dioxide production ( V CO2) measured throughout the treadmill test with an ergospirometer (Quark b2, Cosmed, Italy).
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The mass-specific gross energy consumption rate (W kg–1) was obtained from the oxygen
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consumption rate using an energy equivalent of oxygen, taking into account the measured respiratory exchange ratio (RER) [22] .
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The RER, computed as the ratio between V CO2 and V O2, remained always between 0.65 and 1 to prevent anaerobic effort (>1) or an escape of air by the mask (
