Effects of dynamic balance on adolescent idiopathic scoliosis : motor response analysis - Assessed with the Equitest®

Details

Supervisors

Mahaudens, Philippe ; Charon, Hélène

Faculty

Faculté des sciences de la motricité

Degree label

Master [120] en sciences de la motricité, orientation générale, à finalité spécialisée: kinésithérapie musculo-squelettique

Abstract

Objective: The aim of this study was to evaluate the motor responses during dynamic balance control of adolescents with idiopathic scoliosis, compared to healthy adolescents, using the Motor Control Test (MCT) with the Equitest® system. Background: Adolescent idiopathic scoliosis (AIS) is the most prevalent form of scoliosis. AIS patients would present disturbances in balance control, involving impaired multisensory integration of vestibular, visual, and somatosensory inputs. Therefore, biomechanical aspects and sensorimotor issues contribute to a reorganization of static and dynamic balance control. No studies have looked at motor strategies in both legs in different scoliotic groups compared with a control group. Materials and methods: 54 scoliotic patients and 54 control subjects participated in this study. The AIS patients were divided into three groups according to the Cobb angle curve: Cobb≤20° (n=14), 20°<Cobb<40° (n=34), Cobb ≥40° (n=6) and into three groups according to the location of the major curve: major thoracic (n=33), major lumbar (n=16), double major (n=5). This enabled the comparison of AIS patients with healthy adolescents, according to the severity of the scoliosis and according to the location of the scoliosis. A Computerized dynamic posturography, the Equitest®, was used to record postural responses in terms of weight symmetry, latency, and strength response. Therefore, only the Motor Control Test (MCT) was analyzed in this study including several perturbations, 3 backward translations and 3 forward translations with different magnitudes (small, medium, and large). Results: Weight symmetry on the legs showed no significant difference between any groups or subgroups. Any significant difference was observed in the symmetry of the leg response latency between the different groups and in the comparison for left limb’s latency and right limb’s latency. There was no significant difference in strength symmetry analysis between the different groups. In the analysis of the strength of the right and left limb, AIS subjects of the group 20°<Cobb<40° was greater than in control groups. In this same analysis between AIS major thoracic, AIS major lumbar and control subjects, there are significant differences with control group in all conditions except for small translation backward. Discussion: This study has some limits including the size of the samples, the homogeneity of the demographic data and there are no standard data for the MCT analysis of Equitest® for adolescents. Weight distribution is symmetrical, which could be explained by compensation in the central nervous system. As for the strength symmetry of the motor responses, back muscles could be compensated for by the muscular chain of the lower limbs. The greater force exerted by the right and left leg is consistent with previous studies showing greater muscle activity in scoliotic subjects. The central nervous system and vestibular afferent system appear to have an impact in motor responses.