Adolescent Idiopathic Scoliosis : effect of curve’s severity and surgery on 3D body center of mass’s displacements during gait

Details

Supervisors

Mahaudens, Philippe ; Detrembleur, Christine

Faculty

Faculté des sciences de la motricité

Degree label

Master [120] en sciences de la motricité, orientation générale

Abstract

Background : controversial results were reported regarding to some biomechanical gait parameters such as kinematic, kinetic and spatiotemporal parameters in adolescent idiopathic scoliosis (AIS). But, consistent results showed an excessive electrical activation of paravertebral muscles with an abnormal mediolateral displacement of the center of pressure during gait. More, the mechanical energy provided by the muscles of the body to move it was altered. The assessment of the tridimensional (3D) body center of mass (COM) displacement could bring more insight to this alteration. Objectives : this study aimed firstly to compare 3D COM displacement and spatiotemporal parameters between control and scoliosis adolescent groups during gait at comfortable speed, secondly to observe the effect of the scoliosis curves’ severity on COM and spatiotemporal parameters, and thirdly to assess the influence of the surgery on these parameters at short and long terms. Method : 3D COM and spatiotemporal parameters were assessed in thirteen healthy girls and 45 AIS patients (mild, moderate and severe stage of spinal deformity) whom 21 AIS required spinal surgery. The surgical group was evaluated at presurgery (21 patients), 1 year postsurgery (21 patients) and 7 years postsurgery (14 patients) periods. Normal and scoliotic gait were assessed using a three-dimensional motion analysis system, including synchronous kinematic and ground reaction forces measurements. Results : comparison between AIS and normal gait showed significant differences regarding to cadence (p=0,002), step length (p<0,001), stance phase (p<0,001), and COM lateral (p<0,001) and forward (p<0,001) displacements. These discrepancies were demonstrated unrelated to scoliosis curve’s side. In AIS gait, the stance phase decreased independently to scoliosis curves’ severity (2,3 - 2,6%). The COM lateral displacement was reduced from mild stage of AIS, with a tendency to aggravation in moderate stage of disease and a return to the norm in severe stage of spinal condition. Strong correlations were demonstrated between cadence and step length (r= -0,864 ; p<0,001), cadence and COM forward displacement (r= -0,887 ; p<0,001), and, step length and COM forward displacement (r=0,872 ; p<0,001). These three parameters followed a common progress related to spinal deformity worsening. The discrepancy from normal gait started at moderate stage of AIS, with a return to the norm at severe stage of the disease. More, spine surgery allowed a significant improvement of step length and a tendency to stance phase enhancement. Decreases of COM total forward and lateral displacements occurred only in 7 years postsurgery group. Conclusions : discrepancies were reported between control and scoliosis adolescent groups during gait, regarding both COM displacements (lateral and forward) and spatiotemporal parameters (cadence, step length and stance phase). Among these changes, only the stance phase was unrelated to scoliosis curves’ severity. The others parameters appeared to evolve during the aggravation of spinal deformity, according to a gradual maturation of Central Nervous System (CNS). The spine surgery, allowing a slight improvement of spatiotemporal parameters and no effect on COM displacements, confirmed mild involvement of biomechanical factors on AIS gait.