General Session: Pediatric Spine
Presented by: J.J. Varghese - View Audio/Video Presentation (Members Only)
V. Lafage(1), J.J. Varghese(1,2), A. Patel(1,2), D. Leven(2), L. Day(2), E. Godwin(2), C. Paulino(2)
(1) Hospital for Special Surgery, New York, NY, United States
(2) State University of New York, Downstate Medical Center, Brooklyn, NY, United States
Introduction: Adolescent Idiopathic Scoliosis (AIS) results in structural/compensatory curves in the coronal plane, flattened curves in the sagittal plane, and marked vertebral rotation in the axial plane. The axial plane deformity and its effect on function are not well understood. The purpose of this investigation was to evaluate the relationship between radiographic measures for AIS and axial plane gait analysis.
Methods: Seventy-two AIS patients, mean 13.7 years and mean Cobb angle 58.1°, were prospectively enrolled into this gait analysis project. Analysis was performed in a 6-DOF motion analysis laboratory at a sampling frequency of 100 Hz. Thirty-four reflective markers were placed on each patient who underwent straight-line walking trials. Patients were stratified based on coronal Cobb angles (intervals of 10°), central sacral vertical line (coronal offset - CSVL; 10 mm interval), and curve location (right/left, thoracic/thoracolumbar curves. Evaluations of pelvic and thoracic motion in the axial plane were made between the control group and the AIS group. Calculations for axial motion, patterns of gait, and phase were performed with custom algorithms.
Results: Control subjects demonstrated a normal 'out of phase' gait pattern, which means that the pelvis and thorax rotated in opposite directions during the gait cycle. Pelvo-thoracic counter-rotation occurred twice during the gait cycle at right and left single limb stance (Figure1A+1B). Control subjects had a total pelvic rotation of 9.3° and a combined pelvo-thoracic rotation of 199°. AIS patients demonstrated reduction in normal thoracic-pelvic counter rotation. AIS patients with < 50° curves had mean maximal pelvo-thoracic counter-rotation significantly less than control patients (2.8° vs 7.1°; p = 0.03). AIS patients with >50° curves demonstrated no pelvo-thoracic counter-rotation at any point during gait with a mean maximal pelvo-thoracic counter-rotation of 0°, p = 0.006). No association between axial plane motion and the other radiograhic parameters (CSVL or curve type) were found. AIS patients demonstrated a mean 45% reduction in total pelvic rotation (5.2°) compared to controls (p < 0.001; Figure 1). AIS patients also demonstrated a mean 27% reduction in combined pelvic and thoracic rotation (145°) compared to controls (p < 0.05).
Conclusion: Structural changes in AIS patients are quantified using radiographic methods. The functional impact of structural changes is less understood. Our findings demonstrate that increasing curve severity is related to a dis-coordination in axial plane motion assessed using gait analysis. Increasing curve severity also results in a restricted gait pattern with a significant angular reduction in total pelvo-thoracic motion. These findings suggest that early diagnosis and treatment before large curve progression may prevent loss of physiologic gait and motion.