Global postural re-education in pediatric idiopathic scoliosis: a biomechanical modeling and analysis of curve reduction during active and assisted self-correction

Background: Global postural re-education (GPR) is a physiotherapy treatment approach for pediatric idiopathic scoliosis (IS), where the physiotherapist qualitatively assesses scoliotic curvature reduction potential (with a manual correction) and patient's ability to self-correct (self-correction). To the author's knowledge, there are no studies regarding GPR applied to IS, hence there is a need to better understand the biomechanics of GPR curve reduction postures. The objective was to biomechanically and quantitatively evaluate those two re-education corrections using a computer model combined with experimental testing. Methods: Finite elements models of 16 patients with IS (10.5-15.4 years old, average Cobb angle of 33 degrees) where built from surface scans and 3D radiographic reconstructions taken in normal standing and self-corrected postures. The forces applied with the therapist's hands over the trunk during manual correction were recorded and used in the FEM to simulate this posture. Self-correction was simulated by moving the thoracic and lumbar apical vertebrae from their presenting position to their self-corrected position as seen on radiographs. A stiffness index was defined for each posture as the global force required to stay in the posture divided by the thoracic curve reduction (force/Cobb angle reduction). Results: The average force applied by the therapist during manual correction was 31 N and resulted in a simulated average reduction of 26% (p < 0.05), while kyphosis slightly increased and lordosis remained unchanged. The actual self-correction reduced the thoracic curve by an average of 33% (p < 0.05), while the lumbar curve remained unchanged. The thoracic kyphosis and lumbar lordosis were reduced on average by 6 degrees and 5 degrees (p < 0.05). Self-correction simulations correlated with actual self-correction (r = 0.9). Conclusions: This study allowed quantification of thoracic curve reducibility obtained by external forces applications as well as patient's capacity to self-correct their posture, two corrections commonly used in the GPR approach.