Influence of lumbar curvature and rotation on forward flexibility in idiopathic scoliosis

Lumbar spine facet joints are arranged sagittally and mainly provide forward flexibility. Rotation of the lumbar vertebral body and coronal plane deformity may influence the function of lumbar forward flexibility. We hypothesize that the more advanced axial and coronal plane deformity could cause more limitation on forward flexibility in patients with idiopathic scoliosis.

Between January 2011 and August 2011, 85 patients with adolescent idiopathic scoliosis were enrolled in this study. The proximal thoracic, major thoracic, thoracolumbar/lumbar (TL/L), and lumbar (L1/L5) curves were measured by Cobb's method. Lumbar apical rotation was graded using the Nash-Moe score. Lumbar forward flexibility was measured using the sit and reach (S and R) test. Statistical analysis was performed using one-way analysis of variance (ANOVA), Spearman's and Pearson's correlation coefficients.

The mean age was 16.1 ± 2.84 years. The mean proximal thoracic, major thoracic, TL/L, and L1/L5 curves were 17.61° ± 8.92, 25.56° ± 11.61, 26.09° ± 8.6, and 15.10° ± 7.85, respectively. The mean S and R measurement was 25.56 ± 12.33 cm. The magnitude of the TL/L and L1/L5 curves was statistically positively related to vertebral rotation (r(s) = 0.580 and 0.649, respectively). The correlation between the S and R test and both the TL/L and L1/L5 curves was negative (r(p) = -0.371 and -0.595, respectively). Besides, the S and R test also demonstrated a significant negative relationship with vertebral rotation (rs = -0.768).

In patients with idiopathic scoliosis, spinal deformity can diminish lumbar forward flexibility. Higher lumbar curvature and rotation lead to greater restriction of lumbar flexion.