The morphological abnormalities of pedicles and spinal canal in the apical region of adolescent idiopathic thoracic scoliosis

English Keywords:Adolescent idiopathic scoliosis  The apical region  Pedicle  Spinal canal

English Abstract:

  【Abstract】 Objectives: To investigate the morphological characteristic of thoracic pedicles and spinal canal in the apical region of idiopathic thoracic scoliosis and its influence on the accuracy of pedicle screw placement. Methods: 28 adolescent idiopathic scoliosis(AIS) patients with the apical vertebra at T8 and 13 age-matched controls were included in this study from June 2008 to September 2010. Standard up-standing posteroanterior whole spine radiography was performed to investigate the Cobb angle of main thoracic curve and the vertebral translation(VT) of each vertebra in the apical region(T7-T9). Furthermore, CT scanning was also performed to investigate the morphological parameters of pedicles and spinal canal of each vertebra, which included the axial section area of spinal-canal(ASA), the sagittal diameter of the spinal-canal(SDS), the coronal diameter of the spinal-canal(CDS), the transverse pedicle diameter(TPD) and the angle between bilateral pedicles(ABP). Independent samples t-test analysis and multiple linear regression analysis were performed to determine the differences of the above morphological parameters between the two groups, and the correlations between the investigated morphological parameters in AIS group were investigated. Results: The ASA, CDS and ABP were significantly larger in AIS patients than those in controls(P<0.05); while TPD of AIS patients in concave side was significantly thinner than that in controls(P<0.05). No significant difference was found in the comparison of the SDS and the TPD in convex side between the two groups. In addition, the results showed that the CDS was correlated with the VT(T7: Beta=0.094, P=0.022; T8: Beta=0.630, P=0.005; T9: Beta=0.119, P=0.014); while no significant correlations were found between the ABP or the TPD in concave side and the gender, age, VR and VT of AIS patients. Conclusions: The ASA, CDS and ABP are significantly larger in AIS patients than those in controls, while the TPD of AIS patients in concave side is significantly thinner than that in controls, which may be a potential risk factor for pedicle screw resplacement.