Comparison of Disc and Vertebral Wedging Between Patients With Adolescent Idiopathic Scoliosis and Chiari Malformation-associated Scoliosis

Study Design A comparative study. Objective To investigate the difference of disc and vertebral wedging between patients with adolescent idiopathic scoliosis (AIS) and Chiari malformation-associated scoliosis (CMS). Summary of Background Data The wedging of disc and vertebral wedging of AIS are well investigated. However, the comparison of that wedging between AIS and CMS is not found in the literature. Method This study included 35 cases of AIS and 31 cases of CMS. The disc and vertebral wedging was measured by Cobb method. The percentage of single disc and vertebral wedging in the whole thoracic or lumbar curve was calculated. The difference between disc and vertebral wedging, the apical vertebra and average adjacent vertebrae wedging, the apical discs and adjacent discs wedging in the same curve location, same diagnosis and similar Cobb angle group was compared. The difference of disc or vertebral wedging between AIS and CMS, Cobb angle <60 degrees and ≥60 degrees was also compared. The correlation between the apical vertebral wedging angle and Cobb angle was performed by Pearson correlation analysis. Results The difference between disc and vertebral wedging in the same curve location, same diagnosis, and similar Cobb angle group was statistically significant (P<0.05). No significant difference of the disc or vertebral wedging was found between AIS and CMS in the same curve location and the similar Cobb angle group (P>0.05). No significant difference of the disc or vertebral wedging was found between Cobb angle <60 degrees and ≥60 degrees groups in the same curve location and the same diagnosis (P>0.05). There was a positive correlation between the apical vertebra wedging angle and Cobb angle in AIS patients and CMS patients. The wedging of apical vertebra and disc was more than that in the adjacent disc and vertebra in the same curve. Conclusions The relative wedging of intervertebral disc and vertebrae with AIS patients is similar to that of scoliosis with known cause (CMS). The wedging of discs and vertebrae in AIS patients may be an adaptive change secondary to some extravertebral factors.