A Radiographic Analysis of Cervical Sagittal Alignment in Adolescent Idiopathic Cervical Kyphosis

The aim of this study was to analyze the radiologic features of adolescent idiopathic cervical kyphosis.

There are few previous reports about radiographic analysis of cervical sagittal alignment of adolescent idiopathic cervical kyphosis. A new method was proposed in this article to evaluate the severity of cervical kyphosis.

A total of 41 adolescent patients with cervical kyphosis were reviewed. Several angles were measured from the radiographs utilizing the 2-line Cobb method and Harrison posterior tangent method. Ishihara's Curvature Index (CI), Kyphosis Index (KI), kyphosis levels, and the apex of the kyphosis were also measured.

The results showed that the apex of the kyphosis is located at the posterior-superior edge of C4 (70.7%) and C5 (29.3%). C2-C7 angles ranged from 4.7 to 71.3 degrees (36.2±13.6 degrees) and from 9.8 to 83.1 degrees (36.4±15.1 degrees) in the above 2 methods, respectively. Local angles of kyphotic area ranged from 21.8 to 96.3 degrees (50.5±23.7 degrees) in 2-line Cobb method and from 19.8 to 105.6 degrees (52.0±19.5 degrees) in Harrison posterior tangent method. CI and KI ranged from 8.6 to 79.8 (36.8±16.7) and 15.2 to 141.9 (50.6±23.7), respectively. Statistical analysis showed that there was significant positive correlation between KI and kyphosis angle.

In adolescent idiopathic cervical kyphosis, the alteration of the sagittal profile only occurs on partial cervical alignment rather than the whole cervical spine. The apex of the kyphosis locates at posterior-superior edge of the vertebrae. It seems that KI can accurately depict the severity of cervical kyphosis.