Incidence and Risk Factors of Cervical Kyphosis in Patients with Adolescent Idiopathic Scoliosis.

BACKGROUND

Cervical kyphosis (CK) has been reported in patients with adolescent idiopathic scoliosis (AIS). The report about the incidence of CK between patients with AIS and normal populations was little. Patients included in previous studies often required scoliosis surgery (Cobb angle ≥40°), which does not represent all patients with AIS. The aims of this study were to compare incidence of CK between patients with AIS (Cobb angle >10°) and an age-matched normal population and to identify risk factors related to CK, especially coronal parameters that have rarely been studied in current literature.

METHODS

Patients with AIS (n = 112) and asymptomatic subjects from the general population (control group; n = 40) were retrospectively analyzed. Radiographic parameters of coronal and sagittal plane were measured on full-length spine x-rays. Patients with AIS were divided into 2 groups based on cervical lordosis angle: cervical lordosis and CK.

RESULTS

CK was observed in 14 of 40 (35%) subjects in the control group and 68 of 112 (60.7%) patients with AIS. Several parameters were related to CK, including major curve, proximal thoracic, and main thoracic Cobb angle; proximal thoracic kyphosis angle; main thoracic kyphosis angle; T1 slope; sagittal vertical axis; vertical distance between C7 plumb line and center sacral vertical line; apical vertebral translation; T1 coronal tilt; and lumbar pelvic relationship. Logistic regression identified main thoracic Cobb angle, main thoracic kyphosis angle, sagittal vertical axis, lumbar pelvic relationship, and apical vertebral translation as independent risk factors of CK.

CONCLUSIONS

Incidence of CK increases in patients with AIS relative to normal subjects. Coronal parameters of the spine could influence cervical sagittal alignment.