Annual changes in radiographic indices of the spine in cerebral palsy patients.

PURPOSE: We estimated the annual changes in radiographic indices of the spine in cerebral palsy (CP) patients and analyzed the factors that influence its progression rate.

METHODS: We included CP patients who had undergone whole-spine radiography more than twice and were followed for at least 1 year. The scoliosis Cobb angle, coronal balance, apical vertebral translation, apical rotation, and pelvic obliquity were measured on anteroposterior (AP) radiographs; thoracic kyphosis and lumbar lordosis angles, and sagittal balance was measured on lateral radiographs; and migration percentage was measured on AP hip radiographs to determine hip instability. For each gross motor function classification system (GMFCS) level, the Cobb angles, apical vertebral translation, coronal and sagittal balance, and pelvic obliquity were adjusted by multiple factors with a linear mixed model.

RESULTS: A total of 184 patients (774 radiographs) were included in this study. There was no significant annual change in scoliosis Cobb, thoracic kyphosis, and lumbar lordosis angles in the GMFCS level I-II and III groups. In the GMFCS level IV-V group, there was an annual increase of 3.4° in the scoliosis Cobb angle (p = 0.020). The thoracic kyphosis angle increased by 2.2° (p = 0.018) annually in the GMFCS level IV-V group. Apical vertebral translation increased by 5.4 mm (p = 0.029) annually in the GMFCS level IV-V group. Progression of coronal and sagittal balance and pelvic obliquity with aging were not statistically significant. Sex, hip instability, hip surgery, and triradiate cartilage did not affect the progression of scoliosis and the balance of the spine and pelvis.

CONCLUSIONS: The scoliosis Cobb angle, thoracic kyphosis angle, and apical vertebral translation in the GMFCS level IV-V CP patients progressed with age. These findings can predict radiographic progression of scoliosis in CP patients.