Abstract: BACKGROUND: Most scholars now believe that children with cerebral palsy who have severe spinal deformities in early childhood (< 15 years of age) may have a higher risk of progression of spinal deformities, which may result from imbalances in movement due to pelvic tilt, pain, etc.
OBJECTIVE: To investigate the relationship between lumbar spine development and hip joint development in children with spastic cerebral palsy. 
METHODS: A retrospective analysis was performed in 102 children with spastic cerebral palsy admitted at Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine from January 2014 to December 2021. All admitted children had X-rays of the pelvic position and the lumbar lateral position. Anteroposterior X-ray of the pelvis was performed to measure femoral head migration percentage, central edge angle, neck-shaft angle, and acetabular index. The sagittal Cobb angle, sacral slope, arch-top distance, and lumbar lordosis index were measured by the lateral X-ray of the lumbar spine. Correlation of the two sets of indicators was further analyzed. All children were divided into normal group, risk group, hip subluxation group and total hip dislocation group according to their femoral head migration percentage, and the differences in lumbar spine indexes between groups were evaluated.  
RESULTS AND CONCLUSION: Pearson correlation analysis showed that the femoral head migration percentage was moderately positively correlated with sagittal Cobb angle and arch-top distance, and weakly positively correlated with lumbar lordosis index; the central edge angle was moderately negatively correlated with the arch-top distance and weakly negatively correlated with the sagittal Cobb angle; the neck-shaft angle was weakly positively correlated or not correlated with the sagittal Cobb angle and lumbar lordosis index; and the acetabular index was weakly positively correlated with the sagittal Cobb angle and arch-top distance. No statistically significant correlation was found between the remaining indicators. According to the femoral head migration percentage, the children were divided into four groups, including 25 cases in the normal group, 41 cases in the risk group, 27 cases in the hip subluxation group, and 9 cases in the total hip dislocation group. The sagittal Cobb angle was significantly increased in the risk group, the hip subluxation group and the total hip dislocation group compared with the normal group, showing an increasing trend group by group, and there were significant differences between groups (P < 0.05). Compared with the normal group, the lumbar lordosis index in the risk group and the hip subluxation group increased significantly, and there were significant differences between groups (P < 0.05). There was an increase trend in the lumbar lordosis index of the total hip dislocation group compared with the normal group. Compared with the normal group, the arch-top distance in the hip subluxation group and the total hip dislocation group increased significantly (P < 0.05), and there was a stepwise increasing trend. There was no significant difference in sacral slope between groups. To conclude, the development of the lumbar spine in children with cerebral palsy is closely related to the development of the pelvic hip joint, and the most obvious relationship is between lumbar lordosis and hip dislocation.

Key words: cerebral palsy, hip dislocation, pelvic deformities, lumbar deformity, lumbar sagittal Cobb angle, femoral head migration percentage