Abstract: BACKGROUND: The majority of studies on developmental dysplasia of the hip focus on hip malformations, but there are few reports on the effects of acetabular dysplasia on the spine.  
OBJECTIVE: To investigate the compensation of spinopelvic parameters in coronal and sagittal views in patients with developmental dysplasia of the hip, and to explore the correlation between acetabular development and spinopelvic parameters.
METHODS: A total of 101 patients with developmental dysplasia of the hip admitted to the Third Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2018 to June 2022 were selected as the trial group, and 114 healthy subjects were selected as the control group during the same period. The spinopelvic parameters of the subjects were measured through the full-length X-ray films of the coronal and sagittal spines: lumbar lordosis, anterior pelvic tilt, thoracolumbar kyphosis, Cobb angle, and the distance between the C7 plumb line and the center sacral vertical line, sacral slope, pelvic incidence, and thoracic kyphosis. The differences in spinopelvic parameters were compared between the two groups. In addition, the differences in spinopelvic parameters in patients with unilateral, bilateral and different Crowe classifications of developmental dysplasia of the hip were compared. Pearson correlation analysis was used to explore the correlation between Sharp angle and spinopelvic parameters.  
RESULTS AND CONCLUSION: (1) In the sagittal view, the lumbar lordosis in the trial group was significantly lower than that in the control group (P < 0.05). The pelvic tilt and kyphosis angle of the thoracolumbar segment in the trial group were significantly greater than those in the control group (P < 0.05). In the coronary position, the Cobb angle and the distance between the C7 plumb line and center sacral vertical line in the trial group were significantly greater than those in the control group (P < 0.05). There was no significant difference in the remaining spinopelvic parameters between the two groups (P > 0.05). (2) The lumbar lordosis of patients with bilateral developmental dysplasia of the hip was significantly lower than that of patients with unilateral developmental dysplasia of the hip (P < 0.05). The pelvic tilt, thoracolumbar kyphosis, Cobb angle and the distance between the C7 plumb line and center sacral vertical line in bilateral developmental dysplasia of the hip patients were significantly greater than those in unilateral developmental dysplasia of the hip patients (P < 0.05). (3) The lumbar lordosis decreased with the increase of Crowe classification severity (P < 0.05). The pelvic tilt increased with the severity of the Crowe classification (P < 0.05). (4) Pearson correlation analysis showed that Sharp angle was negatively correlated with lumbar lordosis (P < 0.05), while Sharp angle was positively correlated with anterior pelvic tilt, Cobb angle, C7 plumb line and center sacral vertical line (P < 0.05). (5) It is concluded that the pelvic tilt, thoracolumbar kyphosis, Cobb angle and the distance between the C7 plumb line and center sacral vertical line increase, while lumbar lordosis decreases in developmental dysplasia of the hip patients. The degree of acetabular dysplasia was significantly correlated with lumbar lordosis, pelvic tilt, Cobb angle, C7 plumb line and center sacral vertical line.

Key words: acetabulum development degree, developmental dysplasia of hip, spinopelvic parameter, compensation, relevance, side bend