Sagittal balance parameters in achondroplasia

•The lumbar lordosis angle of the balanced spine is larger than that of the imbalanced patients.•A significant positive correlation between the sacral slop and lumbar lordosis angle is found in balanced groups, indicating the compensation of the increased LL for the SS, which is larger than the reported values of the SS in non-achondroplasts.•In patients with an imbalanced spine, there is a strong negative correlation between lumbar lordosis and thoracolumbar angle, denoting that the LL fails to compensate for thoracolumbar kyphosis. This correlation is likewise negative in the balanced patients, but with moderate strength.