Fig. 1

Measurement of radiological parameters: (a) the boundary of the endplate and the cage is delineated by yellow line. The tCS is defined as the sum of the cephalic CS (white line) and caudal CS (green line), and mCS is the larger one in them. DH is defined as the mean of the anterior DH (red line), middle DH (blue line), and posterior DH (pink line). (b) FH is measured by the perpendicular from the lower edge of the cephalic vertebra pedicle to the upper edge of the caudal vertebra pedicle. FH is the mean value of bilateral FH