Table 2.

The characteristics of the 21 levels fused when there were discrepancies about assessing fusion between the flexion–extension radiographs and extension CT images when fusion was affirmed on flexion–extension radiographs

	N	%
The number of fusion levels
1-level fusion	15	22.1% of single-level fusion
2-level fusion	4	40.0% of two-level fusion
3-level fusion	2	66.7% of three-level fusion
The type of interbody reconstruction
Metal cage	15	29.4% of metal cage used cases
Autologous iliac crest bone graft	6	20% of iliac crest bone used cases