Table 3. Summary of pre- and postoperative SSA(°) in relation to the levels involved.

No. of levels	Preop	Last postop	Mean increase in SSA
1-level	1.6±3.0	10.7±4.3	9.1±2.6
C4	0.8±2.0	8.7±4.0	7.9±2.2
C5	2.3±3.2	11.5±4.3	9.3±2.6
C6	0.5±2.1	9.5±4.1	9.0±2.8
C7	−1.5±0.7	8.0±1.4	9.5±2.1
2-level	7.2±5.1	16.7±3.2	9.4±3.4
C4–5	4.3±4.5	15.9±3.8	11.6±2.5
C5–6	11.2±2.4	17.8±1.9	6.4±1.8

No., number; SSA, sagittal segmental alignment; Preop, preoperative; Postop, postoperative.