PMC4628194_01
a: Plain lateral radiograph of the preoperative cervical spine showing 43  kyphosis (C2-C7 Cobb angle). b: Plain lateral radiograph of the postoperative cervical spine showing 4  kyphosis at the level of C2-C7; a correction of 39  was achieved. c: Plain lateral radiograph of the preoperative total spine; C7 plumb line was displaced posteriorly, and SVA was -56 mm. d: Plain lateral radiograph of the postoperative total spine; C7 plumb line was shifted anteriorly, and sagittal alignment approached neutral balance. SVA was diminished to -4 mm. SVA: sagittal vertical axis.
nmc-55-599-g1.jpg
PMC4628194_01_nmc-55-599-g1.jpg
F1
A plain radiograph in a neutral position revealed a 43  kyphosis of C2-C7 Cobb angle (Fig. 1a), and the kyphotic angle changed to 25  in extension and 53  in flexion. Cervical spine alignment improved to 2  kyphosis (C2-7 Cobb angle); a 40  correction was achieved immediately after surgery, and maintained (3  kyphosis: C2-7 Cobb angle) at the last (66 months) follow-up (Fig. 1b). The distance between the C7 plumb line and the superior posterior corner of S1 (sagittal vertical axis, SVA) was -56 mm preoperatively and -4 mm postoperatively (Fig. 1c, d), indicating an improvement of the total spine sagittal alignment that was maintained at the last (66 months) follow-up.
PMC4628194_02
a: Plain lateral radiograph of the preoperative cervical spine showing 35  kyphosis (C2-C7 Cobb angle). b: Plain lateral radiograph of the postoperative cervical spine showing 8  lordosis at the level of C2-C7; a correction of 43  was achieved. c: Plain lateral radiograph of the preoperative total spine; C7 plumb line was displaced posteriorly, and SVA was -50 mm. d: Plain lateral radiograph of the postoperative total spine; C7 plumb line was shifted anteriorly, and sagittal alignment approached neutral balance. SVA was diminished to 0 mm. SVA: sagittal vertical axis.
nmc-55-599-g2.jpg
PMC4628194_03_nmc-55-599-g2.jpg
F2
The SVA was -115 mm preoperatively and -58 mm postoperatively (Fig. 2c, d).
PMC4628194_03
a: Plain lateral radiograph of the preoperative cervical spine showing 35  kyphosis (C2-C7 Cobb angle). b: Plain lateral radiograph of the postoperative cervical spine showing 8  lordosis at the level of C2-C7; a correction of 43  was achieved. c: Plain lateral radiograph of the preoperative total spine; C7 plumb line was displaced posteriorly, and SVA was -50 mm. d: Plain lateral radiograph of the postoperative total spine; C7 plumb line was shifted anteriorly, and sagittal alignment approached neutral balance. SVA was diminished to 0 mm. SVA: sagittal vertical axis.
nmc-55-599-g2.jpg
PMC4628194_03_nmc-55-599-g2.jpg
F2
The SVA was -115 mm preoperatively and -58 mm postoperatively (Fig. 2c, d).
a: Plain lateral radiograph of the preoperative cervical spine showing 23  kyphosis (C2-C7 Cobb angle). b: Plain lateral radiograph of the postoperative cervical spine showing 16  lordosis at the level of C2-C7; a correction of 39  was achieved. c: Plain lateral radiograph of the preoperative total spine; C7 plumb line was significantly displaced posteriorly, and SVA was -115 mm. d: Plain lateral radiograph of the postoperative total spine; C7 plumb line was shifted anteriorly, and SVA was shortened to -58 mm. SVA: sagittal vertical axis.
nmc-55-599-g3.jpg
PMC4628194_03_nmc-55-599-g3.jpg
F3
A 71-year-old woman presented with cervical kyphotic deformity (C2-C7 Cobb angle: kyphosis 23 ) after a laminectomy for cervical spondylotic myelopathy (Fig. 3a). The sagittal balance of the cervical spine improved to 19  lordosis (C2-7 Cobb angle), a 42  correction was achieved immediately after surgery, and the alignment was maintained (16  lordosis: C2-7 Cobb angle) at the last follow-up (61 months) (Fig. 3b).