Effect analysis of anterior cervical operation for severe cervical kyphosis

Objective To determine the feasibility and safety of anterior cervical decompression and fusion in severe cervical kyphosis treatment. Methods Totally 29 patients with severe cervical kyphosis(Cobb angle>50°) underwent anterior cervical decompression and fusion from June 2008 to May 2016 were studied retrospectively. There were 19 males and 10 females. The average age was 32.6 years ranging from 14 to 53 years. According to the etiology, 12 patients had iatrogenic deformity (11 had post-laminectomy cervical kyphosis, 1 had kyphosis due to anterior graft subsidence), 5 had neurofibromatosis, 4 had infective kyphosis, 8 had idiopathic cervical kyphosis. The curvature of cervical angle was measured by two-line Cobb method. The severity of cervical kyphosis was evaluated by kyphosis index (KI). Parameters including kyphosis levels, the apex of the kyphosis, C2-7 sagittal vertical axis(SVA) and T1 slope were also measured on lateral radiographs in the neutral position in each patient. The pre- and post-operative Japanese Orthopaedic Association(JOA) scores, visual analogue scale (VAS) of neek pain, neck disability index (NDI) and cervical alignment were compared. All patients were treated by skull traction. Motor evoked potential and somatosensory evoked potential were applied intraoperation as the spinal cord monitor. Results Skull traction was performed for an average of 6.3 days. The mean vertebral number in kyphotic region was 4.7. The average operation time was 155 minutes and blood loss was 135 ml. The preoperative C2-7Cobb angle was 46.6°±18.1° in average. It was reduced to 11.4°±6.4° in average after operation. The Cobb angle of operation region was 72.9°±19.6° in average before operation. It was reduced to 11.2°±6.4° in average after operation. The kyphosis region correction rate was 84.6%. The mean preoperative C2-7SVA changed from (3.8±14.6) mm to (12.6±7.8) mm postoperatively. The mean preoperative T1 slope changed from -10.6°±16.4° to 7.1°±14.9° postoperatively. The average postoperative C2-7 Cobb angle, Cobb angle of kyphosis region, KI, C2-7 SVA and T1 slope changed significantly compared with preoperation (F=12.700-218.200, all P<0.01). The average postoperative JOA, VAS and NDI scores improved significantly compared with preoperation (F=225.500, 217.900, 131.200, all P<0.01). Conclusion For severe cervical kyphosis, anterior correction is a safe and effective technique, sufficient decompression will be achieved. Key words: Cervical vertebrae; Kyphosis; Anterior cervical operation