[Early outcome of using Zero-profile implant system in treatment of cervical spondylosis]

To evaluate the early outcome of anterior cervical discectomy and fusion (ACDF) using a Zero-profile implant system (Zero-P) for interbody fusion in the treatment of cervical spondylosis.

Between March 2010 and June 2011, 25 patients with cervical spondylosis underwent ACDF with Zero-P. There were 13 males and 12 females with an average age of 44.2 years (range, 26-67 years), including 14 cases of nerve root cervical spondylosis, 6 cases of spinal cervical spondylosis, and 5 cases of mixed cervical spondylosis. The disease duration was 3-120 months (median, 25 months). Single segment was involved in 20 cases, 2 segments in 4 cases, and 3 segments in 1 case. A total of 31 Zero-P were implanted (3 at C3, 4, 8 at C4, 5, 12 at C5, 6, and 8 at C6, 7). Primary cervical operation was performed in 23 cases and re-operation in 2 cases. Before and after operation, the height of intervertebral space and the cervical Cobb angle were measured; clinical outcome was evaluated using visual analogue scale (VAS) score for pain in the neck and upper limb, and Japanese Orthopaedic Association (JOA) score for myelopathy; and intervertebral fusion and the incidence of dysphagia were also observed.

All incisions healed by first intention. All the patients were followed up 12-16 months (mean, 13.9 months). Interbody bone fusion was obtained, and the fusion time was 2.7-6.0 months (mean, 3.8 months). Three patients had dysphagia after operation; symptom disappeared at 1 week and 3 months after operation in 2 cases and 1 case, respectively. No fixation loosening, subsidence, or breakage occurred. The height of intervertebral space was significantly improved (P < 0.05) from (4.5 +/- 0.5) mm at preoperation to (6.0 +/- 0.7) mm at 1 week and (5.7 +/- 0.6) mm at 12 months after operation; the cervical Cobb angle was significantly improved (P < 0.05) from (11.9 +/- 6.1) degrees at preoperation to (21.2 +/- 4.1) degrees at 1 week and (20.2 +/- 3.7) degrees at 12 months after operation; and there was no significant difference between at 1 week and 12 months after operation (P > 0.05). The VAS score was significantly reduced (P < 0.05) from 7.1 +/- 0.8 at preoperation to 1.9 +/- 0.8 at 3 months and 1.0 +/- 0.5 at 12 months after operation; the JOA score was significantly increased (P < 0.05) from 9.6 +/- 1.3 at preoperation to 13.5 +/- 1.0 at 3 months and 14.9 +/- 1.0 at 12 months after operation; and there was significant difference between at 3 months and at 12 months after operation (P < 0.05).

The early outcome of ACDF using a Zero-P in the treatment of cervical spondylosis is satisfactory and reliable, and it can restore and maintain the cervical alignment and disc height, and disc has low incidence of postoperative dysphagia.