Revision of caged cervical intervertebral fusion / 中华骨科杂志

ABSTRACT

Objective To probe the reasons of failure of caged cervical intervertebral fusion and define the indications, operative techniques and short term results of the revision surgery. Methods Twenty-seven cases of caged cervical fusion were revised. The indication for fusion was cervical disc herniation in four cases and cervical spondylotic mylopathy in 23 cases. Of the 27 cases, there were 8 single levels, 15 double levels, 4 three levels. The intervals from revision to primary fusion were 2-25 months, 10.3 months in average. Patients presented discomfort (22 cases) and local pain of neck and shoulder (9 cases) or paralysis (19 cases) preoperatively. JOA grade was mean 11.6 points before revision. Radiographic examination showed the mean lordosis loss was 7.1 mm, the mean interbody height loss was 3.9 mm. 24 patients presented kyphosis. Occluded neighboring cages were found in multilevel cases. Nonunion was founded in 6 cases, unstable in 9 cases, compression still existed in 19 cases. Removal of cages and then decompression, bone grafting and anterior plating fixation were performed in 23 cases (29 cages). 16 patients underwent further posterior fixation. Posterior revisions underwent in another 4 cases (9 cages), including laminectomy and reshaping the lordosis and lateral mass screw plating fixation. Results All the cases were followed-up from 4 to 26 months, 11.7 months in average. The local symptoms released in 81% patients. Nerural deficit symptoms improved in 58% patients. Mean JOA grade was 14.2 points after revision. In 23 cases of anterior approach revisions, 17 cases obtained bone healing within 3 months, while 6 cases got delayed union. The kyphosis was corrected, and the intervertebral height increased 3 mm in average. There were no nerural impaction or failed internal fixation. Conclusion Deficient decompression, sinking of the cage into the cancellous bone of the vertebral body and subsequent kyphosis and bone graft nonunion consist of the main causes for revision surgery. The indications of revision are aggressive neurologic symptom, unstable or deformity of the cervical spine. Cage removal, completely decompression, bone grafting and secure fixation are major steps of revision procedure. In case of more than 3 fusion levels, further posterior fixation is advised.