OBJECTIVETo observe the relationship of adjacent segment degeneration and neck symptom after anterior cervical fusion.

METHODSMaking follow-up to 66 cases who had accepted anterior cervical fusion for 1 - 16 years, average 10.5 years. Observe the mobilization and gliding degree of adjacent segment in flexion-extension X-ray film, neck symptom, and the relationship of them. In 59 of these patients, the mobilization of entire cervical spine and non-fusion segment was observed before/after operation.

RESULTSThe incidence of adjacent segment instability in follow-up term was 72.7%, and 40.9% of all patients had significant neck symptom. The rate of significant neck symptom in patients who had instability was 48%, whereas which in patients without instability was 18.8%, and the difference was statistically significant (P < 0.05). The difference of mild instability and severe instability was not statistically significant (P > 0.1). The mobilization of entire cervical spine decreased obviously (P < 0.001). The mobilization of adjacent segment increased obviously (P < 0.01), and which of non-adjacent segment had no change (P > 0.05).

CONCLUSIONMajority of patients who have accepted anterior cervical fusion possessed instability of adjacent segment, but many of them have no symptoms. Adjacent segment instability is one of the reasons that induce neck symptoms.