Adjacent segment mobility after anterior cervical discectomy and fusion

Objective To investigate the mobility changes of adjacent segments after fusion retrospectively. Methods A total of 28 patients underwent standard anterior cervical arthrodesis. The kinematic changes occurred at segments adjacent to cervical arthrodesis through a coral bone graft and plating system. The mean follow-up period was 6. 3±1.6 years (3. 6 - 10. 5 ). Lateral radiographic views of cervical spine in flexion and extension were obtained at pre-operation and follow-up. Rotational motion at adjacent levels was quantified. Results Sagittal range of motion ( ROM ) at adjacent cranial level was 11.2°± 5.0° at pre-operation and 11.4°± 6.4°at follow-up. It was not statistically significant ( P ＞ 0. 01 ).At adjacent caudal level, ROM was 9. 8°±5. 3°, but 10. 2°±4. 6°at follow-up. But it was not statistically significant ( P ＞0. 01 ). During the follow-up, entire cervical motion ( C2-C7 ) decreased significantly from 46. 8°± 13.4° to 36. 8°± 9. 6° in single-level fusion group, but from 48.6°± 14. 6° to 39. 9°± 7. 2° in double-level fusion group. Conclusion The assumption of an iatrogenically elevated adjacent level mobility by cervical fusion is refuted by the present study. Key words: Cervical vertebrae;  Spinal fusion;  Range of motion,articular