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.