Degenerative Changes of Adjacent Segment after Anterior Cervical Discectomy and Fusion

Abstract

Study Design: A retrospective radiologic analysis of 34 patients Objectives: To evaluate the factors influencing the radiographic degenerative changes in the adjacent segments in one-level ACDF (ed note: define ACDF). Summary of Literature Review: There is a 25% incidence of adjacent segment degeneration after 5 years. Materials and Method: From 2002 to 2005, 34 patients (male 23, female 11) underwent anterior cervical spine fusion using a cage or bone block for degenerative cervical spine. The mean age of the patients was 51 years and the mean follow-up period was 24 months. The degenerative findings of the upper and lower adjacent segment were measured from the pre-operative MRI. The fused segment curvature, disc heights of the adjacent segments, displacement of the vertebral bodies and angular mobility in the adjacent segments were measured from the pre-operative and final follow-up lateral views in the neutral position, in both flexion and extension. Results: Degenerative changes in the adjacent segments were observed in 19 of the 34 patients. The group with degenerative changes showed significantly more lordotic angular loss of the fusion segments (11.9±3.1�) at the follow-up observation than the group with no degenerative changes (9.0±1.1�) (p=0.04). The group with degenerative change showed a significantly larger increase in disc height of the fusion segments (2.8±0.2 mm) at the follow-up observation than the group with no degenerative changes (2.2±0.3 mm) (p=0.02).The group with a Grade IV or higher level of pre-operative disc degeneration showed more degenerative changes in the adjacent segments than those with Grade III or lower. Conclusions: It is important to preserve the lordotic angle of fused segments and avoid excessive increases in disc height. The recurrence of the neurological is not associated with the preoperative adjacent segmental degenerative changes in ACDF.