Changes of Adjacent Segment in Anterior Cervical Fusion

Park, Heui Jeon; Kim, In Gu; Kim, Wan Ki

Abstract

STUDY DESIGN: A retrospective radiographic and medical record analysis of 36 patients.
OBJECTIVES
To describe the incidence and consequence of the distribution of sagittal plane motion, across the adjacent cervical motion segment, after cervical fusion. Furthermore, to find the cause of the progression of degenerative changes in intervertebral discs adjacent to the fused segment. SUMMARY OF LITERATURE REVIEW : Anterior cervical fusion has been widely used in the treatment of degenerative cervical spine. An increased incidence of degenerative disease may exist at the levels immediately adjacent to a cervical fusion. However, the frequency of these complications is probably overestimated, and their effect on clinical outcome remains unknown.
MATERIALS AND METHODS
From 1990 to 1996, 36 patients who underwent anterior cervical spine fusion for degenerative disorders were reviewed retrospectively with an average follow up of 6.9 years. Lateral views in neutral position, in flexion, and in extension of the preoperative cervical roentgenograms were analyzed in comparison with the last follow-up films in the range of motion of the neck, and in the intervertebral angular mobility and anteroposterior displacement of the vertebral bodies, and finally to quantify the incidence of the spinal instability.
RESULTS
Degenerative change in adjacent intervertebral level was observed in 16 of the 36 patients (44.4%), above the fusion in 10, below the fusion in 4, and both above and below the fusion in 2 cases. In addition, degenerative change in adjacent intervertebral level was observed in 68% of cases of loss of lordosis of the fused segment, and degenerative change occurred more frequently in younger patients to a statistically significant extent.
CONCLUSIONS
Loss of lordosis of the fused segment and young age are two factors promoting degenerative changes in adjacent intervertebral levels after anterior cervical fusion.