Abstract
Introduction
We reported that excessive disc space distraction caused by insertion of large cages during anterior cervical discectomy and fusion (ACDF) induces adjacent segment degeneration (ASD). Previous reports indicated that over distraction of disc space was an independent risk factor for ASD after posterior lumbar interbody fusion. We therefore hypothesize that the incidence of ASD after ACDF with larger size of cages should be higher than that ACDF with normal cages due to this loss of disc space distraction.
Materials and Methods
Radiographic ASD is defined as development of spondylolisthesis >3 mm, decrease in disc height >3 mm, or intervertebral angle at flexion lesser than −5 degrees. Symptomatic ASD is defined by a decrease of ≥ 4 points in Japanese Orthopedic Association score. A 130 patients with cervical spondylotic radiculopathy were treated with either ACDF with larger size of cages (n = 45) or ACDF with normal cages (n = 85) and followed up for a minimum of 2 years (mean, 39.2 months).
Results
Disc space distraction in the normal cage group was significantly smaller (0.4 mm) as compared with the larger size group (1.8 mm). The incidence of clinical ASD in the normal cage group (2%, 1/45) was also significantly less than that in the larger size group (15%, 13/85). Multivariate analysis showed that disc space distraction was the most significant risk factor.
Conclusion
Among various risk factors for ASD after ACDF, the excessive distraction of disc space proved to be a potent risk factor for ASD.
None declared