Background: Studies suggest that the annual incidence of symptomatic adjacent segment disease is 2-3%. Because biomechanical studies have shown increased stress at levels adjacent to a fusion mass, some surgeons have advocated including the normal level in the fusion construct in patients presenting with noncontiguous cervical spondylosis requiring surgical intervention. Our objective was to evaluate the incidence of adjacent segment disease (ASD) in intermediate segments in noncontiguous anterior cervical fusion.
Method: We reviewed patients who underwent noncontiguous anterior cervical arthrodesis between 1985 and 2007. The primary outcome was the presence of symptomatic degeneration at the intermediate segment in noncontiguous fusions. Secondary outcomes were visual analog scale (VAS) scores and overall neurologic outcome.
Results: Seventeen cases of noncontiguous anterior cervical fusion were included. None had symptomatic ASD at the intervening level during mean follow-up of 26 months. Thirteen of 17 patients demonstrated postoperative neurological improvement; four had no change. Overall symptomatic outcome was judged as significantly improved, moderately improved, and unchanged in 11, two, and four patients, respectively. A mean five-point improvement in the VAS score was seen at 3-month follow-up, with continued improvement at 24 months. Among the 37 levels fused, three levels in two patients showed evidence of pseudarthrosis, one of which remained asymptomatic during the follow-up period.
Conclusions: We observed neurological and clinical overall improvement in our series of patients after noncontiguous fusions without evidence of increased degeneration requiring treatment at the intermediate segment. We believe this technique is safe and effective without increased postoperative or long-term morbidity.