Early Outcomes of Multilevel ACDF With Segmental Plate Fixation.

Abstract

Case series: retrospective review of prospectively collected data. To study the outcomes of segmental plate fixation in multilevel ACDF. Multilevel ACDF constructs with a single contiguous plate have higher rates of pseudoarthrosis, dysphagia, and mechanical failure compared with single-level fusions. The use of low-profile single-segment plates in series (segmental ACDF) has been proposed as a means of making multilevel anterior fixation more facile while avoiding the biomechanical limitations of "stand-alone" integrated fixation implants. We prospectively followed consecutive patients undergoing multilevel segmental ACDF to 1-year follow-up. Fusion was assessed through evaluation of bridging bone and interspinous movement (ISM, <2 mm) on flexion/extension x-rays. When available, CT was used to confirm fusion grading. Subsidence was assessed using change in segmental height (>2 mm). Ninety-one patients (222 levels) were analyzed. Significant improvements in both pain and disability were observed (mean NDI preop=34.9, 1-y postop=16.6, P<0.001). Average change in cervical (C2-7) and segmental lordosis from preop to postop was 7.3 degrees (P<0.001) and 4.4 degrees (P<0.001), respectively. The rate of fusion at one year was 94.6% by bony bridging and 86.0% by ISM (<2 mm). CT was available in 9 of the 31 levels with ISM >2, and fusion was observed in 7/9 (77.7%) of these cases. Subsidence was present in 9.5% of levels, occurring most often at C6/7. Importantly, there was no association between number of levels treated and the likelihood of pseudoarthrosis or subsidence at an individual level. Segmental plating in multilevel ACDF is safe and leads to sustained improvements in disability, pain, and alignment, with fusion rates comparing favorably to traditional plating. In contrast to stand-alone implants, multilevel segmental ACDF led to alignment and subsidence results consistent with traditional plating. Unlike traditional ACDF, the number of levels treated did not seem to influence rates of pseudoarthrosis and subsidence.