2020 Impact of Supplemental Posterior Stabilization on Progression of Fusion in the Treatment of Three Level Cervical Degenerative Disc Disease: Results from a Prospective Randomized FDA IDE Trial

INTRODUCTION: Achieving complete arthrodesis with anterior cervical discectomy and fusion (ACDF) helps ensure sustained relief of symptoms with outcomes at 2 years being a strong indicator of long-term success. One risk factor for pseudarthrosis is multi-level treatment. The FUSE Clinical Trial was designed to understand how addition of tissue-sparing supplemental posterior fusion (PCF) to ACDF improves outcomes when treating three level disease. METHODS: Investigators in the FUSE Clinical Trial enrolled subjects with symptoms resulting from degenerative disc disease at three contiguous cervical levels. Subjects were randomized to receive either ACDF alone or CCF (ACDF with supplemental PCF). Subjects returned at 12 and 24 months for radiographic studies (dynamic x-ray and CT) to determine fusion. Fusion success was defined as all three segments achieving a range of motion less than 2° with CT confirming bridging bone across each segment. Radiographic outcomes were determined from an independent imaging lab. RESULTS: At this interim analysis, 116 subjects completed the study (59 CCF, 57 ACDF). Complete arthrodesis was observed in 74.6% of CCF subjects and 33.3% of ACDF subjects (p<0.001). Of the subjects with month 24 success, 91.1% of CCF subjects achieved success by the earlier month 12 visit compared to 35% of ACDF subjects. For CCF subjects with incomplete fusion at study conclusion, 81.8% failed at one level, 18.2% failed at two, and none failed at three. For the ACDF failures, 76.1% failed at one level, 23.8% failed at two, and none failed at three. CONCLUSIONS: Three-level ACDF resulted in poor radiographic outcomes when assessed two years post-treatment. Including supplemental PCF not only increased the fusion rate at conclusion, but managed to achieve those successful outcomes much earlier.