Clinical and Radiographic Outcomes for Patients with Cervical Adjacent Segment Disease Treated with Anterior Cervical Discectomy and Fusion with Integrated Interbody Spacers

INTRODUCTION: Anterior cervical discectomy and fusion (ACDF) is among the most common spine procedres. Adjacent segment disease (ASD), characterized by degenerative disease at an adjacent spinal level to a prior fusion, is a well-recognized and significant sequela following ACDF. Adjacent segment ACDF may be considered after the failure of non-surgical options for patients with symptomatic ASD. This study aimed to assess the incidence of dysphagia and other complications as well as radiographic outcomes in adult patients who have under-gone ACDF with an integrated interbody spacer device for symptomatic ASD.METHODS: This was a retrospective review of patients who underwent ACDF for symptomatic ASD with commercially available integrated interbody spacers by three spine surgeons at an academic institution from March 2018 to April 2022. Demographic, radiographic, and postoperative data were collected, including dysphagia, device-related complications, and the need for revision surgery.RESULTS: There were 48 patients (26 male, 22 female) who met inclusion criteria (mean age 59.7 years, mean body mass index 19.5 kg/m2) who underwent ACDF for symptomatic ASD (1one-level, n = 44; 2-level, n = 4). Overall, 12 patients (25%) experienced dysphagia post-operatively before the first follow-up appointment. Nine of 44 (20.4%) of 1-level ACDF patients experienced dysphagia, and 3 of 4 (75%) of 2-level ACDF patients experienced dysphagia. Three patients had severe dysphagia which prompted an otolaryngology referral. Two of those patients remained symptomatic at 6 weeks postoperatively. Of 43 patients with prior plate cage systems, none required hardware removal at the time of surgery. Preoperative global and segmental lordosis were 9.07 degrees +/- 8.36 degrees (P = 0.22) and 3.58 degrees +/- 4.57 degrees (P = 0.14), respectively. At 6 weeks postoperatively, global and segmental lordosis were 11.44 degrees +/- 9.06 degrees (P = 0.54) and 5.11 degrees +/- 4.44 degrees (P = 0.44), respectively. This constitutes a change of +2.37 degrees and +1.53 degrees in global and segmental lordosis, respectively. The mean anterior disc height change between preoperative and immediate postoperative time points was 6.3 +/- 3.1 mm. Between the immediate postoperative and 6-week post -operative time points, the mean anterior disc height change was -1.5 +/- 2.7 mm. Between the immediate postoperative and 3-month postoperative time points, the mean anterior disc height change was -3.7 +/- 5.0 mm. The posterior disc height changes at the same time points were 2.5 +/- 1.7 mm, -0.4 +/- 1.8. and -0.5 +/- 1.4 mm, respectively. This fusion rate was 50% and 70% at 6 months and 1 year post-surgery, respectively.CONCLUSIONS: ACDF with integrated spacer is a viable alternative to traditional plate-cage systems for symptomatic ASD. An advantage over traditional plate-cage systems is that the removal of prior instrumentation is not needed in order to place implants. Based on a review of the literature, these standalone systems allowed for a shorter operative time and had less incidence of dysphagia than plate-cage systems for ASD after ACDF. The different standalone and dysphagia and reoperation), and radiographic outcomes such as global and segmental lordosis, subsidence, and fusion.