What Cervical MRI Findings Can Tell About ACDF Outcomes and Risks of ASD

Study Design: A retrospective analysis of data on patients with cervical degenerative disc disease who underwent single-level anterior cervical discectomy and fusion (ACDF). Objective: To determine the association between preoperative cervical MRI parameters and surgical outcomes, and their role in the adjacent segment disease (ASD). Summary of Background Data: There is no evidence on what preoperative findings are related to ACDF outcomes, and the progression of postoperative degenerative changes at the adjacent levels has not been found yet. Methods: The patients’ demographic data, cervical MRI findings at all cervical levels and clinical data were collected preoperatively and postoperatively. A comparative analysis of MRIs of the levels adjacent and nondjacent to ACDF was performed to find out whether or not they were undergoing accelerated degeneration. A regression analysis was carried out for the identification of predictors of fusion rates and implant subsidence. Results: The study included 121 patients at visit 1 and 83 at visit 2. The median follow-up duration was 26.5 [18.9; 33.1] months. Complete fusions were observed in 85.5% of the patients (71/83), and implant subsidence was observed in 40% of the patients (33/83). Neither failed fusions nor implant subsidence were significant to clinical data ( P >0.05). Significant changes in the Modic changes ratio of type 1 to type 2 were observed 1 or 2 segments above ACDF ( P >0.05), along with an increase in the endplate damage there ( P <0.001). Endplate defects grade are a strong and independent predictor of implant subsidence at the same level (OR=1.3–12.94, P <0.05). Conclusions: At the levels adjacent to and above the ACDF segment, there is a change in the Modic change type-to-type ratio and an increase in the endplate damage. However, these changes in MRI parameters cannot be regarded as evidence for accelerated segment degeneration due to ACDF. Endplate defects revealed on preoperative MRI scans are predictors of implant subsidence at the same level.