Modic Changes in Patients Who Have Undergone Anterior Cervical Discectomy and Fusion: The Correlation With Fusion Success and Subsidence.

Abstract

Objective: There is a lack of research on modic change (MC) in the cervical spine, especially regarding its impact on patients following anterior cervical discectomy and fusion (ACDF). Some researchers strongly believe that MC may affect the prognosis after anterior cervical surgery. Thus, this study aimed to assess MC in patients who underwent ACDF, investigating its incidence, risk factors, and correlation with fusion success and subsidence rate.

Methods: We retrospectively reviewed 154 patients who underwent single-level ACDF from January 2010 to December 2020, with a minimum follow-up of 12 months. Preoperative and postoperative clinical and radiological parameters were recorded at pre-operation, 1 week, 3 months after operation, and the last follow-up. The primary outcomes were the fusion rate and cage subsidence. Radiological measurements, including overall (Cobb C) and segmental cervical angle (Cobb S), anterior disc height (ADH), and posterior disc height (PDH) were also recorded. The independent t-test or Mann-Whiteny U test was used to compare continuous data, and categorical variables were assessed using the Pearson's chi-square test of Fisher's exact test. Logistic regression analysis was also adopted to distinguish corresponding factors related with the progress of MC.

Results: Of the 154 patients, the incidence of MC was 44.2% (68/154). The group with MC showed a larger proportion of males and osteoporosis. The fusion rate of those with MC was 88.2% (60/68) while that in the non-MC group was 97.7% (84/86, p = 0.02). The MC group presented a subsidence rate of 27.9%, which was substantially higher than in the non-MC group (9.3%, p < 0.01). NDI and VAS neck was significantly higher in the MC group than in the non-MC group (p = 0.014; p = 0.039). Sex and osteoporosis were distinguished as independent factors related to MC by regression analysis (p = 0.006; p = 0.026).

Conclusion: Preoperative MC could adversely hinder the fusion process and may increase the incidence of subsidence, affecting clinical outcomes of those underwent ACDF. Patients with MC, especially type 1 MC, are more easily suffered from neck pain than those without MC. Male sex and osteoporosis were risk factors for MC. In order to achieve a better bony fusion and avoid cage subsidence in those with MC, we encourage patients to prolong their immobilization duration with a cervical collar and precisely manage osteoporosis during the peri-operative period.