PURPOSE: The purpose of this study is to analyze the affecting factors of adjacent level ossification development (ALOD) after anterior cervical discectomy and fusion. MATERIALS AND METHODS: This study enrolled 75 patients who underwent anterior cervical discectomy and fusion and were followed-up for more than two years. Twenty-five patients were related with trauma and 47 patients were diagnosed as degenerative cervical disorder. We assessed the incidence, location and timing of ALOD, and compared the incidence of ossification between trauma and degenerative disease groups to know the effect of soft tissue damage. We also reviewed the correlation between the development of ossification at adjacent level and the factors, such as fusion level, age, operation time, duration of follow-up, and the presence of ossification of posterior longitudinal ligament (OPLL), as well as ossification of yellow ligament (OYL). RESULTS: Ossification developed in 33 patients (44%). Five cases (15%) were detected during the first year after surgery, 10 (30%) cases detected during the second year after surgery, 13 (40%) between second and third year, and 5 (15%) cases of more than three years after surgery. Only the fusion level was related with the development of ossification statistically (p<0.001). Age, operation time, duration of follow-up, sex ratio, presence of OPLL, and OYL were not related with the incidence of ossification significantly. There was no significant difference in the incidence of ALOD between the trauma group and degenerative disease group (p=0.3625). CONCLUSION: To detect ALOD, it needs a long time for follow-up after surgery. We thought that ALOD is affected by excessive loading at the adjacent level after fusion rather than severity of the soft tissue damage.
Cervical Vertebrae ; Diskectomy ; Female ; Follow-Up Studies ; Humans ; Incidence ; Ligaments ; Ossification of Posterior Longitudinal Ligament ; Sex Ratio