Subsidence Ratio after Anterior Cervical Interbody Fusion Using an Intraoperative Custom-made Cervical Cage

ABSTRACT

OBJECTIVE: The postoperative subsidence of anterior cervical interbody fusion for cervical degenerative diseases gives rise to segmental kyphotic collapse, screw loosening, and chronic neck pain. So, intraoperative custom-made polymethylmethacrylate (PMMA) C-cage has been developed to prevent subsidence following anterior cervical fusion. METHODS: A total of patients who underwent anterior cervical interbody fusion with a intraoperative custom - made cervical cage filled with local bone and demineralized bone matrix (group A) were analyzed prospectively from June 2004 to June 2005. These were compared with 40 patients who were treated with iliac bone graft (group B). We evaluated subsidence ratio, change of segmental angle, distraction length and segmental angle. Statistical analysis was performed using independent sample t-test and Pearson correlation coefficient. RESULTS: Group A had a statistically significant decrease in subsidence ratio (0.64+/-0.43%, p=0.00), distraction length (2.42+/-1.25 mm, p=0.02), and follow angle change (1.78+/-1.69degrees, p=0.01) as compared with Group B. However, there was no statistically significant difference in postoperative segmental angle change (p=0.66). On the analysis of the correlation coefficient, the parameters showed no interrelationships in the group A. On the other hand, subsidence ratio was affected by distraction length in the group B (Pearson correlation=0.448). CONCLUSION: This operative technique would be contributed for the reduction of a postoperative subsidence after the anterior cervical interbody fusion procedure for cervical disc disease with moderate to severe osteoporotic condition and segmental loss of lordosis.