Degenerative Changes of Adjacent Segment Following Cervical Anterior fusion -Correlation with Preoperative MRI Findings of Adjacent Disc-

Abstract

Study Design: We retrospectively reviewed the preoperative and postoperative radiographs of patients who underwent anterior cervical discectomy and fusion. Objectives: We wanted to determine whether the preoperative Magnetic Resonance Imaging (MRI) findings of the levels adjacent to the level of fusion correlated with the postoperative degenerative changes seen on X-ray after anterior cervical discectomy and fusion. Summary of Literature Review: Anterior cervical fusion causes acceleration of the degenerative changes at the levels below or above the fused segment. These changes may be accelerated if preoperative MRI shows degenerative changes at the levels adjacent to the segment to be fused. Materials and Methods: Twenty-two patients (forty-four adjacent levels) who underwent anterior cervical discectomy and fusion from January 1998 to August 2002 (average follow up: 2 years and 6 months, range: 2 to 4 years) were enrolled in this study. Preoperatively, all the patients had no degenerative changes at adjacent levels on the plain radiographs, but they had at least one adjacent level with degenerative findings on MRI. The patients were grouped according to the findings of the adjacent levels seen on MRI: low signal changes on the T2 weighted image (group A), disc bulging on the sagittal and axial images (group B), annular tear seen on the axial image (group C), osteophyte formation (group D), and no abnormalities (group E). Results: Out of 44 cases of 22 patients, 14 cases (31.8%) showed degenerative changes. 2 out of 7 in group A, 6 out of 11 in group B, 3 out of 4 in group C, 2 out of 3 in group D and 1 out of 19 in group E showed degenerative changes on X-rays at the final follow up. Conclusion: Our findings suggest that abnormalities on the levels adjacent to the level to be fused, as seen on preoperative MRI, predispose these levels to degenerative changes postoperatively.