ABSTRACT
PURPOSE: The purpose of this study was to analyze the risk factors for postoperative sagittal mal-alignment after anterior cervical arthrodesis resulting from degenerative cervical disorders and its effect on radiological and clinical results. MATERIALS AND METHODS: We evaluated 50 patients who underwent anterior cervical arthrodesis for degenerative cervical disorder retrospectively. We assigned 25 patients who had sagittal mal-alignment after surgery to group A and 25 patients who had improvement of lordosis after surgery to group B. We evaluated the change of cervical lordosis, lordosis at fused segments, and lordosis at unfused segments. In addition, we evaluated radiological and clinical results. RESULTS: In group A, postoperative cervical lordosis worsened from 12.7+/-10.6 to 3.6+/-6.2degrees after surgery (p=0.002), but had recovered to 12.2+/-9.5degrees by the last Follow-up (p=0.859). In group B, cervical lordosis was improved from 9.6+/-10.5degrees to 22.5+/-9.7degrees (p=0.0003) after surgery and correction was maintained to 27.5+/-9.1degrees (p=0.0988) at the last follow up. Lordosis at fused segments were improved in both groups (p=0.001, 0.0001) but lordosis at unfused segments worsend in group A (p=0.0001). The factor associated with postoperative mal-alignment was symtoms of myelopathy (p=0.0436). Age, sex, fusion level, size of cage, and duration of symptoms were not significantly associated with postoperative changes in alignment. One nonunion occurred only in group A. Six cases of cage subsidences were found in group A, 3 cases in group B (p=0.4506). Adjacent segment degeneration was found in 8 segments in group A, 1 segment in group B (p=0.0048). The differences in clinical improvement evaluated by VAS, NDI between groups were not significant (p=0.88, p=0.91). CONCLUSION: Postoperative sagittal malalignment was a temporary and reversible change, and was not related to clinical results. However, it might be a factor in the increased incidence of adjacent segment degeneration.