Published online Feb 22, 2011.
https://doi.org/10.4055/jkoa.2011.46.1.35
Significance of Mal-alignment after Anterior Cervical Arthrodesis in Degenerative Cervical Spinal Disorders
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±6.2° after surgery (p=0.002), but had recovered to 12.2±9.5° by the last Follow-up (p=0.859). In group B, cervical lordosis was improved from 9.6±10.5° to 22.5±9.7° (p=0.0003) after surgery and correction was maintained to 27.5±9.1° (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.
Figure 1
Measurement of the alignment of the entire cervical spine (angle A) and of the fused (angle B), unfused (angle C) segments. Angle A is the supplementary angle between the line parallel to the dorsal border of the C2 and the line parallel to that of the C7. Angle B is formed by the upper plane and the lower plane of the fused segment. Angle C is formed by the upper plane and the lower plane of the unfused segment.
Figure 2
This 27-year-old male patient with a cervical myelopathy and disc herniation at C5-6 underwent anterior cervical discectomy and fusion with a PEEK cage, and plate fixation. (A) Preoperative lateral radiograph shows degenerative disc space narrowing at C5-6. (B) Postoperative lateral radiograph shows the loss of cervical lordosis. (C) Lateral radiograph taken 1 year after surgery shows recovery of cervical lordosis and solid bony union.
Figure 3
This 47-year-old male patient with a cervical disc herniation at C5-6 underwent anterior cervical discectomy and fusion with a PEEK cage, and plate fixation. (A) Preoperative lateral radiograph shows global kyphosis. (B) Postoperative lateral radiograph shows the improvement of sagittal alignment. (C) Lateral radiograph taken 4 years after surgery shows further improvement of cervical lordosis and solid bony union.
Table 1
Patient Characteristics of Two Groups
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