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Abstract
Objectives
To evaluate preoperative factors related with spinal canal expansion after posterior decompression for the treatment of multilevel cervical myelopathy.
Summary of Literature Review
Data about preoperative factors related with spinal canal expansion after posterior cervical decompression surgery are inconsistent.
Materials and Methods
We reviewed 67 patients with cervical myelopathy who underwent posterior laminectomy or laminoplasty. Radiologically, we evaluated the C2-7 Cobb angle and range of motion using X-rays from the preoperative assessment and final follow-up. Expansion of the spinal canal at 6 weeks postoperatively was evaluated using magnetic resonance imaging and compared with the preoperative values. The preoperative factors of age, sex, number of operated levels, operation method, and radiological parameters were investigated as factors potentially related to postoperative spinal canal expansion using multivariate regression and correlation analyses. The clinical outcome was analyzed by the Neck Disability Index (NDI) and Japanese Orthopaedic Association (JOA) scores.
Results
The postoperative spinal canal expansion was 4.76 mm in sagittal images and 4.31 mm in axial images, with higher values observed in males and cases of severe preoperative cord compression. A lordotic preoperative Cobb angle was related to postoperative spinal canal expansion and JOA score improvement, but without statistical significance. The clinical outcomes of NDI (18.3→14.8) and JOA scores (10.81→14.6) showed improvement, but were not significantly related with any preoperative factors.
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Fig. 2.
Severity of cord compression at the site of maximum compression was analyzed using T2-weighted sagittal and axial views on magnetic resonance imaging.(A) Sagittal occupy ratio was measured as B/A. (B) Axial occupy ratio was measured as B/A. (C, D) At the 6-week postoperative follow-up, the degree of spinal cord expansion was compared and analyzed with that prior to surgery as B-A.
Table 1.
Effect of demographic and radiological factors on postoperative increase of sagittal diameter (Multivariate regression analysis)
| β∗ | p-value† | |
|---|---|---|
| Age | −0.016 | 0.896 |
| Sex | −0.332 | 0.004 |
| Number of fused vertebra | 0.188 | 0.401 |
| Preoperative Cobb angle | 0.103 | 0.397 |
| Preoperative range of motion | 0.034 | 0.792 |
| Preoperative sagittal diameter | −0.530 | 0.000 |
| Preoperative axial diameter | −0.190 | 0.039 |
| Sagittal occupying ratio | −0.214 | 0.166 |
| Axial occupying ratio | −0.237 | 0.126 |
| Operation method | −0.413 | 0.075 |
Table 2.
Effect of demographic and radiological factors on postoperative increase of axial diameter (Multivariate regression analysis)
| β∗ | p-value† | |
|---|---|---|
| Age | 0.250 | 0.090 |
| Sex | −0.276 | 0.041 |
| number of fused vertebra | 0.005 | 0.985 |
| Preoperative Cobb angle | 0.024 | 0.870 |
| Preoperative range of motion | 0.029 | 0.851 |
| Preoperative sagittal diameter | −0.239 | 0.019 |
| Preoperative axial diameter | −0.297 | 0.027 |
| Sagittal occupying ratio | 0.068 | 0.709 |
| Axial occupying ratio | −0.336 | 0.070 |
| Operation method | −0.118 | 0.662 |
Table 3.
Radiological and clinical analysis according to preoperative Cobb angle (Chi square, t-test)
Table 4.
Correlation analysis between clinical outcomes and radiologica factors.
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