Table 3.
Improvement rate change based on parameter estimation in the mixed effect model
| Processing and level | Estimation | SE | DF | t | P value |
|---|---|---|---|---|---|
| Intercept | 9.7429 | 0.1452 | 120 | 67.09 | <0.0001 |
| Surgery | |||||
| Anterior approach | 4.1787 | 0.1202 | 120 | 34.75 | <0.0001 |
| Posterior approach | 0 | – | – | – | – |
| Canal stenosis | |||||
| Mild | 1.1532 | 0.2692 | 120 | 4.28 | <0.0001 |
| Moderate | 0.2891 | 0.1861 | 120 | 1.55 | 0.1230 |
| Severe | 0 | – | – | – | – |
| Cervical curvature | |||||
| Lordosis | 2.0542 | 0.2581 | 120 | 7.96 | <0.0001 |
| Straight | 1.1337 | 0.1730 | 120 | 6.55 | <0.0001 |
| Kyphosis | 0 | – | – | – | – |
| MRI signal | |||||
| No change | 0.4937 | 0.2418 | 120 | 2.04 | 0.0434 |
| High signal | 0 | – | – | – | – |
| Cervical curvature | |||||
| BS | −5.8179 | 0.1081 | 360 | −53.81 | <0.0001 |
| AS 1 week | −1.4426 | 0.09060 | 360 | −15.92 | <0.0001 |
| AS 1 year | −0.8470 | 0.06577 | 360 | −12.88 | <0.0001 |
| AS 5 years | 0 | – | – | – | – |
| Surgical approach × JOA scoring time | |||||
| Anterior × BS | −0.1209 | 0.08953 | 360 | −1.35 | 0.1778 |
| Anterior × AS 1 week | −0.3638 | 0.07502 | 360 | −4.85 | <0.0001 |
| Anterior × AS 1 year | 0.03992 | 0.05446 | 360 | 0.73 | 0.4640 |
| Anterior × AS 5 years | 0 | – | – | – | – |
| Canal stenosis × JOA scoring time | |||||
| Mild × BS | 0.09433 | 0.2005 | 360 | 0.47 | 0.6383 |
| Mild × AS1 week | −0.1725 | 0.1680 | 360 | −1.03 | 0.3050 |
| Mild × AS 1 year | −0.1917 | 0.1219 | 360 | −1.57 | 0.1168 |
| Mild × AS 5 years | 0 | – | – | – | – |
| Moderate × BS | 0.008118 | 0.1386 | 360 | 0.06 | 0.9533 |
| Moderate × AS 1 week | 0.05115 | 0.1161 | 360 | 0.44 | 0.6599 |
| Moderate × AS 1 year | −0.3037 | 0.08431 | 360 | −3.60 | 0.0004 |
| Moderate × AS 5 years | 0 | – | – | – | – |
| Cervical curvature × JOA scoring time | |||||
| Lordosis × BS | −0.06888 | 0.1922 | 360 | −0.36 | 0.7203 |
| Lordosis × AS 1 week | −0.09751 | 0.1610 | 360 | −0.61 | 0.5452 |
| Lordosis × AS 1 year | 0.4267 | 0.1169 | 360 | 3.65 | 0.0003 |
| Lordosis × AS 5 years | 0 | – | – | – | – |
| Straight × BS | −0.05900 | 0.1288 | 360 | −0.46 | 0.6473 |
| Straight × AS 1 week | −0.1619 | 0.1079 | 360 | −1.50 | 0.1346 |
| Straight × AS 1 year | 0.1167 | 0.07837 | 360 | 1.49 | 0.1373 |
| Straight × AS 5 years | 0 | – | – | – | – |
| MRI signal × JOA scoring time | |||||
| No change × BS | −0.4378 | 0.1800 | 360 | −2.43 | 0.0155 |
| No change × AS 1 week | −0.04684 | 0.1508 | 360 | −0.31 | 0.7564 |
| No change × AS 1 year | 0.2968 | 0.1095 | 360 | 2.71 | 0.0071 |
| No change × AS 5 years | 0 | – | – | – | – |
In the interactive effects view, the anterior approach after surgery 5 years, mild spinal stenosis × after 5 years, moderate occupying ratio of OPLL × after 5 years, cervical lordosis × after 5 years, straight cervical spine surgery × after 5 years, and no MRI signal change × after 5 years all represent baseline data. There was a significant difference between post-operative week 1 and 5 years in moderate occupying ratio of OPLL, cervical lordosis, and patients with no MRI signal change
BS before surgery, AS after surgery, JOA Japanese Orthopedic Association