Introduction
Materials and methods
Patient data
Formula deduction
Parametric measurements
Validation of the formula describing the relationship between the laminoplasty opening angle and the increase in sagittal diameter
Prediction of the amount of canal enlargement
Statistical analysis
Results
Data for C3–C7 parameters
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Preoperative lamina angle (α): The largest preoperative lamina angles (α) were seen at C3 (31.15 ± 2.21) and C7 (32.61 ± 2.29). C5 and C6 had α value of 29.49 ± 2.62 and 29.20 ± 2.75, respectively. C4 had the smallest α value at 28.53 ± 2.82 (Table 1).Table 1Parameters used in the studyParameterC3C4C5C6C7Preoperative lamina angle (α)31.15 ± 2.2128.53 ± 2.8229.49 ± 2.6229.20 ± 2.7532.61 ± 2.29LOA (γ)43.55 ± 7.9044.13 ± 7.6145.43 ± 7.2543.41 ± 7.9944.64 ± 6.63Distance between points E and F (mm)18.36 ± 1.3018.51 ± 1.5318.64 ± 1.5018.41 ± 1.1616.84 ± 1.07Distance between points A and B (mm)5.55 ± 0.545.03 ± 0.625.27 ± 0.625.16 ± 0.625.39 ± 0.50Preoperative SCD (mm)11.82 ± 1.0411.17 ± 1.1411.44 ± 1.1011.61 ± 1.0912.11 ± 1.01Postoperative SCD (mm)18.19 ± 2.0317.98 ± 2.2718.49 ± 2.1318.18 ± 2.0517.96 ± 1.61
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Distance between points E and F: The largest E to F distances were seen at C3, C4, C5, and C6 (18.36 ± 1.30, 18.51 ± 1.53, 18.64 ± 1.50, and 18.41 ± 1.16, respectively). The smallest distance was at C7 (16.84 ± 1.07) (Table 1).
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Distance between points A and B (h value): The largest distance from A to B was at C3 (5.55 ± 0.54). Smaller distances were seen at C4, C5, C6, and C7 (5.03 ± 0.62, 5.27 ± 0.62, 5.16 ± 0.62, and 5.39 ± 0.50, respectively) (Table 1).
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Preoperative SCD (AO): Smaller preoperative SCDs (AO) were seen at C4, C5, and C6 (11.17 ± 1.14, 11.44 ± 1.10, and 11.61 ± 1.09, respectively). Larger preoperative SCDs (AO) were seen at C3 and C7 (11.82 ± 1.04 and 12.11 ± 1.01, respectively) (Table 1).
Differences and correlation between the data obtained by clinical measurement and the data predicted by the formula relating LOA to the increase in SCD
Parameter | C3 | C4 | C5 | C6 | C7 |
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SCD increase obtained by formula (mm) | 6.37 ± 1.74 | 6.81 ± 1.85 | 7.05 ± 1.89 | 6.57 ± 1.82 | 5.85 ± 1.30 |
SCD increase obtained by measuring (mm) | 6.43 ± 1.63 | 6.76 ± 1.82 | 7.01 ± 1.90 | 6.53 ± 1.79 | 5.81 ± 1.26 |
t value | 1.43 | 1.38 | 1.43 | 1.26 | 1.11 |
P value | 0.1614 | 0.1773 | 0.1621 | 0.2144 | 0.2755 |
r value | 0.9905 | 0.9931 | 0.9953 | 0.9937 | 0.9886 |
P value | <0.0001 | <0.0001 | <0.0001 | <0.0001 | <0.0001 |
Spinal canal expansion following ODCL with opening sizes from 8 to 16 mm
LOS (mm) | Increase in SCD at C3 (mm) | Increase in SCD at C4 (mm) | Increase in SCD at C5 (mm) | Increase in SCD at C6 (mm) | Increase in SCD at C7 (mm) |
---|---|---|---|---|---|
8 | 3.09 ± 0.09 | 3.19 ± 0.11 | 3.15 ± 0.11 | 3.17 ± 0.11 | 3.08 ± 0.10 |
10 | 4.08 ± 0.14 | 4.22 ± 0.16 | 4.16 ± 0.16 | 4.18 ± 0.16 | 4.09 ± 0.15 |
12 | 5.20 ± 0.20 | 5.39 ± 0.23 | 5.31 ± 0.23 | 5.35 ± 0.23 | 5.27 ± 0.22 |
14 | 6.52 ± 0.30 | 6.77 ± 0.36 | 6.65 ± 0.35 | 6.71 ± 0.33 | 6.67 ± 0.34 |
16 | 8.09 ± 0.45 | 8.44 ± 0.56 | 8.26 ± 0.54 | 8.35 ± 0.50 | – |
LOS (mm) | LOA at C3 (°) | LOA at C4 (°) | LOA at C5 (°) | LOA at C6 (°) | LOA at C7 (°) |
---|---|---|---|---|---|
8 | 25.30 ± 1.83 | 25.14 ± 2.18 | 24.95 ± 2.05 | 25.19 ± 1.61 | 27.59 ± 1.79 |
10 | 31.77 ± 2.33 | 31.57 ± 2.77 | 31.33 ± 2.60 | 31.64 ± 2.05 | 34.68 ± 2.28 |
12 | 38.36 ± 2.84 | 38.11 ± 3.39 | 37.82 ± 3.18 | 38.20 ± 2.50 | 41.92 ± 2.80 |
14 | 45.08 ± 3.40 | 44.79 ± 4.04 | 44.44 ± 3.79 | 44.88 ± 2.98 | 49.34 ± 3.36 |
16 | 51.97 ± 3.99 | 51.64 ± 4.75 | 51.22 ± 4.45 | 51.74 ± 3.51 | – |
LOS (mm) | Increases in canal area at C3 (mm2) | Increases in canal area at C4 (mm2) | Increases in canal area at C5 (mm2) | Increases in canal area at C6 (mm2) | Increases in canal area at C7 (mm2) |
---|---|---|---|---|---|
8 | 71.66 ± 5.31 | 72.28 ± 6.28 | 72.81 ± 6.13 | 71.89 ± 4.77 | 65.44 ± 4.41 |
10 | 88.30 ± 6.74 | 89.09 ± 7.80 | 89.76 ± 7.78 | 88.60 ± 6.05 | 80.41 ± 5.61 |
12 | 104.07 ± 8.23 | 105.02 ± 9.74 | 105.84 ± 9.50 | 104.43 ± 7.39 | 94.40 ± 6.88 |
14 | 118.74 ± 9.82 | 119.87 ± 11.62 | 120.85 ± 11.32 | 119.17 ± 8.81 | 107.19 ± 8.25 |
16 | 132.09 ± 11.54 | 133.41 ± 13.65 | 134.56 ± 13.28 | 132.61 ± 10.34 | – |