Table 1.
Features between two groups before and after matching.
| Before propensity score matching | After propensity score matching | |||||
|---|---|---|---|---|---|---|
| T2WIHS (N = 326) | Normal (N = 587) | P | T2WIHS (N = 312) | Normal (N = 312) | P | |
| Gender | 0.002∗∗ | 0.645 | ||||
| Male | 226 (69.3) | 256 (43.6) | 212 (67.9) | 217 (69.6) | ||
| Female | 100 (30.7) | 331 (56.4) | 100 (32.1) | 95 (30.4) | ||
| Age | 0.126 | 0.090 | ||||
| 60 y | 209 (64.1) | 416 (70.9) | 201 (64.4) | 219 (70.2) | ||
| 60 y | 117 (35.9) | 171 (29.1) | 111 (35.6) | 93 (29.8) | ||
| BMI (kg/m2) | 0.145 | 0.252 | ||||
| 18.5 | 25 (7.7) | 26 (4.4) | 24 (7.7) | 16 (5.1) | ||
| 18.5~24.9 | 218 (66.9) | 403 (68.7) | 207 (66.3) | 210 (67.3) | ||
| 25.0 | 83 (25.4) | 158 (26.9) | 81 (26.0) | 86 (27.6) | ||
| Emergency admission | 0.459 | 0.905 | ||||
| Yes | 2 (0.6) | 5 (0.9) | 2 (0.6) | 4 (1.3) | ||
| No | 324 (99.4) | 582 (99.1) | 310 (99.4) | 308 (98.7) | ||
| Frankel grading | <0.001∗∗∗ | 0.536 | ||||
| C | 179 (54.9) | 199 (33.9) | 165 (52.9) | 166 (53.2) | ||
| D | 147 (45.1) | 388 (66.1) | 147 (47.1) | 146 (46.8) | ||
| Revision surgery | 0.880 | 0.832 | ||||
| Yes | 23 (7.1) | 30 (5.1) | 19 (6.1) | 25 (8.0) | ||
| No | 303 (92.9) | 557 (94.9) | 293 (93.9) | 287 (92.0) | ||
| OALL | 28 (8.6) | 54 (9.2) | 0.397 | 25 (8.0) | 30 (9.6) | 0.503 |
| OPLL | 63 (19.3) | 95 (16.2) | 0.250 | 56 (17.9) | 51 (16.3) | 0.256 |
| Cervical instability | 56 (17.2) | 56 (9.5) | 0.005∗∗ | 42 (13.5) | 36 (11.5) | 0.260 |
| Diabetes | 24 (7.4) | 43 (7.3) | 0.637 | 23 (7.4) | 26 (8.3) | 0.819 |
| Hypertension | 68 (20.9) | 99 (16.9) | 0.202 | 61 (19.6) | 55 (17.6) | 0.207 |
| Coronary heart disease | 2 (0.6) | 6 (1.0) | 0.397 | 2 (0.6) | 6 (1.9) | 0.145 |
| Liver and kidney dysfunction | 1 (0.3) | 3 (0.5) | 0.603 | 0 (0.0) | 1 (0.3) | 0.473 |
| Cerebrovascular disease | 6 (1.8) | 20 (3.4) | 0.270 | 6 (1.9) | 12 (3.8) | 0.492 |
| History of malignant tumor | 1 (0.3) | 4 (0.7) | 0.988 | 1 (0.3) | 0 (0.0) | 0.855 |
| Osteoporosis | 18 (5.5) | 37 (6.3) | 0.891 | 16 (5.1) | 15 (4.8) | 0.609 |
| Ankylosing spondylitis | 1 (0.3) | 2 (0.3) | 0.967 | 1 (0.3) | 1 (0.3) | 0.589 |
| Rheumatoid arthritis | 3 (0.9) | 9 (1.5) | 0.265 | 3 (1.0) | 6 (1.9) | 0.312 |
| Smoking history | 58 (17.8) | 80 (13.6) | 0.759 | 55 (17.6) | 49 (15.7) | 0.387 |
| Other infection | 0 (0.0) | 5 (0.9) | >0.99 | 0 (0.0) | 4 (1.3) | >0.99 |
| Operative approach | 0.958 | 0.935 | ||||
| Anterior | 257 (78.8) | 492 (83.8) | 249 (79.8) | 246 (78.8) | ||
| Posterior | 61 (18.7) | 84 (14.3) | 57 (18.3) | 58 (18.6) | ||
| Combined | 8 (2.5) | 11 (1.9) | 6 (1.9) | 8 (2.6) | ||
All data are shown as the mean ± SD and n (%) in the table. ∗P < 0.05, ∗∗P < 0.01, and ∗∗∗P < 0.001 displayed in the table. OALL: ossification of anterior longitudinal ligament; OPLL: ossification of posterior longitudinal ligament; BMI: body mass index; T2WIHS: T2-weighted image high signal.