Table 2.
Dependence of the occurrence and degree of subsidence on selected radiological ratios. a—statistical analysis using Mann–Whitney test; b—statistical analysis using independent t-test; c—statistical analysis using Welch test; d—Kruskal–Wallis test; e—univariate ANOVA; 1—the ratio between the length of the cage and the length of the endplate (11.5/C in Figure 2); 2—the quotient obtained by dividing the ratio of cage length to endplate length by the distance of the cage from the middle column [(11.5/C)/F in Figure 2]; 3—the ratio was calculated by dividing the distance of the cage from the middle column by the length of the endplate (F/C in Figure 2); 4—the ratio between the height of the implant and the preoperative intervertebral space (implant height/D in Figure 2); 5—the ratio between the height of the implant and the preoperative segmental height (implant height/E in Figure 2); 6—the respective ratio between the implant height and the upper vertebral body height (implant height/A in Figure 2) and lower vertebral body height (implant height/B in Figure 2). Statistically significant results in bold.
| Subsidence | Subsidence Degree | |||||
|---|---|---|---|---|---|---|
| Yes | No | ≥2 and <3 [mm] | ≥3 and <4 [mm] | ≥4 [mm] | ||
| Number of disc spaces: (%) | 82 (52.2%) | 75 (47.8%) | 34 (41.5%) | 32 (39%) | 16 (19.5%) | |
| Parameters | ||||||
| Cage-to-endplate length ratio 1 | Mean: | 0.51 | 0.53 | 0.52 | 0.51 | 0.50 |
| Coefficient: | T = 1.79 b | H = 1.04 d | ||||
| p value | 0.0448 b | 0.5947 d | ||||
| Cage–endplate distance ratio 2 | Mean: | 0.22 | 0.17 | 0.29 | 0.18 | 0.15 |
| Coefficient: | Z = 1.53 a | H = 2.79 d | ||||
| p value | 0.1273 a | 0.2477 d | ||||
| Cage distance to endplate length ratio 3 | Mean: | 0.20 | 0.19 | 0.22 | 0.19 | 0.17 |
| Coefficient: | Z = −0.92 a | H = 2.24 d | ||||
| p value | 0.3602 a | 0.3255 d | ||||
| Cage-to-preoperative intervertebral space height ratio 4 | Mean: | 1.18 | 1.1 | 1.1 | 1.16 | 1.3 |
| Coefficient: | Z = 2.14 a | H = 4.69 d | ||||
| p value | 0.0367 a | 0.0447 d | ||||
| Cage-to-preoperative segmental height ratio 5 | Mean: | 0.18 | 0.16 | 0.16 | 0.18 | 0.2 |
| Coefficient: | −1.53 c | F = 2.54 e | ||||
| p value | 0.0322 c | 0.0389 e | ||||
| Cage to upper vertebral body height ratio 6 | Mean: | 0.41 | 0.40 | 0.41 | 0.42 | 0.40 |
| Coefficient: | T = −0.54 b | F = 0.32 e | ||||
| p value | 0.5893 b | 0.7237 e | ||||
| Cage-to-lower vertebral body height ratio 6 | Mean: | 0.40 | 0.40 | 0.40 | 0.41 | 0.37 |
| Coefficient: | Z = 0.27 | F = 2.27 e | ||||
| p value | 0.7855 a | 0.1100 e | ||||