Table 4.
Univariate Analysis of Delayed Cage Subsidence in Stand-alone Patients.
| Parameter | Groups | P value | |
|---|---|---|---|
| No Delayed Subsidence | Delayed Subsidence | ||
| No. of patients | 22 (68.8%) | 10 (31.2%) | |
| No. of levels | 30 (71.4%) | 12 (28.6%) | |
| Mean age (years) | 64.3 ± 12.7 | 67.8 ± 7.4 | .385 |
| Mean BMI (kg/m2) | 24.3 ± 2.9 | 24.7 ± 3.8 | .703 |
| Single-level cases | 16 (72.7%) | 4 (40.0%) | .168 |
| BMD (mg/cm3) a | 1.37 ± .26 | 1.26 ± 0.2 | .205 |
| Cage height (mm) | 15.2 ± 1.3 | 15.1 ± 1.7 | .919 |
| Cage length (mm) | 52.5 ± 3.2 | 54.4 ± 4.2 | .231 |
| Expected disc height restoration (mm) | 5.4 ± 2.3 | 5.0 ± 2.0 | .643 |
| Actual disc height restoration (mm) | 4.9 ± 1.9 | 5.1 ± 2.8 | .743 |
| VAS at 1-year follow-up | 2.3 ± .9 | 2.0 ± 0.6 | .136 |
| VAS improvement at 1-year follow-up | 2.8 ± 1.5 | 2.4 ± 1.0 | .173 |
| Upper endplate Hounsfield unit | |||
| Anterior epiphyseal ring | 489.9 ± 105.7 | 538.2 ± 115.3 | .200 |
| Posterior epiphyseal ring | 560.2 ± 123.5 | 524.0 ± 121.5 | .394 |
| Ipsilateral epiphyseal ring | 594.3 ± 108 | 565.1 ± 151.1 | .486 |
| Contralateral epiphyseal ring | 549.2 ± 108.4 | 517.4 ± 75.7 | .360 |
| Central endplate | 448.8 ± 103.8 | 406.8 ± 70.9 | .206 |
| Lower endplate Hounsfield unit | |||
| Anterior epiphyseal ring | 447.7 ± 116.4 | 436.2 ± 76.4 | .755 |
| Posterior epiphyseal ring | 480.6 ± 66.4 | 468.1 ± 81.0 | .607 |
| Ipsilateral epiphyseal ring | 506.1 ± 96.8 | 452.3 ± 88.2 | .104 |
| Contralateral epiphyseal ring | 520.0 ± 95.3 | 521.2 ± 134.3 | .974 |
| Central endplate | 401.2 ± 78.1 | 336.3 ± 55.8 | .013 |
BMI, body mass index; BMD, bone mineral density; VAS, visual analogue scale.
a36 patients (58 levels) underwent bone mineral density scanning preoperatively.