Patient demographic and perioperative characteristics.
| Characteristic | Expandable Cage (n = 48) | Static Cage (n = 50) | P Value |
| Patient Demographics | |||
| Age, y, mean (range, SD) | 71.2 (43–84, 8.5) | 67.2 (27–89, 13.2) | 0.143 |
| Sex, n (%) | 0.838 | ||
| Men | 21 (43.8) | 25 (50.0) | |
| Women | 27 (56.2) | 25 (50.0) | |
| Body mass index, mean (range, SD) | 28.7 (18–39, 4.3) | 28.5 (18–46, 5.5) | 0.567 |
| Current smoker, n (%) | 0.618 | ||
| Yes | 0 | 3 (6.0) | |
| No | 45 (93.8) | 44 (88.0) | |
| Unknown | 3 (6.2) | 3 (6.0) | |
| Operative Characteristics | |||
| Operated spinal segments n (%) | >0.999 | ||
| Single level | 35 (52.0) | 34 (56.0) | |
| 2 Levels | 10 (36.0) | 12 (28.0) | |
| 3 Levels or more | 3 (12.0) | 4 (16.0) | |
| Treated lumbar segments, n (%) | 0.308 | ||
| L1-L2 | 7 (9.3) | 5 (7.3) | |
| L2-L3 | 18 (27.9) | 15 (24.4) | |
| L3-L4 | 28 (41.9) | 22 (34.1) | |
| L4-L5 | 13 (20.9) | 27 (34.1) | |
| Radiographic Parameters | |||
| Preoperative disc height, mm, mean (range, SD) | |||
| Anterior | 6.0 (1–11.5, 2.5) | 6.4 (1–19.2, 3.4) | 0.251 |
| Posterior | 3.4 (1–5.9, 1.1) | 3.3 (1–7.0, 1.5) | 0.834 |
| Postoperative disc height, mm, mean (range, SD) | |||
| Anterior a | 10.0 (6.8–14.0, 1.8) | 9.4 (8–12, 2.3) | 0.004 |
| Posterior | 5.8 (3–8.5, 1.1) | 5.3 (1.1–9.2, 1.4) | 0.121 |
| % Increase in disc height postoperative, mean (range, SD) | |||
| Anterior disc height | 242.8 (99–1180, 178.6) | 238.9 (69.5–1130, 230.8) | 0.114 |
| Posterior disc height | 193.5 (89.7–541.7, 91.06) | 203.6 (56.9–650, 140.4) | 0.266 |
| Postoperative change in segmental lordosis degrees, mean (range, SD) | 3.6 (−3.6 to 19.2, 4.2) | 3.3 (−8.4 to 14.6, 4.2) | 0.947 |
↵a Refers to expanded final height in the expandable cage group, whereas static cages were of 8, 10, or 12 mm in height. Total levels decompressed for the expandable group: 84; for the static group: 85.