TABLE II.
Operative Treatments, Complications, and Events
| L2-L3 and L3-L4 (N = 42) | L4-L5 (N = 299) | L5-S1 (N = 432) | P Value* | |
|---|---|---|---|---|
| Operation time†(min) | 81.7 ± 36.2 | 82 ± 40.2 | 71.4 ± 32.1 | <0.001 |
| Blood loss†(mL) | 78.7 ± 76.1 | 72.6 ± 113.1 | 56 ± 90.9 | 0.053 |
| Intraoperative complications‡(no. of patients) | ||||
| Dural tear and/or spinal fluid leak | 1 (2%) | 12 (4%) | 10 (2%) | 0.40 |
| Nerve root injury | 0 (0%) | 1 (0%) | 0 (0%) | 0.45 |
| Vascular injury | 0 (0%) | 0 (0%) | 1 (0%) | 0.68 |
| Other | 0 (0%) | 1 (0%) | 2 (0%) | 0.89 |
| None | 40 (98%) | 285 (96%) | 419 (97%) | 0.58 |
| Postoperative complications or events§(no. of patients) | ||||
| Nerve root injury | 0 (0%) | 0 (0%) | 1 (0%) | 0.68 |
| Wound hematoma | 1 (2%) | 2 (1%) | 1 (0%) | 0.15 |
| Superficial wound infection | 1 (2%) | 3 (1%) | 9 (2%) | 0.51 |
| Deep wound infection | 0 (0%) | 2 (1%) | 3 (1%) | 0.87 |
| Other | 3 (7%) | 7 (2%) | 17 (4%) | 0.21 |
| None | 37 (90%) | 282 (96%) | 401 (93%) | 0.23 |
*
The p value is for the comparison across all three groups with use of analysis of variance for continuous variables and chi-square tests for categorical variables.
†
The values are given as the mean and the standard deviation.
‡
Data were not available for one patient with upper level herniation and for three patients with L4-L5 herniation. No instances of aspiration or operation at the wrong level were reported.
§
Any reported complications up to eight weeks postoperatively. No instances of blood transfusion, cerebrospinal fluid leak, paralysis, cauda equina injury, or wound dehiscence were reported.