Table 1.
Lumbar Spinal Stenosis (SPS) Operative treatments, complications and events*
| SPS | (BMI<30) (n=249) |
(30≤BMI<35) (n=103) |
(BMI≥35) (n=59) |
p-value |
|---|---|---|---|---|
| Specific procedures - no. (%)† | 0.72 | |||
| Decompression only | 215 (87%) | 91 (92%) | 50 (86%) | |
| Non-instrumented fusion | 15 (6%) | 4 (4%) | 3 (5%) | |
| Instrumented fusion | 16 (7%) | 4 (4%) | 5 (9%) | |
| Multi-level fusion -no. (%) | 10 (4%) | 5 (5%) | 1 (2%) | 0.60 |
| Decompression level - no. (%) | ||||
| L2–L3 | 78 (32%) | 46 (46%) | 23 (40%) | 0.05 |
| L3–L4 | 173 (71%) | 72 (71%) | 37 (64%) | 0.54 |
| L4–L5 | 225 (92%) | 94 (93%) | 54 (93%) | 0.95 |
| L5-S1 | 96 (39%) | 33 (33%) | 24 (41%) | 0.43 |
| Levels decompressed - no. (%) | 0.49 | |||
| None | 5 (2%) | 2 (2%) | 1 (2%) | |
| 1 | 54 (22%) | 27 (26%) | 12 (20%) | |
| 2 | 83 (33%) | 23 (22%) | 22 (37%) | |
| 3+ | 107 (43%) | 51 (50%) | 24 (41%) | |
| Operation time, minutes (SD) | 126.2 (66.5) | 127.8 (63.4) | 141.4 (66.7) | 0.28 |
| Blood loss, cc (SD) | 286.3 (327.4) | 354.4 (570.5) | 342.6 (345.7) | 0.30 |
| Blood Replacement - no. (%) | ||||
| Intraoperative replacement | 25 (10%) | 6 (6%) | 8 (14%) | 0.24 |
| Post-operative transfusion | 14 (6%) | 1 (1%) | 5 (9%) | 0.068 |
| Length of hospital stay, days (SD) | 3.3 (2.3) | 2.8 (1.7) | 3.6 (3.7) | 0.14 |
| Intraoperative complications - no. (%)§ | ||||
| Dural tear/ spinal fluid leak | 23 (9%) | 10 (10%) | 5 (8%) | 0.97 |
| Other | 3 (1%) | 0 (0%) | 0 (0%) | 0.37 |
| None | 221 (89%) | 93 (90%) | 54 (92%) | 0.89 |
| Postoperative complications/events - no. (%)¶ | ||||
| Wound hematoma | 3 (1%) | 1 (1%) | 0 (0%) | 0.70 |
| Wound infection | 6 (2%) | 1 (1%) | 2 (3%) | 0.55 |
| Other | 17 (7%) | 2 (2%) | 5 (9%) | 0.13 |
| None | 209 (85%) | 97 (95%) | 48 (83%) | 0.02 |
| Post-operative mortality (death within 6 weeks of surgery) - no. (%) | 1 (0.4%) | 0 (0%) | 0 (0%) | 0.72 |
| Post-operative mortality (death within 3 months of surgery) - no. (%) | 1 (0.4%) | 0 (0%) | 0 (0%) | 0.72 |
| Additional surgeries (1-year rate) - no. (%)‖ | 15 (6%) | 4 (4%) | 3 (5%) | 0.75 |
| Additional surgeries (2-year rate) - no. (%)‖ | 20 (8%) | 8 (8%) | 4 (7%) | 0.96 |
| Additional surgeries (3-year rate) - no. (%)‖ | 30 (12%) | 10 (10%) | 6 (10%) | 0.82 |
| Additional surgeries (4-year rate) - no. (%)‖ | 35 (14%) | 13 (13%) | 6 (10%) | 0.76 |
| Recurrent stenosis / progressive listhesis | 14 (6%) | 7 (7%) | 3 (5%) | |
| Pseudarthrosis / fusion exploration | 0 | 0 | 0 | |
| Complication or Other | 11 (4.5%) | 4 (3.9%) | 3 (5%) | |
| New condition | 4 (1.6%) | 4 (3.9%) | 0 |
Surgical information was available for 249 (BMI<30), 103 (30≤BMI<35), and 59 (BMI≥35) patients.
Specific procedure data was available for 246 (BMI<30), 99 (30≤BMI<35), and 58 (BMI335) patients.
No cases were reported of aspiration into the respiratory tract, vascular injury, nerve root injury, or operation at wrong level.
Complications or events occurring up to 8 weeks after surgery are listed. There were no reported cases of bone-graft complication, cerebrospinal fluid leak, paralysis, cauda equina injury, nerve root injury, wound dehiscence, or pseudarthrosis.
Rates of repeated surgery at 1, 2, 3, and 4 years are Kaplan-Meier estimates. P-values were calculated with the use of the log-rank test. Numbers and percentages are based on the first additional surgery if more than one additional surgery.