Study design: A randomized, double-blinded controlled trial.

Objective: This study tested the effect of single-dose wound infiltration with multiple drugs for pain management after lumbar spine surgery.

Summary of background data: Patients undergoing spine surgery often experience severe pain especially in early postoperative period. We hypothesized that intraoperative wound infiltration with multiple drugs would improve outcomes in lumbar spine surgery.

Methods: Fifty-two patients who underwent one to two levels of spinous process splitting laminectomy of lumbar spine, were randomized into two groups. Infiltration group received intraoperative wound infiltration of local anesthetics, morphine sulfate, epinephrine, and nonsteroidal anti-inflammatory drugs at the end of surgery, and received patient-controlled analgesia (PCA) postoperatively. The control group received only PCA postoperatively. The primary outcome measures were amount of morphine consumption and visual analogue scale (VAS) for pain. The secondary outcome measures were Oswestry Disability Index (ODI), Roland-Morris Low Back Pain and Disability Questionnaire (RMDQ), patient satisfaction, length of hospital stay, and side effects.

Results: A total of 49 patients (23 patients for local infiltration group, and 26 patients for control group) were analyzed. There were statistically significant [P < 0.001, the effect size -5.0, 95% CI (-6.1, -3.9)] less morphine consumptions in the local infiltration group than the control group during the first 12 hours, 12 to 24 hours, and 24 to 48 hours after surgery. The VAS of postoperative pain reported by patients at rest and during motion was significantly lower in the local infiltration group than the control group at all assessment times (P < 0.001). The effect size of VAS of postoperative pain at rest and during motion were -2.0, 95% CI (-2.5, -1.4) and -2.0, 95% CI (-2.6, -1.4) respectively. ODI and RMDQ at 2 week and 3 month follow-ups in both groups had significant improvement from baseline (P < 0.001). No significant differences were found between groups (P = 0.262 for ODI and P = 0.296 for RMDQ). There were no significant differences of patient satisfaction, length of stay, and side effects between both groups (P = 0.256, P = 0.262, P = 0.145 respectively).

Conclusion: Intraoperative wound infiltration with multimodal drugs reduced postoperative morphine consumption, decreased pain score with no increased side effects.