Liposomal Bupivacaine for Postoperative Analgesia After Multilevel Posterior Lumbar Fusion Surgery: A Prospective Three-Arm Randomized Study.

PURPOSE: This study compared three standardized postoperative analgesic strategies for adults undergoing multilevel posterior lumbar fusion surgery: liposomal bupivacaine thoracolumbar interfascial plane block (LB-TLIP), ropivacaine TLIP block (Ropi-TLIP), and liposomal bupivacaine local infiltration analgesia (LB-LIA).

PATIENTS AND

METHODS

This prospective, randomized, open-label, three-arm study enrolled 90 adults, with 30 patients in each group. The registry-listed primary outcome comprised serial resting and movement-evoked numerical rating scale (NRS) scores at 2, 6, 12, 24, 36, 48, and 72 hours after discharge from the operating room. These profiles were analyzed longitudinally using repeated-measures fixed-effects models with participant-level cluster-robust standard errors. The 2-72-hour NRS area under the curve (AUC) was calculated as a non-registered exploratory derived summary; it was used for pilot-based sample-size planning but was not separately listed in the registry or documented in a dated statistical analysis plan. The trial was prospectively registered in the Chinese Clinical Trial Registry (ChiCTR2500097484) on February 19, 2025.

RESULTS

Movement-evoked NRS profiles showed significant group and group-by-time effects (P<0.001 and P=0.001, respectively). Resting NRS profiles showed a significant group effect (P=0.003) without a significant group-by-time interaction (P=0.133). The LB-LIA group generally had the lowest early pain scores. Exploratory movement-evoked AUC values were 220.0 ± 28.4, 244.6 ± 30.6, and 257.1 ± 34.4 NRS·h for LB-LIA, LB-TLIP, and Ropi-TLIP, respectively (adjusted overall P<0.001). Time to first ambulation favored LB-LIA, whereas rescue tramadol use, hospital stay, and recorded adverse events did not differ significantly.

CONCLUSION

Serial NRS trajectories differed among groups, with generally lower early scores in the LB-LIA group. Exploratory AUC summaries were directionally consistent. These findings support lower early postoperative pain scores rather than broader clinical, mechanistic, opioid-sparing, or safety superiority.

TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2500097484; registered on February 19, 2025.