Liposomal Bupivacaine for Pain After Lumbar Fusion

"Patients will receive a pre-closure local infiltration of 266 mg liposomal bupivacaine (20 mL for single-level surgery; 30 mL for two-level surgery) combined with 25 mg bupivacaine hydrochloride (10 mL total volume). The drug will be injected bilateral into the paraspinal muscles and subcutaneous tissues prior to wound closure. This provides both immediate (bupivacaine HCl) and prolonged (liposomal) analgesia."

Patients will receive 120 mg ropivacaine diluted to 30 mL (single-level) or 40 mL (two-level) with normal saline. The solution will be infiltrated bilateral into the paraspinal muscles and subcutaneous tissues using the same technique as the experimental arm, ensuring consistent injection depth and distribution.