Efficacy of N-Methyl-2Pyrolidone-Ethyl hepta-noate (PLGA)-bupivacaine in situ forming system on radicular and low back pain relief following lumbar discectomy: A randomized clinical trial

Lumbar disc herniation (LDH) is the most common surgical intervention of spine surgery. During few days of the operation, most patients experience worrying low back pain (LBP) and radicular leg pain (RLP). Applying liquid form of bupivacaine in the vicinity of surgical field could be effective on pain relief only for few hours after operation. In a double-blind prospective randomized clinical trial on patients with single level lumbar disc herniation (LDH), we tried to show the efficacy of N-Methyl-2Pyrolidone-Ethyl heptanoate (PLGA)-bupivacaine on LBP and RLP of 38 patients with American Society of Anesthesiologists (ASA) physical status I, and aged 27-65 years old.At the end of operation, 1 cc of PLGA-bupivacaine or pure PLGA was inoculated at the vicinity of thecal sac and root. LBP and RLP were measured using McGill Pain Questionnaire and visual analogue scale (VAS), immediately after operation and then after 6, 12 and 24 hours as well as one week and one month. The mean pain severity of LBP in PLGA-bupivacaine group (A) and pure PLGA group (B) were 25.7±2.8 and 30.6±5.8 (p<0.001), one week after surgery and 23.1±1.4 and 25.2±2 (p0.002), after two weeks, respectively. After 4 weeks of operation, the severity of LBP were 22.3±1.6 and 22.9±1 in two groups respectively (p=0.01). Severity of RLP according to VAS, from preoperative intervention until one month later, did not show any significant differences between two groups before and up to the first week after operation. However, after the first week until the end of follow-up, group A showed better scores in VAS. Accordingly, application of bupivacaine-PLGA had significant effect on LBP especially two weeks after operation, but it did not have any additional positive effects on RLP.