Liposomal Bupivacaine Versus Continuous Peripheral Nerve Blocks for Analgesia Following Ankle Surgery

Postoperative pain remains undertreated. Opioids have well-known limitations for both individuals and society, and while single-injection peripheral nerve blocks with unencapsulated local anesthetic provide potent analgesia, their duration is measured in hours while post-surgical pain usually outlasts this duration. Continuous peripheral nerve blocks prolong analgesia but may possibly be replaced with liposomal bupivacaine with a reported duration of up to 72-96 hours (Schwartz. J Clin Anesth 2024). In comparison to continuous peripheral nerve blocks, liposomal bupivacaine eliminates a time-consuming catheter insertion as well as the risks of catheter dislodgement, localized infection, local anesthetic leakage, and infusion pump malfunction. Furthermore, liposomal bupivacaine significantly reduces the burden on both patients and healthcare providers as it does not require the use of a portable infusion pump, local anesthetic reservoir, or perineural catheter to be carried, managed, or eventually removed. Notably, the potential for local anesthetic-induced myotoxicity, and cardiac/neurologic toxicity is reduced or negated altogether. And the cost of liposome bupivacaine is less than the combined cost of a catheter set, insertion equipment, portable infusion pump, large reservoir of local anesthetic, and healthcare provider oversight. Therefore, should a single injection of liposomal bupivacaine be demonstrated to provide at least non-inferior analgesia and opioid sparing as a continuous peripheral nerve block, it would be a far superior analgesic benefiting patients, providers, hospitals, and payers such as Medicare and private health insurance. Randomized, active-controlled clinical trials are required to compare the newer liposomal bupivacaine to continuous peripheral nerve blocks. The ultimate objective of the proposed research study is to determine if liposomal bupivacaine in a peripheral nerve block is at least non-inferior to a continuous peripheral nerve block following moderate-to-severely painful ankle surgery. This is a single-center clinical trial. The investigators will randomize participants to either a liposomal bupivacaine combined with unencapsulated bupivacaine single-injection popliteal-sciatic and saphenous nerve block group, or single injections of unencapsulated bupivacaine followed by a continuous popliteal-sciatic bupivacaine infusion.

Inclusion Criteria: 1. Adult patients of at least 18 years of age 2. Undergoing a primary, unilateral, moderate-to-severely painful ankle surgery 3. Planned single-injection adductor canal nerve block and popliteal-sciatic catheter 4. Weight \> 50 kg (to minimize the risk of local anesthetic toxicity) Exclusion Criteria: 1. chronic opioid or tramadol use: daily oxycodone equivalents \> 20 mg for \> 4 weeks 2. neuro-muscular deficit of the surgical limb 3. moderate pain (NRS \> 3) in an anatomic location other than the surgical site 4. surgery outside the sciatic and saphenous nerve distributions 5. history of opioid misuse 6. inability to communicate with the investigators 7. inability to contact the investigators during the treatment period, and vice versa (e.g., lack of telephone access) 8. incarceration 9. pregnancy 10. allergy to amide local anesthetics or other study medication 11. active lower extremity infection or other contraindications to a peripheral nerve catheter