Comparison of Liposomal Bupivacaine Versus Ropivacaine in Alleviating Rebound Pain

Shoulder arthroscopy is a frequently performed orthopedic procedure used to address various issues like rotator cuff tears, instability, and stiffness. However，postoperative pain is a common complaint, effective postoperative pain management is a crucial component to recovery after shoulder arthroscopy. For pain control after arthroscopic shoulder surgery, the interscalene brachial plexus block (IBP) is often regarded as the gold standard. It is easy to perform and has limited side effects. Nonetheless, the pain-relieving effects of the block usually last for less than 24 hours, even when using long-lasting local anesthetics like bupivacaine and ropivacaine. Considerable rebound pain is an important limitations of nerve block against postoperative pain.Its incidence is reported to be between 35% and 62% , and is more common after bone and joint surgeries, especially those involving the shoulder and knee, with a frequency 1.8 times greater than that of soft tissue operations . Therefore, it is essential to establish effective measures to avert its occurrence.Liposomal bupivacaine with its multivesicular formulation, is designed to facilitate the sustained and controlled release of bupivacaine. This formulation extended the duration of anesthetic effect and minimized rebound pain. However, studies on liposomal bupivacaine for peripheral nerve blockade have engendered great controversy. Numerous researches suggested that the use of liposomal bupivacaine for shoulder surgeries is comparable to conventional local anesthetics in terms of overall pain relief, opioids consumption, hospital stays, and postoperative complications. In this study, a randomized controlled trial with blinding of patients and outcome assessors was conducted to determine whether liposomal bupivacaine in the interscalene brachial plexus block would improve rebound pain compared to ropivacaine in patients undergoing arthroscopic shoulder surgery.

Inclusion Criteria: * adults between 18 and 65 year-old * American Society of Anesthesiologist (ASA) grades 1 to 3 physical classification status * patients unilateral primary arthroscopic shoulder surgery lasting 1to 4 hours Exclusion Criteria: * had an allergy or intolerance to amide-type local anesthetics * objective evidence of nerve damage in the affected upper limb * local infection * impaired renal function (defined as effective glomerular filtration rate \< 30ml/min/1.73m2) * coagulation disorders * respiratory compromise（requires long term oxygen） * had participated in another research trial involving an investigational medicinal product in the 6 months before randomization