Abstract
Peri-articular injections (PAI) have become an important component in many multimodal pain protocols after total knee arthroplasty (TKA). Liposomal bupivacaine has emerged as a highly marketed and touted ingredient for PAI. However, the true efficacy of this material, particularly compared with less expensive PAI “cocktails” such as traditional bupivacaine or ropivacaine, has not been proven to date.
Ropivacaine is considered a long-active local analgesic and in combination with epinephrine, ketorolac and clonidine has been shown to be a very effective PAI in a multimodal pain program. Liposomal bupivacaine has been similarly touted as a long-acting PAI. Initial reports provided support for liposomal bupivacaine PAI's providing similar pain relief as epidurals or femoral nerve blocks. The authors of these studies tout comparable pain control with decreased length of stay attributable to avoiding the side effects of epidurals and regional blocks. However, the ultimate clinical issue relates to how liposomal bupivacaine PAI's compares to traditional PAI cocktail ingredients such as bupivacaine and ropivacaine, which also avoid deleterious effects of regional analgesia, and at a much cheaper price point. Fortunately the highest quality research to date, which includes randomised prospective trials and retrospective controlled cohort studies, have reported consistent results. In a retrospective cohort study comparing a traditional ropivacaine and epinephrine versus liposomal bupivacaine PAI demonstrated no difference between the two groups in inpatient pain scores when used in a comprehensive multimodal pain control program. Further, two prospective randomised trials reported no difference in liposomal bupivacaine PAI compared to a traditional PAI of either bupivacaine or ropivacaine, epinephrine, ketorolac and clonidine. Finally, there have been some authors who contend the efficacy of liposomal bupivacaine PAI's is entirely dependent on a meticulous injection technique, however, comparative studies against traditional PAI ingredients with this recommended technique do not exist.
In summary, the existing data supports that liposomal bupivacaine is an effective PAI that can be used to provide comparable pain relief to that achieved by regional blocks. However, liposomal bupivacaine has not been shown to provide superior pain relief when compared to traditional ropivacaine or bupivacaine PAI's in multimodal pain protocols after TKA. Further, liposomal bupivacaine is prohibitively priced at approximately six times that of ropivacaine-based PAI cocktails. Therefore, the “game changer” is likely the implementation of peri-articular injections as an essential component of multimodal pain control programs and NOT liposomal bupivacaine.
