Use of a Novel, Extended-Release, Dual-Acting, Local Anesthetic in Total Knee Arthroplasty and Total Hip Arthroplasty: Application Technique and Experiences with ZYNRELEF

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) provide many benefits to patients including improved functioning and quality of life. However, postoperative pain can be significant, and is a factor in extending hospitalizations, readmissions, and poor outcomes. HTX-011 (ZYNRELEF™) is an extended-release, dual-acting, local anesthetic consisting of bupivacaine and low-dose meloxicam within a tri(ethylene glycol) poly(orthoester) (TEG-POE) based technology Biochronomer™ polymer for drug delivery. Due to its semi-viscous solution, ZYNRELEF is applied directly onto the pain-generating tissue within the surgical site and stays in the location where it is applied. As a result of dissatisfaction with standard of care injections of ropivacaine, epinephrine, clonidine, ketorolac (RECK), as well as a need to perform more TKAs and THAs in an outpatient setting because of the COVID-19 pandemic, the author began using ZYNRELEF to explore its use in a real-world setting based on positive clinical trial data. A retrospective review was conducted of TKA and THA procedures performed at a single hospital in the United States between February and July of 2022. A standard multimodal pain protocol was used in addition to ZYNRELEF during the surgical procedure. Several patient outcomes were assessed including pain, infection rates, readmission, and acute renal injury. Of the 100 TKAs and 57 THAs performed, most patients (81%) experienced mild pain postoperatively. There were no cases of infection or acute renal injury. Few (3%) patients were readmitted (for any reason). When used as part of a multimodal pain protocol, ZYNRELEF is safe and effective in a real-world, outpatient setting.