RESUMO
BACKGROUND: This study compares the effectiveness of 2 commonly used periarticular injection formulations: liposomal bupivacaine and bupivacaine (EXP) and ropivacaine, epinephrine, ketorolac, and clonidine (ROP) in patients undergoing bilateral total knee arthroplasty or unicompartmental knee arthroplasty. METHODS: Twenty-six total knee arthroplasty patients (52 knees) and 3 unicompartmental knee arthroplasty patients (6 knees) undergoing simultaneous, bilateral arthroplasty were randomized to receive periarticular injections in a blinded fashion. Even birth year patients were selected for PAI of EXP in the right knee and ROP in the left knee. This was reversed for odd birth years. Visual analog scale pain scores for each knee and patient perceived difference in knee functional recovery were recorded during physical therapy, throughout the hospitalization. RESULTS: There was no difference in visual analog scale pain scores between the EXP and ROP injected knees at any time point during the first 2 days after surgery. Postoperative pain scores averaged 41.9 mm (range 0-100 mm) for EXP and 43.1 mm (range 0-100 mm) for ROP. Patients were unable to detect a difference in the functional recovery between their knees on postoperative day 0, 1, or 2. No complications as a result of either periarticular injection occurred. CONCLUSION: Periarticular injections of EXP and ROP are equally effective after knee arthroplasty and patients do not appreciate differences between knees as determined by pain score or perceived functional recovery during the first 2 days after bilateral knee arthroplasty. This study demonstrates that a liposomal bupivacaine injection does not add an incremental benefit for pain control compared to a less expensive injection formulation.