PAIN trial: phase II, single-center, double-blinded RCT comparing the efficacy of high dose of liposomal bupivacaine and standard bupivacaine periarticular injection in relieving immediate postoperative pain after total knee arthroplasty. Study protocol. PPCR [Internet]. 2020 Jun. 26 [cited 2025 Apr. 12];6(2):6-12. Available from: https://journal.ppcr.org/index.php/ppcrjournal/article/view/100