Abstract Background Total knee arthroplasty (TKA) is a standard treatment for end-stage degenerative knee disease. Most patients will experience moderate-to-severe postoperative knee pain, significantly affecting rehabilitation. However, controversy remains regarding the efficacy of adding the interspace between the popliteal artery and capsule of the knee (IPACK) into multimodal analgesia protocol. Methods PubMed, Medline, Embase, Cochrane Library, and other databases were searched from inception to February 1, 2021. Studies comparing patients receiving IPACK to patients not...