The study was reported according to CONSORT statement. Eligibility criteria for this study were patients aged between 40 and 80 years who were diagnosed with primary osteoarthritis of the knee scheduled to undergo unilateral TKA. The exclusion criteria were (i) severe deformity that required stem or metal augmentation, (ii) previous knee surgery, (iii) allergy to the drug used in the study, (iv) chronic kidney disease (estimated glomerular filtration rate < 60 mL/min), (v) liver cirrhosis, and (vi) refusal to participate. The patients were blinded to the intervention and randomly assigned into 2 groups: epinephrine (EN) and control (C) groups. A block-of-4 randomized sequence was generated using www.randomization.com and concealed by opaque envelopes. The process was done by a research coordinator who was not involved in the study. The flow of patients in this study is summarized in Figure 1 .
3 experienced arthroplasty surgeons (RN, KC, and CP) performed all the procedures with the same surgical techniques. All operations were carried out under spinal anesthesia and adductor canal block. A tourniquet pressure of 300 mmHg was inflated before skin incision and deflated after skin closure. A mini-medial parapatellar approach was used (5 (link)). The neutral mechanical axis of the lower limb was restored. After trial components removal, a scrub nurse, who did not take part in the study, opened the concealed envelope and assigned the patients to the allocated treatment.
LIA, including 20 mL 0.5% bupivacaine, 30 mg ketorolac, and 0.6 mg epinephrine (1:1000) was used in the EN group while in the C group similar ingredients without epinephrine were used. LIA in each group was diluted with normal saline until the total volume was 100 mL. The surgeon was blinded to the intervention and injected LIA into 4 areas (25 mL per area); (i) posterior, posteromedial and posterolateral capsules, (ii) medial gutter, (iii) lateral gutter, and (iv) quadriceps muscles, retinacular tissue, pes anserinus, suprapatellar and infrapatellar fat pads (6 (link)). Cemented Nexgen LPS-Flex fixed bearing prostheses (Zimmer, Warsaw, IN, USA) were implanted without patellar resurfacing. A vacuum drain was placed intra-articularly and retained for 48 hours after surgery. The same rehabilitative program was started on the 1st postoperative day. For postoperative pain management until 48 hours after surgery, all patients received intravenous parecoxib (40 mg) every 12 hours and oral acetaminophen with codeine (300/15 mg) every 6 hours. Intravenous morphine (2 mg) every 2 hours was given as a rescue drug. All patients and outcome assessors were blinded to the intervention. Postoperative visual analog pain score (VAPS, ranging from 0 [no pain] to 10 [extreme pain]) and morphine consumption were recorded every 6 hours until 48 hours after TKA. Before discharge, postoperative range of motion (ROM) and complications including infection, skin necrosis, and wound complication were also recorded.
3 experienced arthroplasty surgeons (RN, KC, and CP) performed all the procedures with the same surgical techniques. All operations were carried out under spinal anesthesia and adductor canal block. A tourniquet pressure of 300 mmHg was inflated before skin incision and deflated after skin closure. A mini-medial parapatellar approach was used (5 (link)). The neutral mechanical axis of the lower limb was restored. After trial components removal, a scrub nurse, who did not take part in the study, opened the concealed envelope and assigned the patients to the allocated treatment.
LIA, including 20 mL 0.5% bupivacaine, 30 mg ketorolac, and 0.6 mg epinephrine (1:1000) was used in the EN group while in the C group similar ingredients without epinephrine were used. LIA in each group was diluted with normal saline until the total volume was 100 mL. The surgeon was blinded to the intervention and injected LIA into 4 areas (25 mL per area); (i) posterior, posteromedial and posterolateral capsules, (ii) medial gutter, (iii) lateral gutter, and (iv) quadriceps muscles, retinacular tissue, pes anserinus, suprapatellar and infrapatellar fat pads (6 (link)). Cemented Nexgen LPS-Flex fixed bearing prostheses (Zimmer, Warsaw, IN, USA) were implanted without patellar resurfacing. A vacuum drain was placed intra-articularly and retained for 48 hours after surgery. The same rehabilitative program was started on the 1st postoperative day. For postoperative pain management until 48 hours after surgery, all patients received intravenous parecoxib (40 mg) every 12 hours and oral acetaminophen with codeine (300/15 mg) every 6 hours. Intravenous morphine (2 mg) every 2 hours was given as a rescue drug. All patients and outcome assessors were blinded to the intervention. Postoperative visual analog pain score (VAPS, ranging from 0 [no pain] to 10 [extreme pain]) and morphine consumption were recorded every 6 hours until 48 hours after TKA. Before discharge, postoperative range of motion (ROM) and complications including infection, skin necrosis, and wound complication were also recorded.
