This prospective randomized controlled trial aims to compare the pharmacokinetic profiles of intraosseous and intravenous tranexamic acid administration in patients undergoing primary total joint arthroplasty. Eligible patients undergoing total hip or total knee arthroplasty will be randomly assigned to receive tranexamic acid either through intraosseous injection or intravenous injection at a dose of 15 mg/kg. Blood samples will be collected at predefined time points to evaluate plasma concentrations and pharmacokinetic characteristics of tranexamic acid. Secondary outcomes include coagulation function, intraoperative blood loss, transfusion rate, and hemoglobin changes. The study aims to provide evidence regarding the pharmacokinetic characteristics and clinical feasibility of intraosseous tranexamic acid administration in joint arthroplasty.

This study is a prospective randomized controlled trial designed to compare the plasma concentration profiles and pharmacokinetic characteristics of intraosseous and intravenous tranexamic acid administration in patients undergoing primary total joint arthroplasty. Stratified randomization will be used in this study. Participants will first be stratified according to the type of procedure, either total hip arthroplasty (THA) or total knee arthroplasty (TKA). Within each stratum, patients will be randomly assigned in a 1:1 ratio to either the intraosseous administration group or the intravenous administration group using a random number table or a computer generated randomization sequence. This approach ensures a balanced distribution of surgical procedures between the two treatment groups.

A total of 80 patients scheduled for primary total hip arthroplasty or total knee arthroplasty will be enrolled. Sample size calculation was based on an equivalence design with a significance level of 0.05 and a statistical power of 80%. Allowing for an anticipated dropout rate of approximately 10%, 40 patients will be recruited within each surgical stratum (THA and TKA). Within each stratum, participants will be randomly assigned in a 1:1 ratio to either the intraosseous administration group or the intravenous administration group using a computer generated randomization sequence, resulting in 20 patients per treatment group in each stratum.

Eligible participants include patients aged 18 to 80 years with osteoarthritis undergoing primary total hip or total knee arthroplasty and classified as ASA physical status I-III. Key exclusion criteria include coagulation disorders, prior pulmonary embolism, tranexamic acid allergy, severe hepatic or renal dysfunction, anticoagulant use, pregnancy, and body mass index greater than 40 kg/m².

Both groups will receive tranexamic acid at a standardized dose of 15 mg/kg. In the intraosseous group, patients undergoing total knee arthroplasty will receive intraosseous injection into the proximal tibial cancellous bone before tourniquet release, while patients undergoing total hip arthroplasty will receive intraosseous injection into the proximal femoral cancellous bone before skin incision. In the intravenous group, tranexamic acid will be administered intravenously.

Arterial blood samples will be collected at 1 minute, 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 6 hours, and 18 hours after administration for plasma concentration analysis and pharmacokinetic curve construction. Secondary outcomes include coagulation parameters, intraoperative blood loss, transfusion rate, and hemoglobin changes. The study aims to clarify the perioperative pharmacokinetic characteristics and potential clinical value of intraosseous tranexamic acid administration in joint arthroplasty.

Inclusion Criteria:

• Age between 18 and 80 years
• Patients scheduled for primary total hip arthroplasty or total knee arthroplasty
• Diagnosis of osteoarthritis
• American Society of Anesthesiologists (ASA) physical status I-III
• Preoperative hemoglobin ≥ 9 g/dL
• Ability to provide written informed consent
• Willingness to comply with postoperative follow up and study procedures

Exclusion Criteria:

• History of coagulation disorders or bleeding disorders
• History of pulmonary embolism
• Known allergy to tranexamic acid
• Pregnancy or breastfeeding
• Severe hepatic or renal dysfunction
• Preoperative anticoagulant therapy
• Body mass index > 40 kg/m²
• Body weight < 45 kg

IPD will not be shared because no public data sharing plan has been established for this study.