Post-anterior cruciate ligament reconstruction (ACLR) hemarthrosis may result in increased pain thus delaying postoperative rehabilitation, which may eventually lead to arthrofibrosis and a functional deficit. Many antifibrinolytic agents, including tranexamic acid (TXA), have been used in orthopedic surgeries to reduce postoperative bleeding.The purpose of this study is to evaluate the effect of intra-articular injection of TXA in patients receiving arthroscopic ACLRs. Patients were randomized into two groups. Group 1 patients (TXA group) received the index procedures with a 10 mL intra-articular injection of TXA. Group 2 (control group) patients received the index procedures without TXA injections. An intra-articular suction drain was placed recorded 24 h postoperatively. Clinical evaluations using an IKDC functional score, range of motion (ROM), and a Visual Analogue Scale (VAS) pain score were performed at postoperative day 3 and week 4.

TXA group patients received ACLRs and a 10 mL intra-articular injection of TXA after the procedure. The control group patients only received ACLRs without TXA injections. Randomization was done on the day of the surgery, by an independent investigator who did not participate in the surgery, using the permuted block randomization technique.

The same surgeon treated all patients enrolled in this study. Spinal anesthesia was given to all patients and a pneumatic tourniquet was routinely used. In brief, through a 3 cm incision over the medial proximal tibia, semitendinosus (ST) and gracilis (Gr) tendons were harvested from the distal insertion. Tendons were quadrupled and whip stitched by No. 2 and No. 5 Ethibond sutures (Ethicon, Somerville, NJ). The diameters of the folded tendons were determined by using sizing cylinders with incremental size changes of 0.5 mm.The femoral sockets were created at about the 1:30 position (left knee), through the anteromedial portal. The tibial tunnel was created with an ACUFEX guide (Smith & Nephew, Andover, MA). The diameters of the socket were created in the same manner as the diameter of the folded graft. At tibial site, grafts were fixed with bioscrews (BIORCI-HA, Smith & Nephew) at 30 degrees of knee flexion. The screw and the tunnel sizes were the same. After completion of the procedure, a suction drain (Zimmer HEMOVAC, Warsaw, IN) was placed at the superior lateral aspect of the joint. Ten mL of TXA (100 mg/mL) (Daiichi Sankyo, Tokyo, Japan) was injected into the joint at the end of the operation and the drain was clamped for 2 h.

Clinical evaluations The volume of drainage was recorded 24 h after surgery. The grade of hemarthrosis, as previously described by Coupens et al.,was also documented at day 3 and week The range of knee motion and the IKDC functional score were evaluated 4 weeks post-surgery. The VAS was documented at postoperative day 3 and week 4.

Statistical analysis. All data are expressed as a mean and standard deviation (SD). The amount of drainage or functional scores between different groups were compared with an independent t test.

All statistical analyses were conducted using SPSS version 11.0 (SPSS Inc., Chicago,IL). Differences were considered significant when the p-value was < 0.05.

Inclusion Criteria:

1. patient agreed to participate in this study, signed an informed consent document.
2. patients receiving arthroscopic ACLR with autologous hamstring grafts

Exclusion Criteria:

1. previous knee procedures on the same side
2. renal disorder or insufficiency
3. abnormal coagulation profile
4. refused to participate in this study