The investigators will include patients who will be schedule for total knee arthroplasty with a diagnosis of osteoarthritis. The patients will be divided in two groups. In both groups a verbal and clear detailed information will be given on the intraoperative approach. The first group will receive topical tranexamic acid and the second group topical platelet rich plasma; both in the surgical site. Both groups will be assessed before and after the intervention with laboratory results (hemoglobin, hematocrit levels) and drainage drain.

Total knee replacement (TKR) surgery is one the most common orthopedic procedure in the world. Morbidity in perioperative TKR is associated with: blood loss, pain, infection, wound complications, stiffness, and thrombotic events. Blood loss and transfusion have been associated with an increased hospital stay, costs, morbidity, and mortality. Indications for blood transfusions are now limited and it is well known that is not a free risk procedure. Complications such as; ABO incompatibility, viral transmission, hemolysis, immunosuppression, and wound infection have been reported.

Literature reports have reported blood loss in TKR ranging from 300ml to 1 liter, and transfusion rate varying from 10-38%. In diminishing hospital cost Moskal J. et al. reported 53.90% of savings and a 100% reduction in working hours of the hospital staff using topical tranexamic acid in TKR. Tranexamic acid is an antifibrinolytic agent that acts inhibiting the plasminogen, stabilizing the blood clot; it is used to stop surgical or traumatic bleeding like in the CRASH-2 trial, demonstrating its efficiency in polytraumatized patients. Tranexamic acid has been used in the last years for blood loss with good results. Due to its systemic effects and past medical history of myocardial infarction, stents, and previous thromboembolic events its intravenous use is limited. In this study, the investigators used topical tranexamic acid and its use has been proven in clinical trials as a secure strategy for blood loss reduction in TKR, without excluding patients with previous thromboembolic events.

Platelet-rich plasma (PRP) is an orthobiologic that has played an important role over the past decade in different areas like; spinal fusion, anterior cruciate ligament reconstruction, osteoarthritis, and tendinopathies. The use of PRP in orthopedics is overrated and true indications for its use and cost-benefit are still unclear. Retrospective studies like Pace T et al in 268 patients did not demonstrate differences in-hospital stay, Postoperative hemoglobin levels, and range of motion using PRP in TKR. Morishita M. et al. in a clinical trial of 40 patients, using intralesional PRP didn´t show any benefits for blood loss reduction in TKR, but good clinical results were observed in clinical scores like Knee injury and Osteoarthritis Outcome Score (KOOS) and Visual Analog Scale (VAS) compared to the control group. Other studies have demonstrated the efficacy of topical PRP in blood loss reduction in TKR.

Due to its high platelet concentration and growth factors contained in the alfa granules; it is used as a hemostatic, analgesic, and antiseptic agent in TKR.

There is a variety of blood loss prevention strategies for TKR and these strategies can be divided into preoperative, intraoperative, or postoperative. This study aimed to compare the use of topical tranexamic acid versus topical platelet-rich plasma.

An Insall knee approach, parapatellar medial will be used in all the patients. After the final cuts of the femoral, tibial and patellar and before placing the final cemented components the experimental intervention of the study will begin.

Group 1. A dose of 2 gr of tranexamic acid (1000mg/10 mL X-GEN pharmaceuticals inc.) is diluted in 80 mL of physiologic solution and will be divided into two applications:

First application: 40 mL of the solution previously prepared is applied over the surgical site and it will be left for five minutes then drained out completely by suction.

Second application: The rest of the 40 mL of solution previously prepared is applied after placing the final TKR cemented components (femoral, tibial, and patellar), over the surgical site and leaving it there without draining it by suction.

Group 2. In the preoperative room with previous premedication, a total of 55 mL of total venous blood is obtained from the forearm (cubital o basilic veins). The blood is carried on 12 sterile tubes using sodium citrate at 3.8% (BD, Vacutainer; Becton, Dickinson and Company, NJ). Blood samples are then transported to the Bone and Tissue Bank for centrifugation (1800 rpm for 10 minutes) to separate blood into the 3 layers (White, yellow and red). The superior layer rich in plasma will be collected in 50 microliters polypropylene tubes (Corning, NY). A final volume of 16 ml of platelet-rich plasma is obtained and transferred to airtight tubes (BD Vacutainer; Becton, Dickinson and Company, NJ). The manipulation of the blood samples is made on laminar flow cabin biosecurity class II (Logic 3440801; Labconco, KC). The platelet-rich plasma will be activated with calcium gluconate at 10% (Pisa Farmacéutica, Jalisco, México) before using it is placed in the surgical site topically. The PRP simple will be divided into two applications, initiating the intervention after the final cuts of the TKR components (like the tranexamic acid group).

First application: 8 ml of PRP are applied over the surgical site and are left for five minutes then drained out completely by suction.

Second application: The rest of the 8 ml are applied over the surgical site after placing the final TKR cemented components (femoral, tibial, and patellar), over the surgical site and leaving it without draining.

Then a primary closure of the wound is performed (capsule, fascia, subcutaneous tissue, and skin) in both groups. Close drainage (Drenovac, NEdren S de R.L. de C.V.) is left intraarticular and fixed to the skin. The drainage will be clamped for 2 hours and removed at the 48 hours of the surgery. Thromboprophylaxis (low weight heparin) will be initiated after 6 hours of the end of the surgery. In the postoperative follow-up, any patient with hemoglobin levels less than 9mg/dL with the anemic syndrome will be transfused.

Inclusion Criteria:

1. Age >18 years
2. Patient candidates for primary total knee replacement
3. Patients willing to participate in the study and sign de inform consent

Exclusion Criteria:

1. Patients with previous history of thromboembolic event in the last 6 months
2. Patients candidates for revision total knee replacement
3. Patients candidates for tumoral total knee replacement
4. Patients candidates for bilateral total knee replacement
5. Patient with cognitive deficit
6. Previous history of coagulopathy

up to 3rd day post operative