The purpose of this study is to conduct a prospective randomized clinical trial to compare the accuracy of prosthesis, radiographic alignment, total blood loss, the risk of venous thromboembolism between pinless-navigated total knee arthroplasty (TKA) and traditional TKA.

Minimal invasive surgery total knee arthroplasty (MIS-TKA) is an excellent surgical procedure for patients with end-stage knee diseases and can reduce the postoperative complications compared with traditional TKA procedures.

However, MIS-TKA procedures require a long learning curve to avoid malposition of prosthesis. In previous studies have demonstrated that the position of prosthesis and the postoperative mechanical axis are critical factors of outcome. Malposition of prosthesis and deviation more than 3 degrees of mechanical axis will lead to asymmetrical tibia-femoral tracking between prosthesis with the wear of linear, and increase the incidence of prosthesis loosening.

Computer navigation assisted system has been used in TKA procedures for more than one decade and has been proven to improve the accuracy of prosthesis placement and postoperative mechanical alignment. Moreover, navigated TKA avoids the use of intramedullary guide and preserve the medullary cavity of femur, so the risks of bleeding and venous thromboembolism are reduced. However, traditional navigation system requires additional procedure to set reference arrays with pin fixation of femur and tibia. Pin wound complications including bleeding, infection, and iatrogenic fracture were reported. Moreover, traditional navigation system requires conventional TKA approach in which the wound length of the knee will be as long as 15 to 20 cm. Therefore a combination of new navigation system with a MIS technique to perform TKA procedure is required The new pinless navigated system for TKA procedures has been developed, as the navigation tools were fixed in the surgical field without additional pin wounds. This advantage meets the rationale of MIS-TKA to take care of both minimal invasive procedures and accuracy of prosthesis placement. Therefore, the investigators want to investigate the application of this pinless navigation system in MIS-TKA procedures.

Our purpose is to conduct a prospective randomized clinical trial to compare the accuracy of prosthesis, radiographic alignment, total blood loss, the risk of venous thromboembolism between pinless-navigated MIS-TKA and traditional MIS-TKA.

Material and Methods:

The investigators plan to enroll 100 patients who plan to undergo unilateral primary MIS-TKA and will be randomly assigned into two groups. The first group (50 patients) will be treated by pinless-navigation (Stryker, OrthoMap Express Knee Navigation) MIS-TKA, and the second group (50 patients) will undergo traditional MIS-TKA.

The investigators will record the surgical wound length, surgical time cost and calculate daily hemoglobin drainage and total blood loss after TKA procedures for all patients. At 3 months after operation, the whole leg scanography, AP and lat view of knee radiography will be take and the mechanical alignment (MA), anatomic alignment (AA), femoral bowing angle (FBA), and coronal femoral-component angle (CFA), coronal tibia-component angle (CTA) in coronary view and sagittal femoral component angle (SFA), sagittal tibial component angle (STA) in lateral view will be measured. The operating time and surgical wound length in knee full extension will be recorded. All complications including bleedings, wound complications, venous thromboembolism will be recorded.

Study year: one year Expecting Result The investigators anticipate that the position of prosthesis in pinless-navigated MIS-TKA is more accurate or equal to traditional MIS-TKA group. And the total blood loss in pinless-navigated MIS-TKA is less than traditional MIS-TKA group. The complication rate is similar between the two groups

Inclusion Criteria:

1. Patients with osteoarthritis of the knee secondary to degeneration, inflammatory arthritis, gouty arthritis, posttraumatic arthritis, and undergoing primary unilateral minimally invasive TKA
2. Age > 50 years and < 90 years
3. Failure of medical treatment or rehabilitation.
4. Hemoglobin > 11g/dl,
5. No use of non-steroid anti-inflammatory agent one week before operation

Exclusion Criteria:

1. Preoperative Hemoglobin <11 g/dl
2. History of infection or intraarticular fracture of the affective knee
3. Renal function deficiency (GFR <30 ml/min/1.73m2)
4. Elevated liver enzyme (AST/ALT level are more than twice normal range) , history of liver cirrhosis, impaired liver function(elevated total bilirubin level) and coagulopathy (including long-term use anticoagulant)
5. History of deep vein thrombosis, ischemic heart disease, cardiac arrythmia requiring life-long anti-coagulants, or stroke
6. Contraindications of tranexamic acid, rivaroxaban, or the excipients
7. Allergy to tranexamic acid, rivaroxaban, or the excipients
8. Coagulopathy or bleeding tendency caused by organ dysfunction, such as cirrhosis, bone marrow suppression etc.
9. Patient who have active bleeding disorder, such as intracranial hemorrhage, upper GI bleeding, hematuria

This study proposed 1:1 randomization into pinless navigation and conventional technique. Each patient who enrolled in this study will be given sequence study number, and the chief surgeon will draw lots to decide which group will be assigned in. The patient and the independent reviewer are kept blinded