The main objective for this study is validation for the proposed risk stratification tool, by evaluating the clinical outcomes for its use post TKR Surgeries. For this objective, the design that is used is Randomized Trial.

All patients that will have total knee replacement, in a given period of time in both medical centers; Prince Sultan Military Medical City (PSMMC) and King Abd Allah University Hospital (KAAUH) in Princess Noura University, will be randomly separated into 2 groups; in the first group (A): Venous thromboembolism (VTE) risk stratification tool (which is prepared by a clinical pharmacist) will be applied to choose the tailored extended VTE prophylactic agent. While in the second group (B), the risk stratification tool will not be used, rather it will follow the routine hospital protocol for choosing the VTE prophylactic agent, which is Caprini: a standard validated model. Then each group of patients will be followed till 35 days post-operation, during which all VTE or bleeding events should be recorded.

Inclusion Criteria:

1. Male or Female patients who are planned for elective TKR surgery (primary only).
2. Agreed to sign the Informed consent form (ICF).
3. Patients aged older than 18 years.

Exclusion Criteria:

1. Patients receiving anticoagulant for treatment.
2. Patients with a history of DVT or PE were excluded from the study due to the marked increase in the risk of recurrent VTE compared to the general risk of (7% vs. 0.1%); (Fahrni, 2015).
3. Patients with renal or hepatic failure, renal failure is defined as end-stage kidney disease (on dialysis); hepatic failure is defined as complete liver cirrhosis.
4. Pregnant woman.
5. Revision surgeries.