The numerical ratio between the value of the thrombin generation test performed without soluble thrombomodulin and the value of the thrombin generation test performed in the presence of soluble thrombomodulin, performed pre-surgically, could predict the risk of early venous thromboembolism after placement of total hip or knee prosthesis.

Inclusion Criteria:

• The patient must have his consent and signed the consent form.
• The patient must affiliated or a beneficiary of a health insurance plan.
• The patient is at least 18 years old
• Patient with an indication of total hip prosthesis or total knee replacement surgery set unilateral

Exclusion Criteria:

• The patient is participating in another interventional study.
• The patient is in an exclusion period determined by a previous study.
• Minor patients, people in emergency situations.
• The patient is under the protection of justice, guardianship or curatorship.
• The patient refuses to sign the consent.
• It is not possible to inform the patient.
• The patient is pregnant, parturient, or breastfeeding.
• The patient has a contraindication (or incompatible drug combination) to drug thromboprophylaxis applied according to good clinical practice and recommendations of learned societies
• Long-term anticoagulant therapy for personal thrombotic history.
• Known hemorrhagic disease.
• Haemorrhagic risk perceived during the consultation of preoperative anesthesia, leading to modify / develop the usual thromboprophylaxis.
• Chronic liver disease.
• Chronic renal failure with calculated clearance <30 ml / min.
• Extreme body mass index: <18 kg.m-2 or> 40 kg.m-2
• total hip prosthesis or total knee prosthesis in the immediate aftermath of a bone fracture.
• total hip prosthesis resumption.
• Installation of more than one joint prosthesis.
• Surgery in the previous 3 months.
• Infective push in the previous 3 months.
• Indication of haemostatic treatment for abnormal haemorrhagic risk.
• Severe impairment of renal function with a calculated clearance <30 ml / min.
• Contraindication (allergic, metabolic, other ...) to usual drug thromboprophylaxis.
• Condition requiring dosage adjustment of drug thromboprophylaxis.
• Indication to put in place intermittent pneumatic compression for perioperative thromboprophylaxis.