Blood test may predict clot risk after joint surgery

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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.