Traumatic lesions are the leading causes of admission to the emergency center (39%), isolated non-surgical lower limbs trauma are in the foreground. Two recent meta-analyzes suggest the value of Low Molecular Weight Heparins (LMWH) which would reduce symptomatic Thromboembolism Events (TE) in patients with lower limb trauma. However, many recent studies conclude to the need of stratifying the TE risk according to the patient and the nature of his trauma to obtain an individualized therapeutic decision.

The retrospectively established L-TRIP (cast) score allows stratification of the risk without taking into account the type of trauma. The TIP score (Trauma, Immobilization and Patient) was established by consensus of international experts via the Delphi method.

We suggest that the application of the TIP score to rationalize indications of thromboprophylaxis in patients with isolated non-surgical trauma of a lower limb should reduce the rate of anticoagulation prescription without increasing the risk of symptomatic thromboembolic complications with a direct benefit for patients and medico-economic for the society.

All patients admitted to the Emergency Departments for a nonsurgical isolated lower limb trauma necessitating rigid or semi-rigid immobilization, will be assessed for possible participation.

After the physicians had obtained the no-opposition of the patient, they will fill a questionnaire. This questionnaire includes the treatment chosen by the physician, the type of trauma, the type of immobilization chosen, and the patient's thromboembolic risk factors in order to calculate the TIP and L-TRIP (cast) scores retrospectively.

Phone follow-up will occur within 3 months to gather clinical event data (any signs of VTE, any bleeding events).

Inclusion Criteria:

• Consultation in one of the emergency departments of the participating centres
• Isolated unilateral lower limb injury not requiring surgery
• Lower limb rigid or semi-rigid orthopedic immobilization (i.e. brace of plaster cast) for at least 5 days.
• Full insurance cover

Exclusion Criteria:

• Any anticoagulant or antiplatelet treatment prior to trauma
• Contra-indication to fondaparinux or LMWH
• Factors rendering 3-month follow-up impossible
• Imprisonment
• Inability to provide informed consent

All patients admitted in the Emergency Department for an isolated lower-leg trauma injury non surgical requiring semi-rigid or rigid immobilisation.