Overview

This is a prospective, multicenter, observational cohort study designed to externally validate the Trauma-Related Immobilization-related Prophylaxis (TRiP(cast)) score in Tunisian adults with acute lower-limb trauma requiring immobilization and managed as outpatients. The study will assess the ability of the TRiP(cast) score to identify patients at increased risk of symptomatic venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism.

A secondary objective is to evaluate adherence to prescribed thromboprophylaxis and to compare adherence between patients receiving low-molecular-weight heparin (LMWH) and those receiving direct oral anticoagulants (DOACs). Factors associated with treatment adherence, bleeding events, and thromboembolic outcomes will also be investigated.

Patients aged 18 years or older with acute lower-limb trauma requiring immobilization for at least 7 days will be enrolled consecutively and followed prospectively. The decision to prescribe thromboprophylaxis and the choice of anticoagulant will remain entirely at the discretion of the treating physician according to routine clinical practice. Study investigators will not influence treatment decisions. The results are expected to provide external validation of the TRiP(cast) score in the Tunisian population and improve risk stratification and thromboprophylaxis management in ambulatory patients with lower-limb trauma.

Eligibility

Inclusion Criteria:

• Age ≥18 years.
• Acute lower-limb trauma within 72 hours before enrollment:
  • Fracture (e.g., foot, ankle, leg, or distal femur) requiring immobilization, or
  • Grade II or III ankle or knee sprain requiring immobilization, or
  • Acute Achilles tendon rupture requiring immediate non-surgical immobilization.
• Immobilization with a cast or rigid orthosis (e.g., splint or walking boot) expected to last at least 7 days.
• Initial outpatient management in an emergency department or outpatient orthopedic/trauma clinic.
• No planned hospitalization exceeding 24 hours for the injury or its immediate complications.
• Written informed consent provided before study enrollment.

Exclusion Criteria:

• Planned or initial hospitalization for more than 24 hours.
• History of venous thromboembolism within the previous 3 months.
• Current oral or injectable anticoagulant therapy for another indication.
• Known major contraindication to anticoagulant therapy, including:
  • Active bleeding.
  • Untreated active peptic ulcer disease.
  • Severe thrombocytopenia (platelet count \<50,000/mm³).
  • Severe hepatic impairment.
  • Severe renal impairment (estimated creatinine clearance \<30 mL/min using the CKD-EPI equation).
• Open lower-limb trauma requiring immediate surgery (except simple fracture reduction and immobilization).
• Inability to understand the study procedures or provide written informed consent.
• Pregnancy or breastfeeding.
• Concurrent participation in another clinical study that may interfere with the objectives of the present study.