Fondaparinux is an antithrombotic agent having already received a regulatory approval by the European Authorities in venous thromboembolic event prevention after major orthopaedic surgery, as total hip replacement (THR), total knee replacement (TKR), hip fracture (HF). The bleeding risk associated with this prescription is highly related to renal function evaluated by creatinin clearance (CrCl). In order to reduce the bleeding risk, it has been proposed to prescribe fondaparinux 1,5 mg/day in patients with a CrCl between 20 and 50ml/mn instead of 2,5mg/day (European MMA). In the meantime, this approval is essentially based on simulated pharmakinetic data without any support of clinical data.

prospective, multicentre, open-label study evaluating the safety profile of fondaparinux 1,5 mg/day, subcutaneously administered, in patients with a renal impairment defined by a CrCl between 20 and 30 ml/min and undergoing a major orthopaedic surgery.

Fondaparinux 1,5mg/day subcutaneously administered during post-surgery 1 to 10 days with the 1st treatment administration performed 6 to 8 hours after the end of surgery.

Screening visit : > 7 days before inclusion visit if THR and TKR Inclusion visit : day of surgery Visits with blood drawing: 3 visits scheduled during 1 to 10 days of treatment period Study end of treatment visit: D1 to D10 Study end visit: 1 month ± 15 days

Inclusion Criteria:

• • age > 18 years old,

  • undergoing a major orthopaedic surgery (THR, TKR, HF) whatever procedure techniques are used, 1st indication or 2nd indication,
  • requiring an antithrombotic prophylaxis,
  • presenting a renal impairment defined by a creatinin clearance (CrCl) between 20 and 50 ml/min calculated by Cockcroft and Gault's formula,
  • having signed the inform consent form.

Exclusion Criteria:

• contra-indications to fondaparinux,
• history of heparin inducted thrombopenia (HIT),
• platelets < 100 g/l.