1. Department of Orthopaedics and Traumatology; Complejo Asistencial Universitario de Palencia; Palencia Spain
2. Department of Pediatric Orthopedics; Hopital Universitaire Necker Enfants Malades; Assistance Publique Hopitaux de Paris; Paris France
3. Clinical Investigation Unit; Hopital Universitaire Necker Enfants Malades; Assistance Publique Hopitaux de Paris; Paris France
4. Haemophilia Care Centre; Hopital Universitaire Necker Enfants Malades; Assistance Publique Hopitaux de Paris; Paris France