Applying risk assessment models in orthopaedic surgery: effective risk stratification.

Deep vein thrombosis (DVT) and pulmonary embolism remain important causes of morbidity and mortality. Without prophylaxis, at least 60% of patients undergoing orthopaedic or trauma surgery develop DVT, and the rate may still be as high as 20-45% even with the best prophylaxis available. The rate of thrombosis may be reduced by wider use of established prophylactic measures and targeting more intense prophylaxis to very-high-risk patients. Novel agents such as pentasaccharides and recombinant hirudins may provide more effective prophylaxis in very-high-risk settings, but their optimal use requires accurate assessment of thromboembolic risk. Risk levels are influenced both by the clinical setting and patient factors, such as obesity and malignancy. There is now growing interest in the influence of molecular risk factors, including acquired thrombophilias and congenital coagulation disorders. Activated protein C resistance and hyperhomocysteinaemia have been recently identified as potential risk factors. Further investigations are needed to clarify the individual contribution of different clinical and molecular factors to overall thromboembolic risk, and the effects of interactions between them. Screening for clotting disorders and other additional risk factors may assist identification of very-high-risk patients and allow appropriate targeting of intensive prophylactic therapy.