Venous thrombosis following lower-leg cast immobilization and knee arthroscopy: From a population-based approach to individualized therapy.

Venous thromboembolism (VTE) is a major complication following lower-leg cast immobilization and knee arthroscopic surgery. In this review, we aimed to give a comprehensive overview of the literature on the epidemiology, prevention and prediction of VTE in these patients. First, the cumulative incidence of VTE was estimated by performing a meta-analysis in untreated patients only. In lower leg-cast patients with various injuries, asymptomatic VTE occurred in 18.0% (95%CI 12.9 to 23.1) and symptomatic VTE in 2.0% (95%CI 1.3 to 2.7). In knee-arthroscopy patients, asymptomatic VTE was seen in 5.9% (95%CI 3.9 to 7.9) versus a symptomatic rate of 0.6% (95%CI 0.4 to 0.7) following heterogeneous types of arthroscopic knee procedures. Second, the efficacy of thromboprophylaxis was determined by performing a meta-analysis of all RCTs that have been performed till date. Following knee-arthroscopy, there was no clear benefit of thromboprophylaxis on the prevention of symptomatic VTE (RR 0.65, 95%CI 0.23 to 1.81), while in contrast, this seemed to prevent asymptomatic DVT. In lower-leg cast patients, thromboprophylaxis appeared to reduce symptomatic VTE (OR 0.31, 95%CI 0.13 to 0.73). However, the validity of these results may be questioned as many trials had several methodological weaknesses. Concerning the bleeding risk (and costs) of thromboprophylaxis, treatment seems only prompted in high risk patients. Such patients could be identified based on individual risk factors such as higher age, obesity or presence of Factor V Leiden. In conclusion, we propose to use risk assessment models to identify patients at risk and to decide on individualized thromboprophylactic therapy, rather than one standard treatment for all patients.