Incidence of Deep Vein Thrombosis in the Lower Extremity

Venous thromboembolism (VTE) encompasses both deep vein thrombosis (DVT) and pulmonary embolism (PE).1,2 Factors such as venous stasis, vascular injury, hypercoagulability and major orthopaedic surgery such as hip/ knee replacement or hip fracture surgery increases the risk for thrombosis. Currently there is limited information on the incidence and risk of VTE following ankle fracture surgery and the economic impact on the use of prophylaxis for the prevention of VTE in these patients. Chapter one of this thesis provides a comprehensive literature review highlighting the epidemiology, risk factors, prophylactic modalities used and complications in both medical and surgical patients for the prevention of VTE. Chapter two is a retrospective study that examines this area, in particular, practice patterns in VTE prevention both in-hospital and beyond hospitalisation following ankle fracture surgery. These results showed that most of these patients received low molecular weight heparin (LMWH) and that the overall in-hospital VTE incidence was 2.9% (95% CI: 1.3 - 4.4). There was a 1.5-fold increase risk of VTE at three months post hospitalisation (4.3% (95% CI: 2.3 - 6.2), bleeding rates were low and there were no major complications. This led to a systematic literature review for chapter three evaluating the economic impact with use of pharmacological prophylaxis in major orthopaedic surgery for VTE prevention as well as complications and treatment costs. These results highlighted economic benefits with the use of LMWH compared to difference in healthcare systems. The first two chapters emphasise the importance of immobility for the risk of thrombosis. This is discussed in chapter four together with a summary of the main findings, gaps and future directions. The need to explore the importance of immobility on DVT risk led to a protocol development and ethics approval for the evaluation of the rates of DVT in diabetic foot ulcer patients with total contact casts