Abstract
Background
Despite the suggestion by Virchow in 1856 that thrombosis was the result of venous stasis, endothelial dysfunction and hypercoagulability there are some fundamental questions which remain to be answered. The published studies fail to provide specific details such as cast type and anatomical location of the thrombosis, but instead focus on the incidence of VTE and which chemical thromboprophylaxis is most effective. Previous studies of VTE in trauma patients have involved small numbers of patients and have not look at the risk medium to long term risk. Most importantly they have not looked at the site of the VTE. This makes interpretation of the link between cast and VTE even more complex.
Methodology
We analysed 1479 consecutive trauma cast applications and the incidence of symptomatic VTE in the six months following the injury. The diagonosis, cast type and site of the VTE was recorded.
Results
The overall incidence of DVT was 2.5% (2.2% distal and 0.3% proximal), 50% occured inthe first 3 weeks, the rest were between 6–13 weeks. The incidence of PE was 0.7%, there was 1 death due to PE.
Achilles tendon injury was a statistically significant risk factor, there were no other conditions with a specific risk. There was no difference between above and below knee cast immobilisation. However all symptomatic DVTs occured in the casted leg.
Discussion
This is the first study to look at long term VTE risk and the site of thrombosis, these findings have implications for VTE prophylaxis. It would appear that the risk of developing symptomatic VTE extends beyound the currently advised treatment period. It also suggests that venous stasis and endothelial damage are more important that hypercoagulability in the development of VTE after cast treatment for trauma. We recommend a programme of exercises within the cast to reduce this risk.
