Prophylaxis of venous thromboembolism in patients with a fracture of the lower extremity being treated conservatively with a below-knee plaster cast.

Although both trauma and immobilisation are two very well known risk factors in
the development of deep vein thrombosis (DVT) no generally accepted strategy
exists in dutch hospitals for patients being treated conservatively in a
below-knee plaster for a fracture of a lower extremity.
Randomised controlled trials differ markedly in their conclusion with some
trials advocating the use of LMWH and others advising against it. Also,
patients being treated in a below-knee plaster cast have never been studied
seperately. Therefore these conclusions are difficult to use for this specific
group.
Both symptomatic and asymptomatic DVT can give rise to substantial morbidity
and mortality, like post-thrombotic syndrome (PTS) and pulmonary embolism (PE).
For years, the low-molecular-weight heparins have been considered to be the
most effective and safest form of prevention of venous thromboembolism in
patients requiring a relative short period of prophylaxis. However, a number of
large recent studies have shown that fondaparinux is more effective in the
prevention of DVT without increasing the risk of side-effects.

The purpose of this study is to determine the need for thromboprofylaxis in
patients being treated in a below-knee plaster cast after trauma of a lower
extremity and if there is, to assess if both of the two tested prophylactic
treatments are suited for this indication.

A prospective, randomised, controlled, single blind, multi-centre trial.

one group will receive 0,3 ml nadroparin s.c. once daily
one group will receive 0,5 ml fondaparinux s.c. once daily
one group recieves no intervention

When patients are assigned to a group with either nadroparin or fondaparinux
they are instructed to inject themselves subcutaneaously once daily during the
immobilisation period.
After removal of the plaster cast all patients will receive a colour duplex
ultrasonography of the affected limb.

The risks are associated with the use of either fraxiparin or fondaparinux and
include bleeding, allergic reactions, reversible eosinophilia, moderate
thrombocytopenia, and elevation of liver enzymes. The chance to develop any of
the above adverse outcomes is 1%.