They questioned 2,471 patients who had DVT about any injuries, surgery, plaster casts or immobilisations they had prior to developing the clots. They were then compared with 3,534 controls without DVT.
Almost 12% of the patients who had DVT had a minor leg injury, such as a sprained ankle or ruptured muscle, three months prior to developing the clot. Only 4% of the clot-free control group had injured their leg in the same time period.
The authors said: ‘Minor injuries that do not require surgery,
a plaster cast or extended bedrest were associated with a threefold greater relative risk of venous thrombosis.’
The link was strongest when the injury had occurred in the month before the clot formed, they added, and the risk was dramatically higher in those genetically predisposed to DVT.
Kim Carter, DVT nurse specialist at Portsmouth Hospitals NHS Trust, said the study findings were what she would have expected.
‘Even minor injuries of the lower limb can be associated with quite extensive oedema or swelling, which has the potential to obstruct venous flow and increase the risk of DVT,’ she told NT. ‘All localised damage to the vessel will have an effect.’
The authors suggested that, as patients with minor injuries were likely to visit a general practice, high-risk cases should be identified in primary care and prophylactic treatment started.
But Ms Carter warned: ‘The risks and benefits would have to be assessed properly, because pharmacological prophylaxis will increase the amount of bleeding and bruising around the injury.
‘Bleeding into a knee joint after ligament rupture could increase the risk of infection and long-term problems.’
Archives of Internal Medicine (2008) 168: 21–26