Hello, I am writing this on behalf of a 74-year old woman I know who has a recurring clot in her leg. In September last year, the woman fell down the stairs in her home, broke her ankle and tore a ligament in the back of her knee. For a week and a day, she was kept in hospital but they could not operate until the clot in her leg had settled. Now, four months later, she is well recovered, walking about but having difficulty getting up stairs but still with a recurring clot in the back of her leg. What might the problem be that the clot is still there?