Thanks for the query
Following trauma you have developed hematoma
( collection of blood in tissues). X ray has been done and it is normal. This hematoma has no relation with your artificial knee, venous insufficiency
or plantar fascitis.
Hematoma usually takes one to two week to resolve.
All you need is bed rest
, some antiinflammatory drug with pain killer and may be clot dissolving heparin
containing ointment .
I will suggest you to consult a doctor for proper clinical examination and treatment.