Hello and welcome to HCM,
Swelling around the knee joint is most commonly due to
joint effusion.
Effusion is caused due to trauma, infection, inflammation etc.
Spontaneous effusions can occur in
connective tissue disorders or
autoimmune disorders.
Associated pain is probably due to muscle spasm around the knee joint.
A couple of investigations are required before treatment can be started.
Firstly, arthroscopic examination of the knee joint is required.
Arthroscopy will detect presence or absence of fluid in the joint space.
Aspiration of fluid from the joint is required for cytology to know the nature of effusion.
MRI of the knee joint and structures above and below the joint will give more information about the structures around the knee joint and the probable abnormality.
Further treatment can be planned accordingly.
Thanks and take care
Dr Shailja Puri