Welcome AT HCM.
I have read details in your question completely.
Your wife has swelling in knee since last few days with problem with movement of knee.The presence of just enlarged lymph node
does not guide the diagnosis of TUBERCULOSIS
AT Knee.It is also not a common in present era.
I will advice you to have some specific test like RAPID METHOD BACTAC test.
If tuberculosis is suspician then you should have a biopsy
of the knee.
This is a method by which a part of the thickened synovium or inner lining is taken & examined under microscope to check the characteristics related with tuberculosis.
If this comes positive then she will get relief from anti tubercular medicines & traction therapy.
Hope this will help you.
Wish you a happy & healthy life.