Hi, thank you for the questions. The whole aim of knee replacement surgery is to remove pain. So it seems the left replacement was a success, and the right hasn't achieved its desired results.
She should find out from her orthopaedic surgeon why her right side is still so painful. Knee pain after knee replacement can be due to several reasons.
The most important should be whether there are any potential problems/complications with the replacement itself, and this could be infection, cement fracture, malaligment of the implants etc.
Her orthopaedic surgeon should assess her knee and do the relevant investigations do identify any potential problems. A revision knee replacement is one alternative if the identified cause requires a revision.
Knee pain can also be caused from painful tendons, and if physiotherapy doesn't improve the symptoms, a specialist that treats pain would be a useful person to see.
They can do injections to relieve the pain if necessary. Reducing her weight would also help, as this reduces the loading on the knees, and would help to relief some pain.
Hope this helps,
Dr Sean Ng