Suggest Treatment For Severe Knee And Joint Pain

Hi Doctor,My mother is around 50yrs old and she is complaining of knee joint pain, leg pain which she feels more while taking rest or while sleeping and doesn't feel while working. Sometimes she feels difficult to sleep because of excruciating pain. She also feels difficulty/pain while sitting down and getting up...Kindly let us know how to go ahead..
Thanks in advance...
Suresh, Bangalore