Though physical therapy is useful in osteoarthritis, several trials have found that physical therapy is only mildly or moderately useful.
Different individuals respond differently to physical therapy.
There are certain exercises, which should be learnt from a physical therapist. Following are some techniques, which I have mentioned here from the article "Role of physical therapy in management of knee osteoarthritis" by G. Kelley Fitzgerald and Carol Oatis.
"The Manual therapy techniques include passive range of motion, passive accessory joint motions (i.e., techniques to distract or glide one joint surface with respect to the opposite joint surface), muscle stretching techniques, or soft- tissue mobilization and massage techniques."
"In the Balance, agility, and functional re-training techniques, simple balance board exercises and practice of transfer techniques in conjunction with standard exercise therapy help."
"Knee taping techniques - Taping the knee gives 7 times more relief than no taping."
Transcutaneous electrical nerve stimulation and foot orthoses are two more techniques.
These are some of the techniques. But I would suggest you should consult a physical therapist.