Ask a PT Response: "Physical therapy would definitely be a useful option for the treatment of tendonitis at the knee and for osteoarthritis. If there are deficits in strength, range of motion, flexibility, posture and gait, physical therapists can help with achieving gains in these areas which in turn could lead to decrease stresses at the knee and an improvement with the condition, especially since the doctor believes that the tendonitis is secondary to the arthritis at the knee. PT's can also help manage the tendonitis itself through the use of various modalities. Best of luck to your mother."