Q. I have recently been diagnosed with osteoarthritis (OA) of the right hip. But instead of having stiffness in the joint, I experience pain radiating down the thigh and stopping at the knee. Does this sound like OA or do you think something else is going on?

A. It's hard to say without examining you; however, what you des-cribe is not unusual for someone with osteoarthritis of the hip. Osteoarthritis of the hip can produce pain that radiates to the knee. Indeed, some patients with OA of the hip complain primarily of knee pain rather than hip pain. Another condition, sciatica, which results from pressure of the sciatic nerve — the major nerve of the leg that runs down behind the thigh from the lower end of the spine before dividing into two branches just above the knee — may also produce pain that radiates down the leg. Distinguishing between these possibilities would require further evaluation, perhaps including X-rays of the spine as well as the hip.

DAVID PISETSKY, MD, PhD Rheumatologist