What is risk of further damage to arthritic joints by using pain killers?

None: There is no damage to your joints from taking pain killers. They don't affect your arthritis negatively. Narcotics work on the brain, non-steroidal antiinflammatory medications actually contribute to reducing inflammation, thereby promoting slowing of the arthritic process.

Not Clear: It depends on the pain killer. Old studies have shown that indocin, (indomethacin) an anti-inflammatory could increase joint damage by masking the pain. Films showed progressive joint damage. Using narcotics could in theory cause a charcot like joint - a joint that can be damaged by neurologic loss of protective sensations which we can sometimes see in diabetes and other illness that affect neurology.