Heres another reason to kick the habit: If you have at least one parent with knee osteoarthritis (OA), if you continue to smoke youre likely to lose knee cartilage as well. According to a recent Australian study reported in the May issue of Arthritis & Rheumatism, there is strong evidence of a gene-environment [IMGCAP(1)]interaction in the development of knee OA. Subjects, average age 45, included 325 patients with cartilage defects, 163 of whom had at least one parent with knee OA and 162 of whom had no family history of OA. Of the total sample, current smokers were found to have a higher prevalence of pain and cartilage loss than former smokers or nonsmokers, regardless of an OA family history. Somewhat unexpectedly, however, researchers also found that the effect of smoking in the development of knee OA was much stronger and more consistent in those with a family history of OA.