Fig. 1From: Does lower educational attainment increase the risk of osteoarthritis surgery? a Swedish twin studyThe hazard ratios (HR) per 3Â years of education with 95% confidence intervals (CI) for knee and hip OA surgery, for unmatched and matched dizygotic (DZ) and monozygotic (MZ) twins. Models were adjusted for sex, birth cohort, and place of residence at age 18Back to article page