Ten-year trends in values of joint space width and osteophyte area of knee joints: comparison of the baseline and fourth ROAD study surveys

Objective Considering the joint space width and osteophyte area (OPA) of the knee joints of Japanese adults, this study elucidated the ten-year trends in medial minimum joint space width (mJSW) and OPA using data of two independent cohorts from a population-based cohort study. Methods The baseline survey of the Research on Osteoarthritis/Osteoporosis Against Disability study was conducted from 2005 to 2007; 2,975 participants (1,041 men, 1,934 women) completed all knee osteoarthritis (OA) examinations. The fourth survey was performed from 2015 to 2016; distinct 2,445 participants (764 men, 1,681 women) completed identical examinations. The medial mJSW and medial tibial OPA were measured bilaterally using an automated system. Results The mean medial mJSW (standard deviation) was 3.22 (0.96) mm and 2.65 (0.95) mm at baseline and 3.81 (1.20) mm and 3.13 (1.15) mm in the fourth survey for men and women, respectively. The mean medial mJSW in the fourth survey was significantly greater in both men and women in all age groups than at baseline (p<0.01). The mean OPAs in men aged 40–49 and 60–69 years and women aged 40–49, 50–59, 60–69, and 70–79 years were significantly smaller in the fourth survey (p<0.05). The trend in mJSW remained the same even after adjusting for confounding factors in the multivariate analysis, but the trend in OPA was weakened. Conclusions A significant improvement in the medial mJSW within 10 years could decrease the incidence and progression of knee OA and prevent the risk of walking disability.