Objective: To analyze a population-based cohort of women in order to establish normal values of joint space width (JSW) and to evaluate the existence of age-related joint space loss (JSL).
Methods: Knee radiographs were performed 4 years apart in women from the OFELY (Os des Femmes de Lyon) Cohort. Posteroanterior radiographs of both knees were taken in semiflexion with a standardized fluoroscopically assisted protocol. Radiographs were qualitatively evaluated using a scoring system based on the Altman score that assessed joint space narrowing, osteophytes, and sclerosis for each tibiofemoral compartment and each side. For quantitative assessment, radiographs were digitized using a video camera, and specific software was used to measure JSW in every compartment.
Results: We evaluated the radiographs of 606 women (ages 39-90 years, mean 62 years) and found that in all subjects, JSW significantly decreased with age in every compartment (r = -0.12 to -0.16, P < 0.001), including in 358 subjects without any radiographic abnormality related to osteoarthritis (OA) at baseline. The longitudinal analysis confirmed a significant loss over 4 years of approximately 0.30 mm (6%) for the medial compartment. Multiple regression analysis did not identify significant predictors of JSL among clinical risk factors and biochemical markers of bone and cartilage turnover.
Conclusion: In this first longitudinal study of a population-based cohort of women, we have established normal values of JSW and shown that JSW decreases with aging, especially at the medial compartment, even in subjects without any radiographic abnormalities related to OA.