To investigate factors associated with absence of osteoarthritis (OA).
In 82 well-functioning 90-year-old participants from a cross-sectional birth cohort, radiographs of hands, hips, and knees were acquired and scored according to the Kellgren and Lawrence (K-L) method for determining OA. A score of ≥ 2 was considered as OA. 'Free from OA' was defined as no hip or knee OA and less than three hand joints with OA. Logistic regression analyses were used to investigate associations with absence of OA.
Absence of hip, knee, and hand OA was seen in 63, 51, and 29% of participants, respectively. Joints on the left and right side of the body were equally affected. Sixteen per cent of 90-year old participants were 'free from OA'. Absence of knee OA was associated with being male. A family history of finger nodes was negatively associated with absence of hip and hand OA. Body mass index (BMI) was negatively associated with 'free from OA', and also with absence of hip and knee OA. A history of heavy occupational work was associated with 'free from OA' [odds ratio (OR) 7.2, 95% confidence interval (CI) 1.3-39.9] and with absence of hand OA in particular (OR 2.7, 95% CI 1.0-7.1).
In 90-year-olds, absence of OA is associated with male sex, a normal BMI, absence of familial predisposition for OA, and, contrary to our expectation, heavy work. Further research in protective genetic factors is needed.