Osteoarthritis and risk of fractures.

We conducted a case-control study on the effects of osteoarthritis (OA) on the risk of fractures. There were 124,655 fracture cases and 373,962 age- and gender-matched controls. The main exposure was OA, and the main confounders were use of diuretics, antihypertensive drugs, and pain medication. OA was associated with a decreased risk of any fracture and of hip, forearm, and spine fractures. In general a decreasing trend in the risk of fractures was present with increasing time sine diagnosis of OA. The effect on fractures in areas rich in cortical bone such as the hip in general was larger than effects on skeletal sites rich in trabecular bone such as the spine. OA in the hip and knee, in general, was associated with a decreasing risk of fractures with time since diagnosis of OA, while this was not the case for OA in other locations. OA seems to be associated with a decreased risk of fractures at multiple skeletal sites as well as sites far from the location of OA. This may indicate systemic effects on bone strength, especially in areas rich in cortical bone.