Microfractures and microcracks in subchondral bone: are they relevant to osteoarthrosis?

Although it has been suggested that stiffening of subchondral bone, due to microfractures, is of primary pathogenetic importance in the breakdown of overlying articular cartilage in idiopathic osteoarthrosis (OA), recent data suggest that stiffening of subchondral bone in early OA plays little role in the etiology of the disease. On the other hand, microcracks in the subchondral plate and calcified cartilage with subsequent reactivation of the secondary center of ossification appear to be a significant pathophysiologic mechanism in idiopathic OA. Microcracks seem to be capable of causing (or at least contributing to) the articular cartilage loss that is characteristic of the arthrotic process. Microcracks in the subchondral plate and calcified cartilage may serve as a focus for the initiation of targeted remodeling.