Subchondral and trabecular bone remodeling in canine experimental osteoarthritis.

INTRODUCTION: We wanted to test the hypothesis that quality changes occur in early-stage arthritic subchondral cancellous bone after acute subchondral damage. So far, not much attention has been paid to changes of the subchondral bone after traumatic subchondral lesions.
MATERIALS AND METHODS: With an established animal model, we produced pure subchondral damage without initial affection of the articular cartilage in 12 Beagle dogs under MRI and histological control. We utilized bone histomorphometry to evaluate bone turnover, its structure and the articular cartilage 6 months after the initial damage.
RESULTS: On follow-up, bone remodelling was indicated, e.g. by a significant increase in the trabecular bone volume and thickness, osteoblast number and osteoid surface and a decrease in the trabecular number in all 12 samples. Several other parameters showed a tendency, e.g. osteoblast surface and osteoclast number. Cartilage analysis showed degenerative changes in ten of 12 samples that had not shown any evidence of damage during the initial examination. DISCUSSION: Our investigation indicates a significant deterioration in the architecture of the cancellous bone with degenerative changes of the overlying articular cartilage after subchondral lesions, which change the mechanical properties.