Morphological and mechanical study on the effects of experimentally induced inflammatory knee arthritis in rabbit long bones.

Inflammatory knee arthritis was induced by intraarticular injection of carrageenan twice a week for a total of 6 weeks in New Zealand White rabbits and the effects of the arthritis on the morphological and mechanical properties of the adjacent femur and tibia were evaluated 8 weeks after the first injection. Carrageenan-induced knee arthritis resulted in severe osteopenic changes and a dramatic decrease in bone strength of the entire ipsilateral femur and tibia, including the femoral head and distal tibia, but not the contralateral femur and tibia and the remote humerus. The osteoporotic changes of the adjacent bones of the inflammatory arthritic knee are the basis for the reduced mechanical strength of these bones. These findings may have clinical significance with regard to the mechanisms and consequences of osteoporotic changes in patients with rheumatoid arthritis.