Degenerative changes in knee joints as determined by OARSI rat scoring system and osteoarthritis-related joint pain in surgically and chemically induced rat models of osteoarthritis

Abstract

OARSI rat scoring system demonstrated degenerative changes in all rat OA models. Rat MIA model exhibited the loss of chondrocytes, proteoglycans (PG) and collagen matrix in superficial layer of articular cartilage at 2 weeks and in intermediate layer at 4 weeks. Rat ACLT model demonstrated the chondrocyte, PG and collagen matrix loss in superficial layer at 5 weeks. This exacerbated down to tidemark at 10 weeks and was associated with osteophytes and minimal synovial inflammation. Rat MMT + MCLT model exhibited the chondrocyte, PG and collagen matrix loss from superficial layer down to tidemark at 3 and 6 weeks in association with large osteophytes and mild synovial inflammation. Rat ACLT + pMMx model demonstrated the loss of chondrocytes, PG and collagen matrix down to tidemark at 4 and 8 weeks together with large osteophytes and mild synovial inflammation. Static weight bearing decreased in operated knee joints during the first week. Paw withdrawal threshold decreased in operated and MIA-injected knee joints during the first week and at the end of the study.