Significance of Subchondral Bone Microfracture In The Human Osteoarthritic Tibial Plateau On Cartilage Tidemark Drift

Abstract

Objective: To observe the significance of subchondral bone microfracture in the human osteoarthritic tibial plateau on cartilage tidemark drift.Methods: Human knee tibial plateau cartilage samples with different OARSI grades were obtained, and the numbers of cartilage tidemarks and microfracture lines were determinedafter safranin O staining and compared among groups. Osteogenesis caused by microfracture in subchondral bone was observed and staged according to biological properties.Immunohistochemistry, western blotting, PCR and laser microdissection were performedto detect the biological properties of osteogenic areas caused by microfractures.The accompanying relationship between the ossification process and new tidemark formation inosteogenic areas caused by microfractures was then evaluated.Results: With the increase in OARSI grade, the numbers of cartilage tidemarks and subchondral bone microfracture lines in human knee tibial plateau cartilage tissue samples showed increasing trends.The subchondral bone microfracture line was observed toextend as far asthe basal area of hyaline cartilage and cause endochondral osteogenesis.The endochondral osteogenesis caused by subchondral microfracture was categorized into chondrocyte,calcareous sedimentary and ossification stages. A new tidemark appeared in the osteogenic region near the hyaline cartilage when the ossification process of the osteogenic region was completed.Conclusions:Endochondral osteogenesis canoccur at the base of hyaline cartilage induced by microfractures in the tibial plateau subchondral bone. A new cartilage tidemark can form on the side of the osteogenic tissue close to hyaline cartilage when the process of osteogenesis is completed.There is a positive correlation between the degree of cartilage tissue degeneration and the number of tidemarks in articular cartilage.