Similarities and differences of estrogen in the regulation of temporomandibular joint osteoarthritis and knee osteoarthritis

Abstract

Background. Temporomandibular joint osteoarthritis (TMJOA) and knee osteoarthritis (knee OA) are two kinds of common osteoarthritis (OA) that are characterized by chronic degeneration of soft and hard tissues around joints. Their gender and age differences suggest that there are similarities and differences between the pathogenic mechanisms of TMJOA and knee OA. Objective. To review recent studies on the effect of estrogen on TMJOA and knee OA, and summarize their possible pathogenesis and molecular mechanisms. Sources. Articles up to present reporting the relationship of estrogen and TMJOA or knee OA are included. An extensive electronic search was conducted of databases including PubMed, Web of science core collection. Conclusion. According to epidemiological investigations, TMJOA primarily happens to females of puberty and childbearing age, while knee OA mainly affects postmenopausal women. Epidemiological investigation and experimental research suggest that estrogen may have a different effect on TMJ and on knee. Though estrogen regulates TMJOA and knee OA via estrogen-related receptors (ERR), their pathogenesis and pathway of estrogen regulation are different. To find out the accurate regulation of estrogen on TMJOA and knee OA, specific pathways and molecular mechanisms still need further exploration.