abutment: a masonry support that touches and directly receives thrust or pressure of an arch or bridge
support: supporting structure that holds up or provides a foundation
rheumatoid arthritis: a chronic autoimmune disease with inflammation of the joints and marked deformities; something (possibly a virus) triggers an attack on the synovium by the immune system, which releases cytokines that stimulate an inflammatory reaction that can lead to the destruction of all components of the joint