Current concepts in pathogenesis of acute and chronic osteomyelitis

Purpose of review The term osteomyelitis covers a wide range of inflammatory bone disorders caused by microbial invasion or due to autoinflammatory processes, but furthermore osteomyelitis also occurs at different ages and at preferred localizations in the human skeleton. This article aims to give an overview of the current literature focussing on pathognomonic aspects of osteomyelitis because of microbial invasion. Recent findings Outlining the chronological sequence of osteomyelitis originating from the invasion of microbes finally leading to destruction of bone tissue, the formation and proliferation of biofilm structures play a key role in the development of inflammatory bone disorders. The components of the biofilm on the one hand mediate an immune response leading to an increase of local cytokines and induction of osteoclastogenesis but on the other hand also directly interact with the osteoblasts. As a result, the bone-remodelling process is immensely diminished by induction of proapoptotic pathways, decreased proliferation and differentiation of osteoblasts and an additional promotion of osteoclastogenesis. Summary Although microbial invasion is responsible to be the cause for inflammatory bone disorders, except for an autoinflammatory origin, the underlying and detailed mechanisms in the pathogenesis of osteomyelitis are not yet fully understood, but represent an absolute precondition for the development of effective causal treatment strategies in the future.