Microscopic Examination of Foot Joints Components in Charcot Arthropathy Complicated by Osteomyelitis

Background. Charcot arthropathy is a serious medical and social problem. Histological studies of foot joints components in Charcot arthropathy complicated by osteomyelitis are few. The purpose of this study was to assess structural changes in the articular cartilage and subchondral bone of the foot joints in Charcot arthropathy complicated by osteomyelitis. Materials and Methods. The bone-cartilage fragments of the ankle, subtalar and metatarsophalangeal joints with the surrounding soft tissues of 20 patients with Charcot arthropathy complicated by chronic osteomyelitis were examined. Part of the material was fixed in neutral formalin. All samples were subjected to standard histological processing. Paraffin sections were stained by Masson’s tricolor method, hematoxylin and eosin. Part of the material was embedded in epoxy resins. Then semi-thin sections were stained with methylene blue and basic fuchsin. Histological preparations were studied by digitizing images under the AxioScope A1 microscope (Carl Zeiss MicroImaging GmbH, Germany).The phase of chronic osteomyelitis inflammation was assessed semi-quantitatively using the histopathological scale by A. Tiemann et al. (2014). Results. In 80% of the patients, the inflammatory phase of chronic osteomyelitis was characterized as active and subacute. In all cases, the areas with full-layer of articular cartilage unweaving, up to the subchondral zone, with cartilaginous tissue fragments rejection into the joint cavity were revealed. Cytoarchitectonics was disrupted. The main part of chondrocytes was in a state of destruction. The articular surface was covered with pannus. There were no basophilic line and the zone of calcified cartilage. The hyaline cartilage was replaced by granulation and/or fibrous tissue. An inflammatory infiltrates was noted in the superficial and deep areas of the cartilage. The impairment of the structure and/or complete absence of the subchondral bone due to the high activity of osteoclasts in the subchondral zone were revealed. An excessive amount of osteoclasts at the border with the articular cartilage was noted, while the signs of reparative bone formation were poorly expressed. Edema and thickening of the vascular walls of the microvasculature were recorded. Conclusion. The microscopic examination of the foot joints in Charcot arthropathy complicated by osteomyelitis revealed structural impairment and/or complete absence of the subchondral bone due to the high activity of osteoclasts in the subchondral zone. Structural changes in the subchondral bone and synovial pannus led to irreversible destruction of articular cartilage and the penetration of infection. These should be taken into account in surgical planning.

Charcot arthropathy, osteomyelitis histopathology, articular cartilage, subchondral bone