Legg – Calve – Perthes disease: Modification of the experimental design and its morphological criteria

Legg – Calve – Perthes disease (LCPD) is the most common femoral head osteonecrosis in children. Until now, the knowledge of etiology, pathogenesis and clinical signs is partial and does not provide a coherent view of the disease. Despite modern advances in understanding and diagnosing of the disease, surgical interventions and stress release remain the standard treatment methods. Now there is a need to develop both new strategies for studying the pathogenesis of the disease and choosing methods of its treatment. The aim . Reproduction and development of morphological criteria for the early stage of Legg – Calve – Perthes disease (stages 1–2 by the modified Waldenström classification system). Materials and methods . The research involved 6 young gray giant rabbits (Flandres) aged 3–4 months. The early stages of LCPD were simulated by the pathophysiological model of Kuzhelivsky I.I. et al. (2016) with paraarticular adrenaline injections along with physical activity. We modified the physical activity regime for the subjects by daily free range for 1.5–3 hours. Results . The experiment confirmed the validity of the modified simulation and designed its morphological criteria. The osteochondropathy process was verified histologically, we also revealed the classic signs of damage to subchondral bone and hyaline cartilage as well as abnormal vascularization of cartilage sites and pathological neoangiogenesis. Conclusion . The technique of non-traumatic osteonecrosis simulation in young rabbits featured initial results in reproducing the pathological links of osteonecrosis process. The cartilage tissue featured the loss of isogeneity in chondrocytes structure and their column-like arrangement; its delamination and replacement with fibrous tissue, including fibroblast-like cells and collagen fibers; cartilage neovascularization and persistent mixed hyperemia. In the bone marrow, only the activation of the red blood cell line was noted. The bone tissue featured the abnormality of osteon structure with a mosaic arrangement of trabeculae as well as lacunar resorption, and osteoblast degeneration.