Modeling of Healing of Intra-Articular Fractures of Long Tubular Bones in Rats

Background : We present a new original method of modeling an intra-articular fracture of the long tubular bone in laboratory animals. Objective : To create a new experimental model of an intra-articular fracture of the long tubular bone and to approve it for comprehensive evaluation of morphofunctional parameters of cartilage and bone healing. Materials and methods : The experiment was performed on 30 white sexually mature Wistar rats. Modeling involved layer-by-layer dissection of tissues along the anteromedial surface and formation of an incomplete fracture of the femoral medial condyle using a sharp L-shaped working end of an 0.2 × 0.2 сm instrument perpendicular to the medial condyle with a slight single muscle force. The rats were euthanized in groups of 10 animals on days 7, 14, and 30. We performed knee radiography and determined blood osteocalcin and BMP-7 levels. The Mankin score was used in the histological evaluation of the articular cartilage changes. The groups were compared using the Kruskal-Wallis test. P < .05 was considered statistically significant. Results : We noted statistically significant differences ( P < .0001) when comparing the groups using the Mankin score. The post hoc test revealed statistically significant differences in the Mankin scores between days 7 and 14 ( P = .014) and between days 7 and 30 ( P < .0001). Group comparisons showed no statistically significant differences in blood osteocalcin levels ( P = .518). However, there were statistically significant differences ( P = .0028) between the groups in blood BMP-7 levels. The post hoc test revealed statistically significant differences in blood BMP-7 levels between days 7 and 14 ( P = .048) and between days 14 and 30 ( P = .0195). Conclusions : The developed experimental model of intra-articular fractures of long tubular bones allows for a comprehensive assessment of reparative processes of cartilage and bone tissue. The model is close to the real mechanism of pathology development.