Assessment of knee osteoarthritis risk following canine tibial prosthetics (pilot experimental morphological study)

Objective was to obtain preliminary data on the knee osteoarthritis risk following canine tibial prosthetics using one-stage osseointegration, external fixation and compression loading. Material and methods The study was carried out on 5 intact (control group) and 3 experimental (experimental group) animals aged 1.8 ± 0.5 years with a body weight of 19 ± 1.2 kg. Osteotomy was performed at the boundary of the upper and middle third of tibia and a PressFit type construct implanted. A special device was used for bone fixation and compression loading of FN = 20 N. Paraffin sections of the articular cartilage and the underlying subchondral bone were used for histomorphometric examination. Results The zonal structure of the articular cartilage and cytoarchitectonics were shown to be maintained in all experimental animals with insignificant destructive changes in the form of impaired homogeneity of the intercellular substance in the upper third of the surface zone. There was a two-fold decrease in the thickness of the calcified cartilage and a 1.9-fold decrease in the thickness of the subchondral bone. The volumetric density of trabeculae in the subchondral bone decreased to 22.31 ± 5.41 % in experimental animals and to 46.94 ± 1.94 % in controls. Complete absence of calcified cartilage and the subchondral bone were observed in one case with vessels and bone marrow pannus invading the noncalcified cartilage. Conclusion Structural changes in the contact zone of the articular cartilage and the subchondral bone seen in the knee following experimental canine tibial prosthetics indicated the risk of developing knee osteoarthritis.