ex vivo flexural mechanical properties of bovine bone plates after tibiae osteosynthesis in rabbits

ABSTRACT. Drago M.A., Drago M., Cerqueira H.D.B., Tiburcio M.F., Souza G.B., Barbosa D.H., Santos C.M.L., Silva R.V. & Freitas P.M.C. [Ex vivo flexural mechanical properties of bovine bone plates after tibiae osteosynthesis in rabbits.] Avaliação ex vivo das propriedades mecânicas em flexão de placas ósseas bovina na osteossíntese de tíbias de coelhos. Revista Brasileira de Medicina Veterinária, 37(3):245-249, 2015. Programa de Pós-Graduação em Ciências Veterinárias, Universidade Federal do Espírito Santo (UFES), Alto Universitário, s/nº, Bairro Guararema, Alegre, ES 29500-000, Brasil. E-mail: manudrago@hotmail.com The use of materials produced from bovine bone has been proposed in the manufacture of implants such as pins, plates and screws, due to their osteoinductive and osteoconductive properties or functions of bone graft. However, structural and mechanical aspects must be evaluated prior to the use, in vivo of bone implants. The aim of this study was to evaluate mechanical strength, through a mechanical bending test, of plates produced from bovine cortical bone, used to repair fractures of the tíbia of rabbits ex vivo. Twenty six plates were manufactured from bovine cortical bone and stored in saturated salt solution. Three study groups were used: group GP (n = 10), made up of the bone plates; GTP group (n = 16), rabbit tibia osteotomized and stabilized with bone plates and four screws and Group GT (n = 10), intact tibia. A three-point bending biomechanical test was used to determine the maximum tension, maximum deflection, and stiffness. The results were submitted to Kruskal-Wallis test (p <0.05) and the Dunn test. Comparing GT with the GTP, an 80% reduction was observed in maximum tension. Also noted was a reduction of 87% in maximum tension when comparing GP with GTP. Therefore, the bovine bone plate had a higher maximum tension then the intact rabbit tibia. There was a reduction of 52% in the rigidity of GTP to GT. No significant difference was observed between this force when GPT and GP were compared. There was significant difference among the three groups with respect to maximum deflection, which showed an increase of 100% and 30% in the GTP and GP groups, respectively, when compared to the GT. This study, therefore concluded, that bone plates used to repair fractures of the tibia of rabbits ex vivo presented inferior mechanical properties when compared to intact tibia.