Comparison of a 3-hole 4.5-mm Dynamic Compression Plate and a 7-hole 5.5-mm Y Locking Compression Plate for Arthrodesis of the Proximal Interphalangeal Joint in Horses-an Ex Vivo Biomechanical Study.

The objective of this study was to compare the biomechanical properties in a single cycle axial loading test and the types of failures in two constructs (a 3-hole 4.5-mm dynamic compression plate (DCP) and 7-hole 5.5-mm Y locking compression plate (Y-LCP)) in equine proximal interphalangeal joint (PIJ) arthrodesis. One limb in each pair was randomly assigned to PIJ arthrodesis using a 3-hole 4.5-mm DCP combined with two transarticular 5.5-mm cortical screws, whereas the contralateral limb was submitted to PIJ arthrodesis using a 7-hole Y-shaped 5.0-mm LCP in conjunction with one transarticular 4.5-mm cortical screw inserted through the central plate hole. Cortical screws were inserted in lag fashion. Constructs were submitted to a single axial load cycle to failure. Construct stiffness, load, and deformation were analyzed. Dynamic compression plate and Y-LCP arthrodesis constructs did not differ significantly and were equally resistant to axial loading under the conditions studied (DCP and Y-LCP group stiffness, 5685.22 N/mm and 6591.10 N/mm, respectively). Arthrodesis of the PIJ using a DCP and two transarticular 5.5-mm cortical screws or a Y-LCP yielded biomechanically equivalent outcomes under the test conditions considered. However, Y-LCP provides less impact in the palmar/plantar bone. Application of Y-LCP with unicortical screws has equivalent biomechanical characteristics of DCP and may be a safe option for PIJ arthrodesis, where potential trauma secondary to applying bicortical screws in the palmar/plantar aspect of the pastern can be avoided.

Morphological and mechanical characterization of chitosan-calcium phosphate composites for potential application as bone-graft substitutes

Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP) - a component of natural bone, and chitosan (CS) - a biocompatible biopolymer. Methods CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C) on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours) on the mechanical properties - compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction) and the chemical composition of the samples, confirmed by FTIR. Conclusion Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.

Estudo anátomo-cirúrgico do cólon transverso do eqüino por acesso paralombar esquerdo / Anatomic and surgical study of the equine transverse colon from left paralombar aprouch

O cólon transverso é um estreitamento do canal alimentar, sujeito a sofrer processos obstrutivos. A ampliação do conhecimento sobre essa estrutura e adjacentes é de grande importância cirúrgica. Neste estudo foram utilizados 10 cadáveres de eqüinos de diferentes raças, idades e sexos, divididos em dois grupos de cinco. No primeiro grupo foi realizada uma incisão no 16º espaço intercostal esquerdo e posterior ressecção da 16ª costela. No segundo grupo a incisão foi feita sobre a 17ª costela com a remoção da mesma. Todas as estruturas identificadas foram registradas em fichas individuais, assim como a extensão exteriorizada do cólon transverso. Em todas os animais o cólon transverso foi totalmente visualizado e parcialmente exteriorizado, sendo que houve melhor manipulação e exteriorização no segundo grupo, além da maior facilidade no emprego da técnica, com a incisão sobre a costela a ser ressecada. Dessa forma, concluímos que o cólon transverso pode ser acessado pela fossa paralombar esquerda, sendo que a remoção da 17ª costela proporciona o melhor acesso para essa estrutura.

The transverse colon is a constriction of the bowel lumen, which canbe submitted to obstructive process. The knowledge enlargement about this structure and the adjacent ones has a great surgical importance. For such study, ten anatomic pieces, from equines corpses of different breed, age and sex, were used and divided in two groups. In the first group an incision was made in the left 16 intercostal space and farther resection of the 16 rib. In the second group an incision was made over the 17 rib, before its ressection. All the identified structures were registered into individual files, such as the extension of the exteriorized portion. In all of the studied pieces, the transverse colon was entirely visualized and partially exteriorized. However, we had better handling and exteriorization in the second group, as well as we noticed its technique was of easier execution. In accordance with the results, through this work is possible to conclude that the transverse colon can be approached by the left flank, and that the removal of the 17 rib provides a better access to the transverse colon.