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.
Often fractures of long bones in horses are comminuted and form bone gaps, which represent a major challenge for the fixation of these fractures by loss of contact between the fragments. Bone grafts help in treating this kind of fracture and synthetic
Purpose: To compare biomechanical characteristics at different regions of the equine third metacarpal bone using standardized test specimens. Methods: Standardized test specimens were made from samples collected from each third metacarpal bone. Cortical bone samples were collected from the lateral (ts4L) and medial (ts4M) cortices of the mid-diaphysis and trabecular bone samples were collected from the distal (ts3) and proximal (ts2) epiphyses. A sample corresponding to the mid third of the third metacarpal bone was also collected (ts1). Test specimens were submitted to compressive testing for determination and comparison of biomechanical properties. Results: Stress and modulus of elasticity of ts4L and ts4M did not differ at the time of fracture. However, the modulus of elasticity of ts4L and ts4M differed from ts1. Maximum tension and modulus of elasticity differed between ts2 and ts3. A medium to high positive correlation between test specimen density and bone biomechanical properties was observed. Conclusion: The lateral and medial cortices of the equine third metacarpal bone have similar biomechanical characteristics. The proximal and distal epiphyses of the equine third metacarpal bone have different biomechanical properties that are correlated with bone density in these regions.
decreased from 2260.64µd to 320.25µd and from 2260.64µd to 89.88µd following filling of the bone defect with RCP or CPC-chitosan composite respectively. Bone deformation around the defect increased following treatment with RCP or CPCchitosan composite. However bone deformation away from the defect remained unchanged. Maximum load within the elastic limit increased from 1008N to 8804N when the experimental defect was filled with chitosan composite. Conversely, construct deformation within the elastic limit decreased from 1.64mm to 1.26mm following treatment with RCP. Maximum load to construct failure increased from 1660N to 15187N and 11012N following bone defect repair with RCP or calcium phosphate cement-chitosan composite respectively. However, construct maximum deformation decreased from 5.4mm to 2.16mm when calcium phosphate cementchitosan composite was used.
Bone properties determined by biomechanical testing are extremely important for both metallic implants and osteosyntesis protocols development. The objective of this study was determining the biomechanical properties of some different regions of third metacarpal bone submitted to compression and bending tensions, using thirty pairs divided into two groups, each group formed by one limb of each pair. During the three points bending test the dorsal surface of the entire bone was placed upon two cylindrical bases 150 mm far from each one, and load was applied in the mid point on the palmar aspect of the bone, 75 mm far from each cylindrical base, until bone's failure. For the compression test samples of different bone regions were used. The mid diaphysis was used as samples (cp1), which its height was twice its latero-lateral thickness at the mid point of the bone length. All cp1 were submitted to proximodistal compressive loads until it reached 4000kgf. Using a trefina the others samples were obtained from the fragments of bone not used for the cp1 confection. Two of them were collected from the trabecular portion of proximal (cp2) and distal (cp3) epiphysis, and the others from lateral (cp4L) and medial (cp4m) cortex region of diaphysis. All of them were submitted to proximo-distal compressive load until their failure. By the analysis of the results obtained was concluded that the medial cortex is more resistant to tensions and has greater elastic modulus than the medial cortex, at the diaphyseal region; the trabecular bone at the distal epiphysis has the same elastic modulus than at the proximal epiphysis, however its failures occurs at greater loads.
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