The present study aimed to evaluate the mechanical and degradative properties of poly(L-co-D,L-lactic acid)/silicate bioactive glass fibers (PLDLA/SGFs) composite pins in vivo. Both PLDLA and PLDLA/SGFs pins were inserted into the erector spinae muscles and femurs of beagle dogs and were harvested 6, 12, 16, 26, 52, 78, and 104 weeks after insertion. Bone formation around the pins was evaluated by micro-computed tomography. Mechanical properties were measured by the shear strength test. Thermogravimetric analysis, differential scanning calorimetry, and gel permeation chromatography were used to assess the degradation of these materials. The surface and cross-sectional morphology of both pins were observed using a scanning electron microscope. The experimental data demonstrated that PLDLA/SGFs pins can support new bone formation due to the influence of bioactive glass fibers. PLDLA/SGFs composite pins had higher initial shear strength and were relatively stable for at least 26 weeks. The addition of bioactive glass fibers accelerated the degradation rate of the composite pins. Thus, PLDLA/SGFs composite pins have promising potential for bone fixation applications.

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The purpose of this two-year study was to evaluate the histocompatibility and osteogenic properties of a composite material consisting of poly(l- co-d,l lactide) (PLDLA) and silica-based bioactive glass fibers in vivo. PLDLA and PLDLA/silica-based bioactive glass fibers pins were implanted into the erector spinae muscles and femurs of beagles. Muscle and bone tissue samples were harvested 6, 12, 16, 26, 52, 78, and 104 weeks after implantation. Histology analysis was used to assess the histocompatibility, angiogenesis, and bone-implant contact. Micro-computed tomography was used to evaluate bone formation around the pins. Immunohistochemistry and western blotting revealed the expression level of the osteogenesis-related proteins. Addition of bioactive glass was demonstrated to possess better histocompatibility and reduce the inflammatory reactions in vivo. Moreover, PLDLA/silica-based bioactive glass fibers pins were demonstrated to promote angiogenesis and increase osteogenesis-related proteins expression, and thus played a positive role in osteogenesis and osseointegration after implantation. Our findings indicated that a composite of PLDLA and silica-based bioactive glass fiber is a promising biodegradable material for clinical use.

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