Possibilidade de ossificação intracondral dirigida a partir de uma matriz óssea com titânio

In the present study, the relation between bone, cartilage and titanium was analyzed. According to the established methodology, homogeneous cartilage grafts conserved in alcohol 100 GL for 7 days were used, after the fixation of a homologous cartilage graft above the bone cortical of a rat femur (Rattus novergicus var. Albinus rodentia mammalia cepa Wistar), using a titanium screw implant. The animals were sacrificed at 10, 20, 30 and 60 days after surgery. To the histological examination, in hematoxillin and eosin sections, intrachondral bone neoformation could be observed since cortical surface, with possibility of complete substitution of the cartilage graft by bone, with similar volume and shape. In this experimental study we concluded that the homogeneous cartilage conserved can be used as graft not only for tissue substitution but also as an inductor of bone growth in rats.

Osteointegration of polylactide-based implants

Background. Materials degrading after implantation into bone are in the field of actual vision of orthopediс surgeon. These materials include polylactides, which are the ideal material for creating bone implants in 3D-printer, especially implants of complex shapes and different sizes. The purpose of the study is to conduct a comparative analysis of bone remodeling under conditions of implantation of polylactide 3D-printed screws into metadiaphyseal and diaphyseal defects of the rat femur. Materials and methods. Comparative analysis of bone remodeling under conditions of implantation of polylactide Ingeo™ Biopolymer 4032D 3D-printed screws into the metadiaphyseal and diaphyseal defects of the rat femur for 15, 30, 90, 180 and 270 days are conducted. After implantation of polylactide, areas of bone with implants were examined by the histological method with the determination of the osteointegration index. Results. It was found that for all the study periods the implants kept their shape, were surrounded by bone tissue. The osseointegration index on the 270th day in metadiaphyseal and diaphyseal defects is 97.1 and 94.3 %, respectively, and is statistically higher compared to the 15th day by 2.2 and 2.3 times (p < 0.001). Conclusions. The polylactide-based Ingeo™ Biopolymer 4032D implants are biocompatible, have high osteointegration qualities, do not cause inflammation in the surrounding soft tissues and bone marrow, do not lead to destructive changes of the bone in the implantation sites. At the end of the study (270 days), the degradation of polylactide is not found, which makes it possible to use it for fixation or filling cavities in compact and spongy bones for a long time.

Validation of a semiautomatic image analysis software for the quantification of musculoskeletal tissues

Background: Accurate quantification of bone, muscle, and their components is still an unmet need in the musculoskeletal field. Current methods to quantify tissue volumes in 3D images are expensive, labor-intensive, and time-consuming; thus, a reliable, valid, and quick application is highly needed.Methods: Tissue Compass is a standalone software for semiautomatic segmentation and automatic quantification of musculoskeletal organs. To validate the software, cross-sectional micro-CT scans images of rat femur (n=19), and CT images of hip and abdomen (n=100) from the Osteoporotic Fractures in Men (MrOS) Study were used to quantify bone, hematopoietic marrow (HBM), and marrow adipose tissue (MAT) using commercial manual software as a comparator. Also, abdominal CT scans (n=100) were used to quantify psoas muscle volumes and intermuscular adipose tissue (IMAT) using the same software. We calculated Pearson's correlation coefficients, individual intra-class correlation coefficients (ICC), and Bland-Altman limits of agreement together with Bland-Altman plots to show the inter- and intra-observer agreement between Tissue Compass and commercially available software.Results: In the animal study, the agreement between Tissue Compass and commercial software was r>0.93 and ICC>0.93 for rat femur measurements. Bland-Altman limits of agreement was -720.89 (-1.5e+04, 13074.00) for MAT, 4421.11 (-1.8e+04, 27149.73) for HBM and -6073.32 (-2.9e+04, 16388.37) for bone. The inter-observer agreement for QCT human study between two observers was r>0.99 and ICC>0.99. Bland-Altman limits of agreement was 0.01 (-0.07, 0.10) for MAT in hip, 0.02 (-0.08, 0.12) for HBM in hip, 0.05 (-0.15, 0.25) for bone in hip, 0.02 (-0.18, 0.22) for MAT in L1, 0.00 (-0.16, 0.16) for HBM in L1, 0.02 (-0.23, 0.27) for bone in L1. The intra-observer agreement for QCT human study between two applications was r>0.997 and ICC>0.99. Bland-Altman limits of agreement was 0.03 (-0.13, 0.20) for MAT in hip, 0.05 (-0.08, 0.18) for HBM in hip, 0.05 (-0.24, 0.34) for bone in hip, -0.02 (-0.34, 0.31) for MAT in L1, -0.14 (-0.44, 0.17) for HBM in L1, -0.29 (-0.62, 0.05) for bone in L1, 0.03 (-0.08, 0.15) for IMAT in psoas, and 0.02 (-0.35, 0.38) for muscle in psoas. Conclusion: Compared to a conventional application, Tissue Compass demonstrated high accuracy and non-inferiority while also facilitating easier analyses. Tissue Compass could become the tool of choice to diagnose tissue loss/gain syndromes in the future by requiring a small number of CT sections to detect tissue volumes and fat infiltration.

Improved osteogenesis in rat femur segmental defects treated with human allograft and zinc adjuvants

Bone allograft is widely used to treat large bone defects or complex fractures. However, processing methods can significantly compromise allograft osteogenic activity. Adjuvants that can restore the osteogenic activity of processed allograft should improve clinical outcomes. In this study, zinc was tested as an adjuvant to increase the osteogenic activity of human allograft in a Rag2 null rat femoral defect model. Femoral defects were treated with human demineralized bone matrix (DBM) mixed with carboxy methyl cellulose containing ZnCl2 (0, 75, 150, 300 µg) or Zn stearate (347 µg). Rat femur defects treated with DBM-ZnCl2 (75 µg) and DBM-Zn stearate (347 µg) showed increased calcified tissue in the defect site compared to DBM alone. Radiograph scoring and µCT (microcomputed tomography) analysis showed an increased amount of bone formation at the defects treated with DBM-Zn stearate. Use of zinc as an adjuvant was also tested using human cancellous bone chips. The bone chips were soaked in ZnCl2 solutions before being added to defect sites. Zn adsorbed onto the chips in a time- and concentration-dependent manner. Rat femur defects treated with Zn-bound bone chips had more new bone in the defects based on µCT and histomorphometric analyses. The results indicate that zinc supplementation of human bone allograft improves allograft osteogenic activity in the rat femur defect model.

Quantitative Evaluation of Osteocyte Morphology and Bone Anisotropic Extracellular Matrix in Rat Femur

Osteocytes are believed to play a crucial role in mechanosensation and mechanotransduction which are important for maintenance of mechanical integrity of bone. Recent investigations have revealed that the preferential orientation of bone extracellular matrix (ECM) mainly composed of collagen fibers and apatite crystallites is one of the important determinants of bone mechanical integrity. However, the relationship between osteocytes and ECM orientation remains unclear. In this study, the association between ECM orientation and anisotropy in the osteocyte lacuno-canalicular system, which is thought to be optimized along with the mechanical stimuli, was investigated using male rat femur. The degree of ECM orientation along the femur longitudinal axis was significantly and positively correlated with the anisotropic features of the osteocyte lacunae and canaliculi. At the femur middiaphysis, there are the osteocytes with lacunae that highly aligned along the bone long axis (principal stress direction) and canaliculi that preferentially extended perpendicular to the bone long axis, and the highest degree of apatite c-axis orientation along the bone long axis was shown. Based on these data, we propose a model in which osteocytes can change their lacuno-canalicular architecture depending on the mechanical environment so that they can become more susceptible to mechanical stimuli via fluid flow in the canalicular channel.