Assessment Of Bone Repair Research Articles

Effect of micro-CT acquisition parameters and individual analysis on the assessment of bone repair.

This study aimed to investigate whether two acquisition parameters, voxel size and filter thickness, used in a micro-computed tomography (micro-CT) scan, together with the examiner's experience, influence the outcome of bone repair analysis in an experimental model. Bone defects were created in rat tibiae and scanned using two voxel sizes of 6- or 12-µm and two aluminum filter thickness of 0.5- or 1-mm. Then, bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) were analyzed twice by two groups of operators: experienced and inexperienced examiners. For BV/TV, no significant differences were found between scanning voxel sizes of 6 and 12 µm for the experienced examiners; however, for the inexperienced examiners, the analysis performed using a 12-µm voxel size resulted in higher BV/TV values (32.4 and 32.9) than those acquired using a 6-µm voxel size (25.4 and 24.8) (p < 0.05). For Tb.Th, no significant differences between the analyses performed by experienced and inexperienced groups were observed when using the 6-µm voxel size. However, inexperienced examiners' analysis revealed higher Tb.Th values when using the 12-µm voxel size compared with 6 µm (0.05 vs. 0.03, p < 0.05). Filter thickness had no influence on the results of any group. In conclusion, voxel size and operator experience affected the measured Tb.Th and BV/TV of a region with new bone formation. Operator experience in micro-CT analysis is more critical for BV/TV than for Tb.Th, whereas voxel size significantly affects Tb.Th evaluation. Operators in the initial phases of research training should be calibrated for bone assessments.

Drill Hole Models to Investigate Bone Repair.

Our understanding of the mechanisms underlying fracture healing is rapidly developing and is contributing to new therapeutic strategies to enhance repair. To gain new insights, animal models must also evolve. From initially imprecise, uncontrolled bone defects we now have precise injury models that still capture all of the stages and phases of bone repair yet do so in a highly reproducible manner. The simple mono-cortical defect model allows assessment of bone repair through a cartilage intermediate, e.g., endochondral ossification, as well as direct bone repair, e.g., intramembranous healing. Cellular contributions of the periosteum can be distinguished from contributions originating in the bone marrow. In this chapter, we focus on the advantages of this bone repair model, as well as its limitations.

Impaired bone quality characterized by apatite orientation under stress shielding following fixing of a fracture of the radius with a 3D printed Ti-6Al-4V custom-made bone plate in dogs

Custom-made implants have recently gained attention in veterinary medicine because of their ability to properly fit animal bones having a wide variety of shapes and sizes. The effect of custom-made implants on bone soundness and the regeneration process is not yet clear. We fabricated a 3D printed Ti-6Al-4V custom-made bone plate that fits the shape of the dog radius, and placed it into the radius where an osteotomy had been made. The preferential orientation of the apatite c-axis contributes to the mechanical integrity of the bone and is a reliable measure of bone quality. We determined this parameter as well as the bone shape and bone mineral density (BMD). The bone portion which lies parallel to the bone plate exhibited bone resorption, decreased BMD, and significant degradation of apatite orientation, relative to the portion outside the plate, at 7 months after the operation. This demonstrates the presence of stress shielding in which applied stress is not transmitted to bone due to the insertion of a stiff bone plate. This reduced stress condition clearly influences the bone regeneration process. The apatite orientation in the regenerated site remained different even after 7 months of regeneration, indicating insufficient mechanical function in the regenerated portion. This is the first study in which the apatite orientation and BMD of the radius were evaluated under conditions of stress shielding in dogs. Our results suggest that assessment of bone repair by radiography can indicate the degree of restoration of BMD, but not the apatite orientation.

Assessment of bone repair in critical-size defect in the calvarium of rats after the implantation of tricalcium phosphate beta (β-TCP)

ObjectivesEvaluating the osteoconductive property of tricalcium phosphate beta (β-TCP) in comparison to that of inorganic bovine bone for repair in a critical-size defect in the rat calvarium.Materials and MethodsCritical-size defects of 7mm were made with a trephine in the calvaria of 48 Wistar rats. The animals were divided into four groups, and the defects in each group were filled with tricalcium phosphate beta (β-TCP), inorganic bovine bone (Bio-Oss), autogenous bone, or left empty. The animals were euthanized at two different time points (30 and 60days post-operation). All defects were recovered with a absorbable membrane of bovine cortical bone. Histological, histometric, and immunohistochemical (osteocalcin) assessments were carried out at 30 and 60days post-operation. ResultsAt 30days post-operation, all groups showed areas of bone formation, predominantly when autogenous grafts were used. However, there were no statistically significant differences between the treatment groups (p>0.05). After 60days, there were similarities in the bone formation patterns between the β-TCP (26.32±) and Bio-Oss (17.35±) groups (p=0.549). In terms of the immunohistochemical assessment of osteocalcin, the clot group showed light to moderate staining at 30 and 60days. The autogenous group showed moderate staining at 30days and moderate to intense staining after 60days. The Bio-Oss group showed light to moderate staining after 30days and intense staining at 60days. The β-TCP group showed moderate staining at 30 and 60days post-operation. Conclusionβ-TCP is a good osteoconductive material with similar effects to those of inorganic bovine bone graft and is suitable for utilization in the repair of bone defects.

Avaliação do reparo ósseo por microtomografia por raio-X

A microtomografia 3D por raio-X proporciona medidas quantitativas e tridimensionais da estrutura do calo e essas medidas podem potencialmente estar relacionadas com a resistência do calo. A avaliação quantitativa do reparo ósseo por meio de novas metodologias tem importante aplicação nas pesquisas experimentais relacionadas a tecnologias invasivas e não invasivas para a estimulação do mesmo. O objetivo desse estudo foi avaliar o reparo ósseo por meio da μCT em defeito ósseo em fêmur de rato. Trinta ratos machos da classe Wistar com peso médio de 300g foram divididos em grupos experimentais de 10 animais em cada grupo. Os animais foram anestesiados e um furo com 1,2mm de diâmetro foi realizada na porção medial do fêmur utilizando-se uma broca odontológica. No 7º, 14º e 21º pós-cirúrgico, os animais dos grupos experimentais 1, 2 e 3, respectivamente, foram sacrificados e o fêmur esquerdo excisado. Os fêmures foram envolvidos em gaze e mergulhas em solução PBS e armazenados em um saco plástico em freezer a -20º até a análise microtomográfica. Os fêmures foram escaneados pelo microtomógrafo 1172 (SkyScan, Bélgica). Os softwares NRecon, Dataviewer, CT-Analyzer and CT-Vol, fornecidos pelo fabricante do microtomógrafo, foram utilizados para as seguinte análises: a) análise visual das reconstruções microtomográficas dos fêmures através de secções transversais, coronais e sagitais; b) segmentação do calo ósseo nas reconstruções através de algoritmo de processamento de imagem para quantificação dos parâmetros volume total do calo ósseo (TV), volume do calo ósseo mineralizado (BV), relação BV/TV e densidade mineral óssea volumétrica do calo ósseo (BMD); c) visualização 3D do calo ósseo. A análise estatística dos parâmetros medidos utilizou o teste t de Student com um nível de significância p &lt; 0,05. Houve um aumento estatisticamente significante nos valores dos parâmetros BV/TV e BMD na comparação entre os grupos experimentais 1 e 2. A comparação entre os grupos 3 e 4 não apresentou significância estatística. Os resultados são coerentes com dados encontrados na literatura sobre a fisiologia óssea, porém o algoritmo de processamento de imagem utilizado necessita aprimoramento em alguns de seus procedimentos para se obter melhor resultado de segmentação do calo ósseo na região de interesse

Assessment of bone repair following the use of inorganic bone graft Gen-ox ®Inorganic and membrane associated or not with 830-nm laser light

Assessment of bone repair following the use of inorganic bone graft Gen-ox ®Inorganic and membrane associated or not with 830-nm laser light