Analysis of fracture healing in osteopenic bone caused by disuse: experimental study

Osteoporosis has become a serious global public health issue. Hence, osteoporotic fracture healing has been investigated in several previous studies because there is still controversy over the effect osteoporosis has on the healing process. The current study aimed to analyze two different periods of bone healing in normal and osteopenic rats. Sixty, 7-week-old female Wistar rats were randomly divided into four groups: unrestricted and immobilized for 2 weeks after osteotomy (OU2), suspended and immobilized for 2 weeks after osteotomy (OS2), unrestricted and immobilized for 6 weeks after osteotomy (OU6), and suspended and immobilized for 6 weeks after osteotomy (OS6). Osteotomy was performed in the middle third of the right tibia 21 days after tail suspension, when the osteopenic condition was already set. The fractured limb was then immobilized by orthosis. Tibias were collected 2 and 6 weeks after osteotomy, and were analyzed by bone densitometry, mechanical testing, and histomorphometry. Bone mineral density values from bony calluses were significantly lower in the 2-week post-osteotomy groups compared with the 6-week post-osteotomy groups (multivariate general linear model analysis, P<0.000). Similarly, the mechanical properties showed that animals had stronger bones 6 weeks after osteotomy compared with 2 weeks after osteotomy (multivariate general linear model analysis, P<0.000). Histomorphometry indicated gradual bone healing. Results showed that osteopenia did not influence the bone healing process, and that time was an independent determinant factor regardless of whether the fracture was osteopenic. This suggests that the body is able to compensate for the negative effects of suspension.

Diabetes mellitus affects the biomechanical function of the callus and the expression of TGF-beta1 and BMP2 in an early stage of fracture healing

Transforming growth factor beta 1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2) are important regulators of bone repair and regeneration. In this study, we examined whether TGF-β1 and BMP-2 expressions were delayed during bone healing in type 1 diabetes mellitus. Tibial fractures were created in 95 diabetic and 95 control adult male Wistar rats of 10 weeks of age. At 1, 2, 3, 4, and 5 weeks after fracture induction, five rats were sacrificed from each group. The expressions of TGF-β1 and BMP2 in the fractured tibias were measured by immunohistochemistry and quantitative reverse-transcription polymerase chain reaction, weekly for the first 5 weeks post-fracture. Mechanical parameters (bending rigidity, torsional rigidity, destruction torque) of the healing bones were also assessed at 3, 4, and 5 weeks post-fracture, after the rats were sacrificed. The bending rigidity, torsional rigidity and destruction torque of the two groups increased continuously during the healing process. The diabetes group had lower mean values for bending rigidity, torsional rigidity and destruction torque compared with the control group (P<0.05). TGF-β1 and BMP-2 expression were significantly lower (P<0.05) in the control group than in the diabetes group at postoperative weeks 1, 2, and 3. Peak levels of TGF-β1 and BMP-2 expression were delayed by 1 week in the diabetes group compared with the control group. Our results demonstrate that there was a delayed recovery in the biomechanical function of the fractured bones in diabetic rats. This delay may be associated with a delayed expression of the growth factors TGF-β1 and BMP-2.

Mechanical properties of radial bone defects treated with autogenous graft covered with hydroxyapatite in rabbit / Propriedades mecânicas de defeito de osso radial tratado com enxerto autógeno coberto com nano-hydroxyapatite em coelho

PURPOSE: To determine biomechanical property of autogenous bone graft covered with hydroxyapatite in the defect of radial bone in rabbit. METHODS: Eighteen adult male New Zealand white rabbits were used which were divided into three groups (I, II, III) of six rabbits each. A segmental bone defect of 10 mm in length was created in the middle of the right radial shaft under general effective anesthesia in all rabbits and were stabilized using mini-plate with four screws. The defects In group I were left as such without filler, whereas in group II the defect were filled up with harvested 10 mm rib bone and in group III the defect were packed with rib bone covered with nano-hydroxyapatite. All rabbits in three groups were divided into two subgroups (one month and three months duration with three rabbits in each one). RESULTS: The mechanical property and the mean load for fracturing normal radial bone was recorded 388.2±6 N whereas it was 72.4±12.8 N for group I in 1 month duration which was recorded 182.4±14.2 N for group II and 211.6±10.4 N for group III at the end of 1 month. These values were 97.6±10.2 N for group I and 324.6±8.2 N for group II and 372.6±17.4 N for group III at the end of three months after implantation. CONCLUSION: Implantation of autologous graft covered with hydroxyapatite indicated to have positive effect in integral formation of qualitative callus at the site of fracture and early re-organization of callus to regain mechanical strength too.

OBJETIVO: Determinar as propriedades biomecânicas de enxerto ósseo autógeno coberto com hidroxiapatita em defeito do osso radial em coelhos. MÉTODOS: Foram utilizados 18 coelhos adultos, machos, brancos, Nova Zelândia, distribuídos em três grupos (I, II, III) de seis coelhos cada. Um defeito segmentar de 10 mm de comprimento foi criado no meio do eixo radial direito sob anestesia geral efetiva em todos os coelhos e foram fixados usando mini-placa com quatro parafusos. Os defeitos no grupo I foram deixados sem preenchimento, enquanto no grupo II o defeito foi preenchido com 10 mm de costela recoberta com nano-hidroxiapatita. Os coelhos nos três grupos foram distribuídos em dois subgrupos (Um e três meses, com três coelhos cada um). RESULTADOS: A propriedade mecânica e a média do peso para fraturar o osso radial normal foi 388,2±6 N, enquanto para o Grupo I, com um mês foi 72,4±12,8 N, para o grupo II 182,4±14,2 N e para o Grupo III 211,6±10,4 N. Após três meses de implantação, os valores foram 97,6±10,2 N para o Grupo I, 324,6±8,2 N para o Grupo II e 372,6±17,4 N para o Grupo III. CONCLUSÃO: A implantação de enxerto autólogo recoberto com hidroxiapatita indicou ter um efeito positivo na formação integral qualitativa do calo ósseo no local da fratura e precoce reorganização do calo com recuperação da força mecânica.

Resposta osteogênica sistêmica no estímulo medular ósseo / Osteogenic systemic response at bone marrow stimulation

OBJETIVO: Avaliar a influência da resposta osteogênica sistêmica, causada pelo estímulo da medula óssea à distância, na consolidação de falha óssea. MÉTODO: 36 coelhos adultos jovens foram divididos aleatoriamente em três grupos (A, B, C) e submetidos à ostectomia do rádio direito, com retirada de 4mm de fragmento ósseo. Os animais do grupo A foram submetidos ao estímulo da medula óssea pela sua ablação do fêmur esquerdo. Os animais do grupo B foram submetidos ao estímulo da medula óssea pela introdução de fio de Kirschner com 1,5mm de espessura, no interior do canal medular femoral esquerdo. Os animais do grupo C foram utilizados como grupo controle. Foram realizadas radiografias semanais até a 4ª semana pós-operatória, quando os animais foram sacrificados. Foi realizado estudo histomorfométrico do calo ósseo formado no local da ostectomia. As radiografias foram avaliadas para análise da evolução da consolidação óssea. RESULTADOS: Os grupos que sofreram estímulo medular à distância tiveram menor número de células ósseas, comparativamente ao grupo controle. No estudo radiográfico não houve diferença na evolução da consolidação entre os grupos. CONCLUSÃO: O estímulo da medula óssea à distância influenciou desfavoravelmente a consolidação de falha óssea em coelhos.

OBJECTIVE: To assess the influence of systemic osteogenic response caused by remote stimulation of bone marrow in a bone gap union. METHOD: 36 young adult rabbits were employed. The animals were randomly divided into 3 groups (A, B, C) and submitted to ostectomy of the right radius, removing 4mm of bone. The animals on Group A had their bone marrow stimulated by ablation on the left femur. Animals on Group B had their bone marrow stimulated by introducing a 1.5mm-thick Kirschner wire into the shaft of the left femur. The animals on Group C served as controls. X-ray images were taken on a weekly basis until the 4th post-surgical week, when the animals were sacrificed. Histomorphometric study of the bony callus formed at the ostectomy site was conducted. The x-ray images were evaluated in order to analyze the evolution of bone union at the ostectomy site. RESULTS: The groups with remote bone marrow stimulation had a smaller number of bone cells as compared to the control group. On radiographic studies, no difference in terms of evolution of union was evident between the groups. CONCLUSION: Remote stimulation of bone marrow had an unfavorable influence on bone gap union in rabbits.

O uso do aspirado de medula óssea de ilíaco em falhas ósseas de fêmures de camundongos: estudo experimental / The use of inhaled bone marrow of ileum in bone failures of femurs of rats: experimental study

Os autores estudam a utilizacão de medula óssea em camundongos como estimulacão da formacão de calo ósseo. Foram utilizados dez camundongos adultos machos de linhagem isogênica gioto com peso de aproximadamente 250 gramas, e realizadas falhas ósseas na região distal do fêmur com alternância do lado direito e esquerdo, divididos em grupos A e B, sendo como controle camundongos com falha óssea isolado e com falhas ósseas com medula óssea colhida previamente de cada camundongo. Após análise qualitativa e quantitativa foi observado que o uso do aspirado de medula óssea não leva à estimulacão da formacão do calo ósseo e não há o aumento de processo inflamatório local.

Efeitos da desnervaçäo periférica sobre a formaçäo do calo ósseo: estudo experimental em ratos / Effects of the peripheral denervation on fracture healing: experimental study in rats

Foi feito estudo experimental em 24 ratos de raça Wistar, com 30 dias de vida. Foram produzidas fraturas fechadas na diáfise dos metatarsais de ambas as patas, ao mesmo tempo em que se procedeu à neurectomia ciática esquerda, ao nível de regiäo glútea. O processo de consolidaçäo das fraturas foi analisado através de estudo histológico nas 1ª, 2ª, 3ª e 6ª semanas após a produçäo da fratura, comparando-se o lado desnervado com o contralateral. A desnervaçäo ciática nao resultou em alteraçöes no processo de formaçäo do calo ósseo.