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Background: Whether polycystic ovary syndrome (PCOS) affects bone health during a woman's lifespan remains controversial. An androgenized rodent model replicated many metabolic and reproductive features of women with PCOS, and we aimed to use it to investigate the impact of androgens on microarchitecture (by micro-CT), bone mechanical strength, bone formation and resorption markers in rats with intact ovaries (SHAM) who underwent oophorectomy. Methods: Wistar rats (Rattus norvegicus albinus) were employed for the experiments in this study. The protocol of androgenization consisted of the application of 1.25 mg s.c. testosterone propionate beteween days 2-5 of life, while the controls received the same amount of corn oil s.c. as previously established. Androgenized SHAM rats exhibited chronic anovulation identified by vaginal cytology and a reduction in the proportion of corpus luteum in the ovary in comparison to control SHAM rats. The realization of the ovariectomy or SHAM procedure occurred on Day 100 of life. All groups (n = 8) were followed-up for 180 days to address the study endpoints. Results: Micro-CT from androgenized female rats (SHAM) showed a divergence between the trabecular and cortical bone profiles. Compared to SHAM controls, these rats had an increase in trabecular bone mass with a diminution in bone resorption C-terminal telopeptide of type 1 collagen (CTX) (p < 0.05), a concomitant decrease in cortical area and thickness in the femur, and a reduction in the strength of the femur on the mechanical test (p < 0.01). Conclusions: Our results suggest that a reduction in the cortical thickness and cortical area observed in PCOS model rats was associated with a reduced strength of the femur, despite increased trabecular formation. Ovariectomy in the androgenized OVX group limited the progression rate of cortical bone loss, resulting in bone resistance and cortical thickness comparable to those observed in the control OVX group.

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Bone fractures cause acute inflammation that, despite being important for initial repair, may delay the healing of the damaged bone. Parenteral injection of dietary protein has been shown to decrease inflammation and accelerate the repair of skin wounds and other inflammatory pathologies. Thus, our aim was to evaluate whether the intraperitoneal (i.p.) immunization with zein, an abundant protein in rodent chow, would favor bone healing. Wistar rats received i.p. immunization: saline (SG), adjuvant (AG) and zein associated with adjuvant (ZG). Then, a 2 mm of defect bone was performed on the right tibia, and on days 7, 14, 28 and 45 thereafter, analyses were performed. The results showed that the injection of zein reduced inflammation without impairing bone mineralization. Moreover, biomechanical tests demonstrated higher levels of maximum force (N) in ZG, indicating better mechanical resistance in relation to the others. The computerized tomography also indicated lower levels of medullary content in the ZG than in the SG, suggesting the absence of trabeculae in the medullary region in the ZG. These findings suggest that the injection of zein in previously tolerated animals may improve bone repair, leading to mechanically functional bone formation.

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The treatment of bone regeneration failures has been constantly improved with the study of new biomaterials. Techgraft® is a collagen membrane derived from bovine pericardium, which has been shown to have biocompatibility and effectiveness in tissue repair. However, its use in orthopedics has not yet been evaluated. Therefore, the purpose of this study was to characterize a bovine pericardium collagen membrane and evaluate the effects of its use in the regeneration of a bone defect in rat tibia. Scanning electron microscopy, atomic force microscopy, weight lost and water uptake tests, and mechanical test were performed. Afterwards, the membrane was tested in an experimental study, using 12 male Sprague Dawley rats. A bone defect was surgically made in tibiae of animals, which were assigned to two groups (n = 6): bone defect treated with collagen membrane (TG) and bone defect without treatment (CONT). Then, tibiae were submitted to micro-CT. The membranes preserved their natural collagen characteristics, presenting great strength, high water absorption, hydrophilicity, and almost complete dissolution in 30 days. In the experimental study, the membrane enhanced the growth of bone tissue in contact with its surface. A higher bone volume and trabeculae number and less trabecular space was observed in bone defects of the membrane group compared to the control group at 21 days. In conclusion, the Techgraft membrane seems to have favorable characteristics for treatment of long bone repair.

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Cervical arthroplasty with disc prosthesis has been proposed as a treatment option for dogs with Cervical Spondylomyelopathy. The present study developed a novel vertebral disc prosthesis for dogs. Sixteen Functional Spinal Units (C5-C6) were collected from dog cadavers with body weights ranging between 25 and 35 kg, and their vertebral measurements were used to design a prosthetic disc. The sizing of the prosthesis was performed based on the averages of the measurements of width, height, and length of the vertebral bodies from C5-C6 of all specimens. The prosthesis was developed using the Rhinoceros 3D® and SolidWorks® programs, and 3D prototyping was carried out to define the best design. The developed prosthesis consisted of two independent parts that are fixed to the cranial and caudal vertebral bodies, in the intervertebral space, and fitted together by metal-to-metal surfaces capable of moving in the lateral, ventral, and dorsal directions. Each part of the prosthesis is angled in two portions: vertically, in the intervertebral space, and horizontally, in contact with the ventral surface of the vertebral bodies, both of which are fixed by means of monocortical locking screws. The design of the developed prototype allowed a good fit in the intervertebral space between C4-C5, C5-C6, and C6-C7.

A artroplastia cervical com prótese de disco tem sido proposta como uma opção de tratamento para cães com Espondilomielopatia Cervical. O presente estudo teve como objetivo desenvolver uma nova prótese de disco intervertebral para cães. Dezesseis Unidades Funcionais de Coluna Vertebral (C5-C6) foram coletadas de cadáveres de cães com peso corporal variando entre 25 e 35 kg, e suas medidas vertebrais foram usadas para projetar um disco intervertebral protético. O dimensionamento da prótese foi realizado com base nas médias das mensurações da largura, altura e comprimento dos corpos vertebrais de C5-C6 de todos os espécimes. A prótese foi desenvolvida nos programas Rhinoceros 3D® e SolidWorks® e utilizou-se prototipagem em 3D para a definição do melhor design. A prótese desenvolvida é formada por duas partes independentes que se fixam às espífises dos corpos vertebrais cranial e caudalmente ao espaço intervertebral, e se encaixam entre si por superfícies de metal-metal com capacidade de movimentação nas direções lateral, ventral e dorsal. Cada parte da prótese é angulada em duas porções: a vertical, que fica no espaço intervertebral, e a horizontal, que fica em contato com a superfície ventral dos corpos vertebrais, ambas as quais são fixadas por meio de parafusos bloqueados monocorticais. O design do protótipo desenvolvido permitiu bom encaixe no espaço intervertebral entre C4-C5, C5-C6 e C6-C7.

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ABSTRACT: Cervical spondylomyelopathy (CSM) is a disease that affects mostly large- and giant-breed dogs. It is characterized by abnormalities of the cervical spine that may cause damage to the spinal cord and nerve roots. Cervical disc arthroplasty has been proposed as a treatment option in veterinary medicine. The current study evaluated the main stresses in a novel canine vertebral disc prosthesis and vertebral bodies using finite element analysis. Two experimental groups were created based on the material used for the prosthesis: stainless steel group (SSG) and titanium alloy group (TAG). Vertebral and prosthetic average equivalents von-Mises stress (VMS) and minimum principal stress (MiPS) were assessed while compressive, tensile, and lateral bending shear loads were applied. The stainless steel group had greater VMS distribution on all the evaluated parameters while the titanium alloy group had greater MiPS. Stresses were more concentrated on the lateral and ventral surfaces of the vertebral bodies than on their endplates. The average prosthetic stresses were more concentrated on the bone/implant contact surface than on the prosthesis/screw interface. Maximum stresses were concentrated in the screws' cranial surface. The novel prosthesis allows even distribution along the vertebral body. Comparing prosthesis materials, titanium alloy was marginally superior regarding average stresses in all directions and should be less likely to suffer subsidence.

RESUMO: Espondilomielopatia cervical (EMC) é uma doença que geralmente afeta cães de raças grandes e gigantes. Ela é caracterizada por anormalidades da coluna cervical que podem causar danos à medula espinhal ou às raízes nervosas. Artroplastia cervical com prótese de disco tem sido proposta como opção de tratamento na medicina veterinária. O presente estudo teve como objetivo avaliar os principais estresses em uma nova prótese de disco intervertebral canina e corpos vertebrais por meio da análise de elementos finitos. Foram compostos dois grupos experimentais que representaram o material constituinte da nova prótese: grupos aço inoxidável (SSG) e o liga de titânio (TAG). Tensões equivalente de von-Mises (VMS) e tensão principal mínima (MiPS) média foram avaliadas sob forças de compressão, tração e torção para vértebras e prótese. O grupo SSG teve maior distribuição de VMS para todos parâmetros avaliados, enquanto o grupo TAG teve maior MiPS. Estresses estiveram mais concentrados nas superfícies lateral e ventral dos corpos vertebrais do que nas placas terminais. Os estresses médios da prótese foram mais concentrados na superfície de contato osso/implante do que na interface prótese/parafuso. Estresses máximos foram concentrados na superfície cranial do parafuso. A nova prótese permitiu distribuição uniforme do estresse ao longo do corpo vertebral. Comparando os materiais da prótese, a liga de titânio foi marginalmente superior quanto aos estresses médios em todas as direções, sendo menos provável que sofra afundamento da prótese.

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Cervical spondylomyelopathy (CSM) is a disease that affects mostly large- and giant-breed dogs. It is characterized by abnormalities of the cervical spine that may cause damage to the spinal cord and nerve roots. Cervical disc arthroplasty has been proposed as a treatment option in veterinary medicine. The current study evaluated the main stresses in a novel canine vertebral disc prosthesis and vertebral bodies using finite element analysis. Two experimental groups were created based on the material used for the prosthesis: stainless steel group (SSG) and titanium alloy group (TAG). Vertebral and prosthetic average equivalents von-Mises stress (VMS) and minimum principal stress (MiPS) were assessed while compressive, tensile, and lateral bending shear loads were applied. The stainless steel group had greater VMS distribution on all the evaluated parameters while the titanium alloy group had greater MiPS. Stresses were more concentrated on the lateral and ventral surfaces of the vertebral bodies than on their endplates. The average prosthetic stresses were more concentrated on the bone/implant contact surface than on the prosthesis/screw interface. Maximum stresses were concentrated in the screws' cranial surface. The novel prosthesis allows even distribution along the vertebral body. Comparing prosthesis materials, titanium alloy was marginally superior regarding average stresses in all directions and should be less likely to suffer subsidence.

Espondilomielopatia cervical (EMC) é uma doença que geralmente afeta cães de raças grandes e gigantes. Ela é caracterizada por anormalidades da coluna cervical que podem causar danos à medula espinhal ou às raízes nervosas. Artroplastia cervical com prótese de disco tem sido proposta como opção de tratamento na medicina veterinária. O presente estudo teve como objetivo avaliar os principais estresses em uma nova prótese de disco intervertebral canina e corpos vertebrais por meio da análise de elementos finitos. Foram compostos dois grupos experimentais que representaram o material constituinte da nova prótese: grupos aço inoxidável (SSG) e o liga de titânio (TAG). Tensões equivalente de von-Mises (VMS) e tensão principal mínima (MiPS) média foram avaliadas sob forças de compressão, tração e torção para vértebras e prótese. O grupo SSG teve maior distribuição de VMS para todos parâmetros avaliados, enquanto o grupo TAG teve maior MiPS. Estresses estiveram mais concentrados nas superfícies lateral e ventral dos corpos vertebrais do que nas placas terminais. Os estresses médios da prótese foram mais concentrados na superfície de contato osso/implante do que na interface prótese/parafuso. Estresses máximos foram concentrados na superfície cranial do parafuso. A nova prótese permitiu distribuição uniforme do estresse ao longo do corpo vertebral. Comparando os materiais da prótese, a liga de titânio foi marginalmente superior quanto aos estresses médios em todas as direções, sendo menos provável que sofra afundamento da prótese.

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Objective We aimed to study the "in vitro" pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw, SpineGuard Inc, Boulder, Colorado, USA), a screw designed to be inserted using a direct insertion technique. Methods Dynamic Surgical Guidance Screws of 5.5 and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16g/cm 3 ). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. Results Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared with line-to-line tapping. Conclusion Dynamic Surgical Guidance Screw showed the highest pullout strength after its insertion without pilot hole and tapping.

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Abstract Objective We aimed to study the "in vitro" pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw, SpineGuard Inc, Boulder, Colorado, USA), a screw designed to be inserted using a direct insertion technique. Methods Dynamic Surgical Guidance Screws of 5.5 and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16g/cm3). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. Results Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared with lineto-line tapping. Conclusion Dynamic Surgical Guidance Screw showed the highest pullout strength after its insertion without pilot hole and tapping.

Resumo Objetivo Nosso objetivo foi estudar a resistência à extração "in vitro" do parafuso SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct (Parafuso DSG Guia Cirúrgico Dinâmico, SpineGuard Inc, Boulder, Colorado, USA), um parafuso projetado para ser inserido utilizando a técnica de inserção direta. Métodos Os parafusos DSG de 5,5 e 6,5 mm foram introduzidos em blocos de poliuretano com densidade de 10 PCF (0,16g/cm3). De acordo com o grupo experimental, os parafusos foram inseridos sem um orifício piloto, com um orifício piloto sem o macheamento, com macheamento e com macheamento linha a linha. Os testes de extração do parafuso foram realizados em uma máquina de teste universal, após a inserção do parafuso em blocos de poliuretano. Resultados Os parafusos inseridos diretamente nos blocos de poliuretano sem o orifício piloto e o macheamento mostraram uma resistência à extração estatisticamente maior. A inserção do parafuso sem o macheamento ou com o macho de menor diâmetro aumenta a resistência à extração do parafuso em comparação com o macheamento linha a linha. Conclusão O parafuso DSG apresentou a maior resistência à extração após a inserção sem o orifício piloto e o macheamento.

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Objective To evaluate, through a biomechanical assay, the maximum load, energy, and displacement necessary for the occurrence of fractures in synthetic models of femurs after the removal of cannulated screws and the performance of a reinforcement technique with polymethylmethacrylate (PMMA) in different combined positions. Methods In total, 25 synthetic bones were used, and they were divided into 4 groups: the control group (CG), with 10 models without perforation, and the test groups (A, B and C), with 5 models each. The test groups were fixed with cannulated screws using the Asnis technique, and they had the synthesis removed, and two of the holes formed by the reinforcement technique with PMMA were filled. The biomechanical analysis was performed simulating a fall on the large trochanter using a servo-hydraulic machine. Results All specimens of the CG and of groups A, B and C presented basal-cervical fracture of the femoral neck, except for a single model in group B, which presented a longitudinal fracture. An average of 5.4 mL of PMMA were used to reinforce the groups with filling. According to the analysis of variance (ANOVA) and the Tukey multiple comparison test, at the level of 5%, we observed that the CG presented significant differences in relation to groups A and C in the following parameters: maximum load, energy up to the fracture, and displacement. Conclusion We observed that groups A and C, when compared to the CG, showed significant differences in the observation of displacement, maximum load, and energy until the fracture.

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OBJECTIVE: Study the in vitro pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw), a screw pedicle designed to be inserted using a direct insertion technique. METHODS: DSG Screws of 5.5 mm and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16 g/cm3). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. RESULTS: Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared to line-to-line tapping. CONCLUSION: DSG Screw showed the highest pullout strength after its insertion without pilot hole and tapping. Level of Evidence V, Expert Opinion.

OBJETIVO: Estudar a resistência ao arrancamento in vitro do parafuso de inserção direta da SpineGuard/Zavation (parafuso DSG), um parafuso pedicular projetado para ser inserido usando a técnica de inserção direta. MÉTODOS: Parafusos DSG de 5,5 mm e 6,5 mm foram introduzidos em blocos de poliuretano com densidade de 10 PCF (0,16 g/cm3). De acordo com o grupo experimental, os parafusos foram inseridos sem orifício piloto, com orifício e sem macheamento e macheamento diâmetro inferior com mesma geometria. Os testes de resistência dos parafusos foram realizados usando uma máquina de teste universal após a inserção dos parafusos nos blocos de poliuretano. RESULTADOS: Os parafusos inseridos diretamente nos blocos de poliuretano sem orifício piloto e sem macheamento apresentaram uma resistência de arrancamento com significância estatística maior. A inserção do parafuso sem macheamento ou com macheamento com diâmetro inferior apresenta maior resistência ao arrancamento em comparação com o macheamento do mesmo diâmetro. CONCLUSÃO: O parafuso DSG apresentou a maior resistência ao arrancamento após sua inserção sem orifício piloto e sem macheamento. Nível de Evidência V, Opinião do Especialista.

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ABSTRACT Objective: Study the in vitro pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw), a screw pedicle designed to be inserted using a direct insertion technique. Methods: DSG Screws of 5.5 mm and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16 g/cm3). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. Results: Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared to line-to-line tapping. Conclusion: DSG Screw showed the highest pullout strength after its insertion without pilot hole and tapping. Level of Evidence V, Expert Opinion.

RESUMO Objetivo: Estudar a resistência ao arrancamento in vitro do parafuso de inserção direta da SpineGuard/Zavation (parafuso DSG), um parafuso pedicular projetado para ser inserido usando a técnica de inserção direta. Métodos: Parafusos DSG de 5,5 mm e 6,5 mm foram introduzidos em blocos de poliuretano com densidade de 10 PCF (0,16 g/cm3). De acordo com o grupo experimental, os parafusos foram inseridos sem orifício piloto, com orifício e sem macheamento e macheamento diâmetro inferior com mesma geometria. Os testes de resistência dos parafusos foram realizados usando uma máquina de teste universal após a inserção dos parafusos nos blocos de poliuretano. Resultados: Os parafusos inseridos diretamente nos blocos de poliuretano sem orifício piloto e sem macheamento apresentaram uma resistência de arrancamento com significância estatística maior. A inserção do parafuso sem macheamento ou com macheamento com diâmetro inferior apresenta maior resistência ao arrancamento em comparação com o macheamento do mesmo diâmetro. Conclusão: O parafuso DSG apresentou a maior resistência ao arrancamento após sua inserção sem orifício piloto e sem macheamento. Nível de Evidência V, Opinião do Especialista.

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PURPOSE: To evaluate the biomechanical properties of a novel total hip replacement femoral stem. METHODS: Eight pairs of femurs from dog cadavers were used. The femurs were separated into different groups. A novel femoral stem with a convex proximal portion (Stem B) was biomechanically evaluated and compared to awell-known veterinary collared stem (Stem A). Femoral stems were inserted into the contralateral femurs from the same dog, forming 16 constructs. A flexo-compression load was applied on the axial axis of each sample. Maximum strength, deflection, stiffness, and energy absorption were analysed. RESULTS: Group B constructs showed significantly higher values (p ? 0.05) for the variables, except stiffness. The mean maximum strength was 1,347 ± 357 N for Group A and 1,805 ± 123 N for Group B (p ? 0.0069). The mean deflection was5.54 ± 2.63 mm for Group A and 10.03 ± 3.99 mm for Group B (p ? 0.0056). For the energy variable, the force was 6,203 ± 3,488 N/mm for Group A and 12,885 ± 5,056 N/mm for Group B (p ? 0.0054). Stem B had greater maximum strength, deflection, and energy. CONCLUSIONS: The new stem was effective in neutralizing the impact of axial flexion-compression stresses during biomechanical tests in cadaveric models.

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Objective Compare by mechanical tests the pullout resistance and the insertion torque of rough and smooth pedicle screws. Methods Pedicle screws with rough surface and smooth surface, with diameters of 4.8; 5.5 and 6.5 mm, were inserted in polyurethane blocks with density of 10 PCF (0.16 g/cm3). Insertion torque and pullout strength were assessed. Results The pullout strength of the rough surface and smooth surface screws did not differ, except in the group of 4.8 mm diameter screws. In this group, the rough surface screws showed greater resistance to pullout. Conclusion Pedicle screws with a rough surface did not show increased pullout resistance in the acute phase of their insertion in polyurethane blocks compared to smooth surface screws. The rough surface screws had a higher insertion torque than the smooth surface screws, depending on the diameter of the screw and the preparation of the pilot hole.

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Abstract Objective Compare by mechanical tests the pullout resistance and the insertion torque of rough and smooth pedicle screws. Methods Pedicle screws with rough surface and smooth surface, with diameters of 4.8; 5.5 and 6.5 mm, were inserted in polyurethane blocks with density of 10 PCF (0.16 g/cm3). Insertion torque and pullout strength were assessed. Results The pullout strength of the rough surface and smooth surface screws did not differ, except in the group of 4.8 mm diameter screws. In this group, the rough surface screws showed greater resistance to pullout. Conclusion Pedicle screws with a rough surface did not show increased pullout resistance in the acute phase of their insertion in polyurethane blocks compared to smooth surface screws. The rough surface screws had a higher insertion torque than the smooth surface screws, depending on the diameter of the screw and the preparation of the pilot hole.

Resumo Objetivo Comparar por testes mecânicos a resistência ao arrancamento e o torque de inserção do parafuso pedicularjateado e liso. Métodos Parafusos pediculares de superfície áspera e de superfície lisa com diâmetros de 4,8; 5,5 e 6,5 mm foram inseridos em blocos de poliuretano com densidade de 10 PCF (0,16 g/cm3). O torque de inserção e a força de arrancamento foram avaliados. Resultados A força de arrancamento dos parafusos de superfície áspera e de superfície lisa não diferiu, exceto no grupo de parafusos com 4,8 mm de diâmetro. Nesse grupo, os parafusos de superfície áspera apresentaram maior resistência ao arrancamento. Conclusão Os parafusos pediculares de superfície áspera não apresentaram aumento da resistência ao arrancamento na fase aguda de sua inserção em blocos de poliuretano em relação aos parafusos de superfície lisa. Os parafusos de superfície áspera apresentaram maior torque de inserção que os parafusos de superfície lisa, dependendo do diâmetro do parafuso e da preparação do furo piloto.

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ABSTRACT Objectives To observe the influence of the congruence of the tapping of the pilot hole on the anchorage of the pedicle screws. Methods 5.5 and 6.5 mm screws from two vertebral fixation systems (Pedicol and Safe) were inserted into polyurethane blocks. Experimental groups were formed according to the pilot hole preparation: A- drilling with a 2.7 mm drill bit, B- Tapping of the pilot hole with a tap of lesser diameter than the diameter of the screw with a congruent thread design, C- Tapping of the pilot hole with a tap of lesser diameter than the diameter of the screw and an incongruous thread design. The polyurethane blocks with the screws were subjected to a tensile strength test to evaluate the pullout resistance of the screws. Results Using congruent pilot hole tapping of a lesser diameter and congruent thread design increased the pullout resistance of the rough-surface screws (Safe). The screws with a smooth surface (Pedicol) presented greater pullout resistance with tapping of a lesser diameter and incongruous thread design. Conclusions The congruence of the tap used to prepare the pilot hole increased the pullout resistance of the rough-surfaced screws. Level of Evidence III; Therapeutic Study.

RESUMO Objetivos Observar a influência da congruência do macheamento do orifício piloto na ancoragem dos parafusos pediculares. Métodos Parafusos de 5,5 e 6,5 mm, pertencentes a dois sistemas de fixação vertebral (Pedicol e Safe), foram introduzidos em blocos de poliuretano. Os grupos experimentais foram formados de acordo com o preparo do orifício piloto: A - perfuração com broca de 2,7 mm, B - macheamento do orifício piloto com macho de diâmetro inferior ao diâmetro do parafuso e desenho de rosca congruente, C - macheamento do orifício piloto com macho de diâmetro inferior ao diâmetro do parafuso e desenho de rosca incongruente. Os blocos de poliuretano com os parafusos foram submetidos a ensaio de resistência à tração para avaliar a resistência dos parafusos ao arrancamento. Resultados A utilização do macheamento do orifício piloto de menor tamanho e congruente aumentou a resistência ao arrancamento dos parafusos de superfície rugosa (Safe). Os parafusos de superfície lisa (Pedicol) apresentaram maior resistência ao arrancamento com a utilização do macheamento com menor diâmetro e incongruente. Conclusões A congruência do macho utilizado para o preparo do orifício piloto aumentou a resistência ao arrancamento nos parafusos de superfície rugosa. Nível de Evidência III; Estudo terapêutico.

RESUMEN Objetivos Observar la influencia de la congruencia del taladramiento del orificio piloto en el anclaje de los tornillos pediculares. Métodos Fueron introducidos tornillos de 5,5 y 6,5 mm, pertenecientes a dos sistemas de fijación vertebral (Pedicol y Safe) en bloques de poliuretano. Los grupos experimentales fueron formados de acuerdo con la preparación del orificio piloto: A- perforación con broca de 2,7 mm, B- taladramiento del orificio piloto con mecha de diámetro inferior al diámetro del tornillo y diseño de rosca congruente, C- taladramiento del orificio piloto con mecha de diámetro inferior al diámetro del tornillo y diseño de rosca incongruente. Los bloques de poliuretano con los tornillos fueron sometidos a ensayo de resistencia a la tracción para evaluar la resistencia de los tornillos al arrancamiento. Resultados El uso del taladramiento del orificio piloto de menor tamaño y congruente aumentó la resistencia al arrancamiento de los tornillos de superficie rugosa (Safe). Los tornillos de superficie lisa (Pedicol) presentaron mayor resistencia al arrancamiento con el uso del taladramiento con menor diámetro e incongruente. Conclusiones La congruencia de la mecha utilizada para la preparación del orificio piloto aumentó la resistencia al arrancamiento en los tornillos de superficie rugosa. Nivel de Evidencia III; Estudio terapéutico.

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Natural latex extracted from Hevea brasiliensis is one of the materials pointed out as potential tissue regenerators. The use of latex-based membranes in bone regeneration might be an alternative to stimulate bone formation. The aim of this study was to evaluate the effects of latex membranes in guided bone regeneration of defects produced in long bones of rats. Sixty rats were equally divided into latex and control groups, and each group was subdivided into two subgroups according to treatment duration of 1 and 4 weeks. Bone defects with 2.5 mm in diameter were surgically made in the left tibia. In the animals of the latex group, a latex membrane was placed over the bone defect. The samples underwent quantitative histological analysis of bone formation and collagen matrix, immunohistochemical analysis of osteogenic protein markers, assessment of bone mechanical properties and bone densitometry, and radiological assessment. The osteocalcin immunostaining data were submitted to the generalized linear model test with two independent factors. For the other data, the multivariate ANOVA with two independent factors was performed. The use of the latex membrane significantly improved (p < 0.005) the volume of newly formed bone, collagen type I matrix, expression of osteopontin, and bone stiffness, both in the early and late stages of regeneration. In conclusion, the latex membrane was able to promote bone regeneration in long bones.

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The purpose of thisin vitrostudy was to evaluate the influence of a new proposal of implant design and surgical protocol on primary stability in different bone densities. Four groups were tested (n=9): G1 - tapered, cone morse, Ø 4.3 mm x 10 mm in length (Alvim CM); G2 - experimental tapered; G3 - cylindrical, cone morse, Ø 4.0 mm x 11 mm in length (Titamax CM) and G4 - experimental cylindrical. The experimental implants were obtained from a design change in the respective commercial models. The insertion was performed in polyurethane (PU) blocks 0.24 g/cm3(20 pcf) and 0.64 g/cm3(40 pcf), according to different surgical protocols. The primary stability was measured by means of insertion torque (IT) and pullout test. Data were analyzed by ANOVA, Tukey's test (α=0.05) and Pearson's correlation. For IT and pullout, conventional and experimental implants showed no difference between them when inserted in the 20 pcf PU (p>0.05). In the 40 pcf PU, the modified implants exhibited greater IT (p<0.05) and lower pullout (p<0.05) compared to the respective conventional models. The implant design tested associated with the surgical protocol, positively influenced primary stability in higher density bones.

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ABSTRACT Objective: To evaluate the insertion torque and the pulling force of each screw with different diameters and tap. Methods: Polyurethane blocks with a pilot hole of 2.7 mm were used in the study. An experimental group with 5 blocks was formed, the insertion torque was evaluated with a torque meter, and the pullout strength of each Globus screw of 5.5 mm and 6.5 mm was assessed. Results: The comparison of the insertion torque on the 5.5 mm screws with pilot hole without tapping and with a smaller diameter than that of the screw (4.5 mm) and a different thread, and with the tapping with the same diameter as that of the screw (5.5 mm) and equal or different thread presented a statistical difference with a higher value of the insertion torque in the group in which the tapping was not performed. As for the pulling force of the 5.5 mm screw, the non-tapping of the pilot hole resulted in statistical difference with the same diameter of the screw (5.5 mm) and with a different thread of the screw. The pullout force on the 6.5 mm screw was higher in the group where the pilot hole was not tapped according to the non-parametric Kruskal-Wallis test, with significance level of p <0.05 in the comparison of the groups. Conclusions: Pilot hole tapping reduced insertion torque and pullout resistance of the pedicle screw influencing the fixation with tapping with the same screw diameter and different thread design.

RESUMO Objetivo: Avaliar o torque de inserção e a força de arrancamento de cada parafuso com diferentes diâmetros e machos. Métodos: Foram utilizados no estudo blocos de poliuterano com orifício piloto de 2,7mm, sendo feito um grupo experimentais com 5 blocos sendo avaliado o torque de inserção com torquímetro e avaliado o arrancamento de cada parafuso de parafusos Globus 5,5mm e 6,5mm. Resultados: A comparação do torque de inserção nos parafusos de 5,5mm entre a utilização de orifício piloto sem macheamento e o macheamento com diâmetro inferior ao diâmetro do parafuso (4,5mm) e rosca diferente, e com o macheamento com diâmetro igual do parafuso (5,5mm) e com rosca igual ou diferente apresentou diferença estatística com maior valor do torque de inserção no grupo em que o macheamento não foi realizado. Na força de arrancamento do parafuso 5.5mm o não macheamento do orifício piloto apresentou diferença estatística com o mesmo diâmetro do parafuso (5,5mm) e rosca diferente do parafuso. A força de arrancamento no parafuso 6,5mm foi maior no grupo em que o orifício piloto não foi macheado utilizando o teste não paramétrico de Kruskal Wallis com nível de significância adotado (p < 0,05) na comparação dos grupos. Conclusões: O macheamento do orifício piloto diminuiu o torque de inserção e resistência ao arrancamento do parafuso pedicular influenciando a fixação com macheamento com o mesmo diâmetro do parafuso e desenho de rosca diferente.

RESUMEN Objetivo: Evaluar el torque de inserción y la fuerza de extracción de cada tornillo con diferentes diámetros y machos. Métodos: Se utilizaron en el estudio bloques de poliuretano con agujero piloto de 2,7 mm. Se formó un grupo experimental con 5 bloques, y el torque de inserción se evaluó con llave de par y se analizó la fuerza de extracción de cada tornillo Globus de 5,5 mm e 6,5 mm. Resultados: La comparación del torque de inserción en los tornillos de 5,5 mm con agujero piloto sin taladramiento y con un diámetro más pequeño que el del tornillo (4,5 mm) y un roscado diferente, y con el taladramiento con el mismo diámetro que el del tornillo (5,5 mm) y con el roscado igual o diferente presentó una diferencia estadística con un valor más alto del torque de inserción en el grupo en el que no se realizó taladramiento. En cuanto a la fuerza de extracción del tornillo 5,5 mm el no taladramiento del agujero piloto resultó en una diferencia estadística solamente con el mismo diámetro del tornillo (5,5 mm) y con roscado diferente del tornillo. La fuerza de extracción en el tornillo de 6,5 mm fue mayor en el grupo que en el agujero piloto no tuvo taladramiento, de acuerdo con la prueba no paramétrica de Kruskal-Wallis, con nivel de significación de p < 0,05 en la comparación de los grupos. Conclusiones: El taladramiento del agujero piloto redujo el torque de inserción y la resistencia a la extracción del tornillo pedicular, lo que influye con la fijación con taladramiento con el mismo diámetro del tornillo e diferentes diseños de roscado.

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ABSTRACT Background: Distal radius fractures are one of the most common orthopedic injuries and appear in various patterns. Volar plate fixation is not always considered the gold standard treatment. Objective: To measure the resistance of a fragment-specific fixation assembly model obtained by plate fixation associated with different K-wire sizes. Method: In this original experimental study, novel II, axial compression of bone materials was tested. Results: In both groups, the maximum force supported by the fixation method in our study was ten times greater than the physiological load to which the wrist was subjected under physiological conditions. Discussion: In this study, we obtained encouraging results when compared to results reported in the literature. Our study showed that our bone fixating system was mechanically adequate for articular fractures of the intermediate column of the radius (Melone classification). The results were similar or superior to the results of pressure resistance and stiffness when data from the literature was used as reference. Conclusion: The proposed fixation method demonstrated adequate resistance for fixation of the intermediate column of the distal radius. Increasing K wire size caused augmented resistance of the fixation. Level of Evidence II, Prospective comparative study.

RESUMO Introdução: A fratura da extremidade distal do rádio é uma afecção frequente, com variedade de apresentações e nem sempre são passíveis de fixação volar única. Objetivo: Quantificar a resistência obtida no modelo experimental de fixação do fragmento específico, utilizando fio de Kirschner pré moldado, associado a fixação proximal com placa e parafuso. Métodos: Estudo experimental original, nível II, no qual foram realizados ensaios mecânicos com objetivo de avaliar a resistência a compressão axial. Resultados: Os valores de força máxima suportada pelo método de fixação foram pelo menos 10x maiores do que a carga fisiológica a qual o punho é submetido. Discussão: A fixação do tipo fragmento específico vem se mostrando útil e segura, permitindo uma mobilidade precoce segura. Os resultados analisados demonstraram que a montagem proposta em nosso estudo foi mecanicamente adequada para a fixação das fraturas articulares da borda volar ulnar (classificação de Melone) do rádio, tendo resultados semelhantes ou superiores quando comparados a literatura, avaliando a rigidez e a pressão o qual o sistema foi submetido. Conclusão: O método de fixação proposto demonstrou resistência adequada para fixação das fraturas da coluna intermediária do rádio. O aumento da espessura do fio provocou um aumento da força resistida da montagem. Nível de Evidência II, Estudo prospectivo comparativo.

RESUMO

OBJECTIVE: To evaluate the mechanical behavior of the proximal end of the femur submitted to the X-shaped polymethylmethacrylate (PMMA) reinforcement technique. METHODS: Fifteen synthetic femurs, with a Nacional® density of 10 PCF, were divided into two groups: the DX group, with 5 units that were submitted to PMMA reinforcement, and the DP group, with 10 units, which were evaluated intact. The volume of PMMA required, the maximum load, and the absorbed energy to fracture were analyzed by means of a static mechanical bending test simulating a fall on the greater trochanter. RESULTS: A mean of 6 ml of PMMA was used to model the X-reinforcement; it was observed that the DX group presented significantly higher maximum load (median = 1553 N, p = 0.005) and absorbed energy to fracture (median = 9.7 J; p = 0.050) than the DP group (median = 905 N and 6.6 J). CONCLUSION: X-reinforcement of the proximal end of synthetic femurs showed a statistically significant increase in the maximum load and absorbed energy to fracture in the mechanical assay when compared to the control group. Level of Evidence III, Experimental study.

OBJETIVO: Avaliar o comportamento mecânico da extremidade proximal do fêmur submetido à técnica de reforço com polimetilmetacrilato (PMMA) em forma de X. MÉTODOS: Foram utilizados 15 fêmures sintéticos, com densidade de 10 PCF da Nacional®, divididos nos grupos DX, com 5 unidades submetidas ao reforço com PMMA, e DP com 10 unidades, avaliados com sua integridade intacta. Foram analisados o volume de PMMA necessário, os valores da carga máxima e a energia absorvida até a fratura por meio de ensaio mecânico estático de flexão, simulando queda sobre o trocanter maior. RESULTADOS: Foram usados em média 6 ml de PMMA para a modelagem do reforço em X e observou-se que o grupo DX apresentou carga máxima (mediana = 1553 N; p = 0,005) e energia absorvida até fratura (mediana = 9,7 J; p = 0,050) significativamente maior que o grupo DP (mediana = 905 N e 6,6 J). CONCLUSÃO: O reforço em X da extremidade proximal de fêmures sintéticos apresentou incremento estatisticamente significativo da carga máxima e energia absorvida até a fratura no ensaio mecânico em comparação com o grupo controle. Nível de evidência III, Estudo experimental.