Cafeteria Diet Can Affect Bone Microarchitecture in Sedentary and Trained Male Rats.

INTRODUCTION: Poor eating habits and a sedentary lifestyle can impair health. Regular physical activity improves the quality of life and is essential for bone health. Therefore, the present study aimed to evaluate the effects of the cafeteria diet on bone quality of sedentary and exercised rats. METHODS: Sixty young male Wistar rats were divided into six groups (n=10) according to diet composition and activity level, being: SD+CON, standard diet and control; SD+SED, standard diet and sedentary; SD+EX, standard diet and exercised; CD+CON, cafeteria diet and control; CD+SED, cafeteria diet and sedentary; CD+EX, cafeteria diet and exercised. The exercise protocol consisted of 10 ladder-climbing sessions/day, 5 days/week, and the sedentary rats were maintained in individual cages with limited mobility. Body mass and food intake were evaluated weekly. After 10 weeks, the animals were euthanized, and white adipose tissue was collected. The bone structure was evaluated by densitometry, mechanical tests, histomorphometric, and micro-computed tomography analyses. RESULTS: The cafeteria diet increased adipose tissue (p<0.001), decreased bone mineral density (p=0.004), and impaired biomechanical properties (p<0.05) and histomorphometry parameters (p=0.044). The sedentarism decreased bone mineral density (p<0.001) and biomechanical properties (p<0.05), and the exercise did not improve bone properties. CONCLUSION: In this experimental model, it was concluded that the cafeteria diet and a sedentary lifestyle negatively affect bone, and ladder-climbing exercise could not prevent the effects of the unhealthy diet.

In vitro mechanical analysis of X-shaped femoroplasty with polymethyl methacrylate boundary a fall on the greater trochanter.

To evaluate with mechanical testing (MT) using synthetic femurs, an X-shaped femoroplasty technique with polymethyl methacrylate (PMMA), analyzing the results applied to the prophylaxis of proximal femur (PF) fractures caused by low-energy trauma. MT was performed simulating a fall on the greater trochanter, using fifteen Sawbones™ models. They were divided into three experimental groups (n = 5): control (DP) group, drilled without augmentation (DWA) group, and X-shaped augmentation (DX) group. Maximum load, stiffness, absorbed energy and displacement were analyzed primarily in all groups; and secondarily then, morphology and fracture type were verified in all groups while PMMA volume, temperature and time polymerization were analyzed only in the DX group. The MT results obtained for synthetic models respectively in the DP, DWA, and DX groups were: mean maximum load (5562.0 ±â€¯464.8) N, (4798.0 ±â€¯121.2) N, and (7132.0 ±â€¯206.9) N; mean stiffness values (673 ±â€¯64.34) N/mm, (636 ±â€¯8.7) N/mm, and (738 ±â€¯17.13) N/mm, and mean absorbed energy values (36,203 ±â€¯3819) N.mm, (27,617 ±â€¯3011) N.mm, (44,762 ±â€¯3219) N.mm; mean displacement values (13.6 ±â€¯1.45) N, (11.1 ±â€¯0.5) N, and (13.2 ±â€¯0.69) N. The mean volume, temperature reached during filling in the DX group were 9.8 mL, 42.54ºC with 1' 56" of polymerization. The fracture types were similar between the DP and DWA groups, affecting the trochanteric region, as distinctly to those in the DX group, which were restricted to the femoral neck. The values obtained in MT showed statistical significance when analyzed by one-way ANOVA (5%) for maximum load, stiffness, and absorbed energy between groups. In conclusion, X-shaped PMMA augmentation presents a protective biomechanical characteristic against PF fractures generated in synthetic models by boundary a fall on the greater trochanter.

Bone strength is reduced in a neonatal androgenized rat model.

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.

Systemic effects of oral tolerance in bone healing.

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.

Collagen membrane from bovine pericardium for treatment of long bone defect.

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.

The Influence of Thread Tap Mismatch on Pedicle Screw Pullout Strength.

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.

The Influence of Thread Tap Mismatch on Pedicle Screw Pullout Strength / A influência da incompatibilidade do macho de rosca na resistência à extração do parafuso pedicular

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.

Mechanical Analysis after Proximal Femoral Reinforcement with Polymethylmethacrylate in Alternated Double Holes.

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.

DIRECT PEDICLE SCREW INSERTION PULLOUT STRENGTH.

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.

Direct pedicle screw insertion pullout strength / Resistência ao arrancamento do parafuso pedicular de inserção direta

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.

Proposal for a New Fixation Method for Pauwels Type III Femoral Neck Fracture-Metaphyseal Stem: A Finite-Element Analysis.

OBJECTIVE: To evaluate the biomechanical behavior of a metaphyseal stem specifically designed for the fixation of Pauwels type-III femoral neck fractures using finite-element analysis. METHODS: Three different constructions were studied: the dynamic hip screw with a superior anti-rotation screw (DHS + ARS), multiple cannulated screws in an inverted triangle configuration (ASNIS), and the Metaphyseal Nailing System (MNS), a new implant developed by the authors. Vertical and total displacement, localized and total maximum and minimum principal, and the Von Mises peak stresses were evaluated. RESULTS: Results are shown for the DHS + ARS, ASNIS, and MNS models, respectively. Vertical displacement (mm) was 1.49, 3.63, and 1.90; total displacement (mm) was: 5.33, 6.02, and 6.30; localized maximum principal (Mpa) was: 2.77, 4.5, and 1.7; Total maximum principal (Mpa) was: 126, 223, and 531; localized minimum principal (Mpa) was: -1.8, -3.15, and -0.39; total minimum (Mpa) was: -121, -449, and -245; and Von Mises peak stress (MPA) was: 315.5, 326.1, and 286.0. CONCLUSION: The present FEM study showed that the MNS device increases general stresses and reduces localized stresses, when compared to the DHS + ARS and ASNIS constructions used to fix Pauwels type-III femoral neck fracture in synthetic models. In this sense, the MNS showed a low fracture focus shift, conducive to the consolidation environment. The significant reduction in the maximum principal stress, allows to affirm that the main deforming force, the shear, in this fracture pattern, was considerably reduced and the low value of Von Mises obtained, consistent with an implant capable of making an effective load sharing.

Distal radius fracture fixation using volar plate: A comparative study evaluating the biomechanical behavior of uni and bicortical distal screws.

Extensor tendon ruptures caused by bicortical screws impingement following distal radius fracture fixation with volar plates are extensively reported in the literature. Thus, a biomechanical study comparing unicortical and bicortical fixations in intra-articular distal radius fracture models is critical in decision-making regarding distal radius fracture management. Forty-two synthetic radius models were fixed using a variable angle volar distal locking plate with seven screws. They were divided into 6 groups (n = 7): G1/G3/G4 unicortical fixation (75% of anteroposterior distal radius lenght); G2/G4/G6 bicortical fixation. Each group underwent a different mechanical test: axial compression (G1/G2), dorsal flexion (G3/G4), and volar flexion (G5/G6). The load application rate was 5 mm/min and 1000 cycles of 50 to 250 N at 1 Hz were performed between both static tests. Comparative results in the first static test, in the second static test, and in failure generally showed a very similar behavior. Models depicted similar behavior in the second static test when cyclic load was performed. Therefore, one can realize that stiffness differed during dorsal flexion only in the first static test. Maximum force to break the model in axial compression was greater in bicortical than in unicortical construct. Since biomechanical properties are similar, we recommend using unicortical distal locking screws in distal radius fracture fixation with volar plates to prevent extensor tendon ruptures.

Biomechanical evaluation of a new femoral stem design for total hip replacement in a canine model.

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.

The Role of Pedicle Screw Surface on Insertion Torque and Pullout Strength.

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.

The Role of Pedicle Screw Surface on Insertion Torque and Pullout Strength / Influência da superfície dos parafusos pediculares no torque de inserção e resistência ao arrancamento

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.

Influence of the congruence of pilot hole tapping on the anchorage of the pedicle screw / Influência da congruência do macheamento do orifício piloto na ancoragem do parafuso pedicular / Influencia de la congruencia del taladramiento del orificio piloto en el anclaje del tornillo pedicular

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.

Effects of fibrin sealant and bone fragments on defect regeneration performed on rat tibiae: An experimental study.

Fibrin sealant (FS) is a biomaterial that exhibits hemostatic and repairing properties. It has been successfully used as scaffolds and adhesives to improve repair and regeneration of tissues. The objective of this study was to evaluate the effect of FS in the regeneration process of bone defects in male rat tibias through macroscopic, microscopic and mechanical analysis. A bone defect of 2.9 mm was performed on the medial face of the proximal third of the tibia of 40 rats and implanted FS and autologous bone graft (AG). The animals were divided into four groups: animals with bone defect without any treatment (CON), animals treated with fibrin sealant (TFS), animals treated with autologous graft (TAG) and animals treated with fibrin sealant and autologous graft (FSAG). The animals were euthanized 42 days after surgery. Macroscopic analysis showed no difference between the groups (p > 0.05) in relation to tibial weight, but a statistically significant difference (p = 0.005) was observed for their length. Micro-computed tomography (micro-CT) revealed tendentious values regarding bone microarchitecture and FS. Bone mineral densitometry (BMD) showed significance between the FSAG (p = 0.009) and TFS (p = 0.007) groups. The bone mineral content (BMC) presented a significant difference between all groups (p = 0.020). Maximum strength showed a significant difference between the FSAG group (p = 0.007) and the others. The results obtained in relation to the relative stiffness also present a significant difference (p = 0.023). Newly formed bone showed significant differences between groups (p = 0.035). We conclude that bone defect regeneration was directly influenced by the use of FS and AG.

Effects of latex membrane on guided regeneration of long bones.

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.

Influence of an Alternative Implant Design and Surgical Protocol on Primary Stability.

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.

Influence of diameter and geometry in the tapping of the pilot hole in pedicle screws / Influência do diâmetro e geometria no macheamento do orifício piloto nos parafusos pediculares / Influencia del diámetro y geometría en el taladramiento del agujero piloto en tornillos pediculares

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.