CESAR AUGUSTO MARTINS PEREIRA
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Ortopediae Traumatologia, Faculdade de Medicina
LIM/41 - Laboratório de Investigação Médica do Sistema Músculoesquelético, Hospital das Clínicas, Faculdade de Medicina
LIM/41 - Laboratório de Investigação Médica do Sistema Músculoesquelético, Hospital das Clínicas, Faculdade de Medicina
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article Estudo biomecânico do comportamento de diferentes espessuras de capa de cimento ósseo em novo modelo de prótese modular diafisária femoral em cão submetidas a ensaio de torção(2013) NINA, Marcos Ishimoto Della; FERRIGNO, Cassio Ricardo Auada; PEREIRA, Cesar Augusto Martins; ALVES, Flavio Rocha; HERNANDEZ, Arnaldo JoseBackground: The feasibility of modular cemented prosthesis in the femoral diaphysis was demonstrated in dogs, but several authors report loosening of bone-cement-implant interface as a major complication and have yet to reach a consensus on the ideal cement layer thickness for reducing postoperative morbidity. The objective of this study was to evaluate the stabilization of the prosthesis using different thicknesses of cement layer, subjected to torsion forces. Materials, Methods & Results: For this study 48 femurs from 24 dogs weighing over 15 kg were used. The animals used did not have any prior diagnosis of bone or nutritional diseases, which was an exclusion criteria for this study. All biological materials were obtained immediately after death or euthanasia of the animal, and then subjected to conventional storage in a freezer at a temperature of - 24 degrees C. The prosthesis was composed of a cylindrical part with rods for attachment to the intramedullary canal, made of alloy steel 316L. After thawing the femurs and subsequent stabilization at room temperature we performed osteotomies of the femoral diaphysis with an oscillating saw and the installation of the prosthesis. As preparatory measures for prosthesis fixation with cement, the intramedullary canals were cleaned, washed with saline and aspirated. They were separated in four groups, the first group with eight femurs used a cement mantle of 1.0 to 1.5 mm, the second group, with eight femurs, used a cement mantle of 2.0 to 2.5 mm and the third group, with eight femurs, used a cement layer of 3.0 to 3.5 mm. The femurs were submitted to destructive torsion tests using a universal testing machine with a load cell of 981 N (100 kg) and an essay speed of 22 mm / min. They were evaluated due to the values of torsional rigidity and maximum torque shown by the implant, bone and bone cement interface. The fourth group consisted of the remaining intact femurs, they were evaluated using the same torsion test used on the other groups. The results were analyzed using the Statistical Analysis System (SAS, 2001) and the normality of residuals was previously verified by the Shapiro-Wilk test. It was established to conduct the testing using an external rotation protocol in order to standardize, assuming a situation where the dog was in movement during a uniform curvilinear motion, trying to mimic a situation where the rotational forces were acting more significantly on the femur. Discussion: In our study the importance of cleaning up the intramedullary canal for proper bone cement penetration, a good reaming of the intramedullary canal and drying the area before the cement implantation was made clear. Statistical analysis showed that the thicknesses of the cement layer ranging from 1 mm to 2.5 mm, although bringing a gradual increase in maximum torque and torsional rigidity, are not sufficient to be statistically significant and may be considered equal in their biomechanical behavior assessed by this study. A similar result was found when we compared the 2 mm to 3.5 mm layers. The comparison that was statistically significant and can be considered in relation to the different biomechanical behavior of the cement layer was seen between the group I of 1 mm to 1.5 mm, and group III of 3 mm to 3.5 mm. Although some results were not statistically significant we must remember that, in absolute values, the torsional rigidity and maximum torque increased linearly with the increasing of the cement layer. From these results we can infer about the real advantage of using a thicker cement layer over an increment in the diameter of the intramedullary component, giving greater resistance to the prosthesis.- A BIOMECHANICAL COMPARISON OF MATCHED FOUR-STRAND AND FIVE-STRAND SEMITENDINOSUS-GRACILIS GRAFTS(2021) BARROS, Marcos Amstalden; COSTA, Sandokan Cavalcante; JARAMILLO, Diego Eduardo Rubio; ALMEIDA, Adriano Marques de; PEREIRA, Cesar Augusto Martins; FERNANDES, Tiago Lazzaretti; NARDELLI, Julio Cesar Carvalho; ANNICHINO, Marcel Fruschein; PEDRINELLI, Andre; HERNANDEZ, Arnaldo JoseIntroduction: Recent studies have shown that the likelihood of semitendinosus-gracilis graft rupture is inversely correlated to its diameter. A graft can be prepared in a five-strand or four-strand fashion to increase its diameter. However, the biomechanical superiority of five-strand semitendinosus-gracilis grafts is still under debate. Objective: This study aimed to evaluate the biomechanical characteristics of matched four-strand and five-strand human semitendinosus-gracilis grafts. Methods: We evaluated semitendinosus-gracilis tendons harvested from ten fresh human male and female cadavers, aged 18-60 years. Four-strand or five-strand grafts were prepared with the tendons and fixed to wooden tunnels with interference screws. Each graft was submitted to axial traction at 20 mm/min until rupture; the tests were donor matched. Data were recorded in real time and included the analysis of the area, diameter, force, maximum deformation and stiffness of the grafts. Results: The diameter, area and tunnel size were significantly greater in the five-strand grafts than in the four-strand grafts. There were no significant differences in biomechanical properties. The area and diameter of the graft were positively correlated to stiffness, and inversely correlated to elasticity. There was no significant correlation between graft size and maximum force at failure, maximum deformation or maximum tension. Conclusion: Five-strand hamstring grafts have greater area, diameter and tunnel size than fourstrand grafts. There were no significant differences in biomechanical properties. In this model using interference screw fixation, the increases in area and diameter were correlated with an increase in stiffness and a decrease in elasticity.
- The biomechanical effects of graft rotation on ACL reconstruction tunnel mismatch(2017) OLIVEIRA, Danilo Ricardo Okiishi de; GARCIA, Eduardo Takahashi; FUSO, Fernando Augusto Freitas; PEREIRA, Cesar Augusto Martins; LAGES, Marco Martins; ALMEIDA, Adriano Marques de; FERNANDES, Tiago Lazzaretti; PEDRINELLI, Andre; HERNANDEZ, Arnaldo JoseBone block protrusion out of the tibial tunnel due to a relatively long graft is a common complication in anterior cruciate ligament surgical reconstruction with a patellar tendon. One possible solution is to shorten the patellar tendon graft already fixed in the femur by applying external rotation. This study aimed to evaluate the degree of shortening and biomechanical changes in porcine patellar grafts subjected to relatively higher degrees of rotation. Data obtained with rotations of 0A degrees, 540A degrees, 720A degrees, and 900A degrees were compared. Forty patellar porcine ligaments were subjected to biomechanical tests of degree of shortening, modulus of elasticity and maximum tension in the tendon before rupture. Tests were conducted using a universal mechanical testing machine and a computerized system for acquiring strength and deformation data. Progressive shortening of the patellar ligament occurred with rotations of 0A degrees, 540A degrees and 720A degrees. However, the degree of shortening showed no statistically significant difference as rotation increased from 720A degrees to 900A degrees. Decreased modulus of elasticity was observed compared with the graft rotation at 0A degrees in all groups tested, but no statistically significant differences were observed among 540A degrees, 720A degrees and 900A degrees. The maximum tension of the patellar tendon showed no change before rupture, regardless of the degree of rotation. Rotating the patellar tendon is an efficient method for shortening a relatively long graft; however, more biomechanical studies are necessary to recommend this technique in clinical practice owing to the resulting decrease in graft stiffness that could compromise knee stability.
- Posterolateral anatomical reconstruction restored varus but not rotational stability: A biomechanical study with cadavers(2015) SERBINO JUNIOR, Jose Wilson; ALBUQUERQUE, Roberto Freire da Mota; PEREIRA, Cesar Augusto M.; REZENDE, Marcia Uchoa de; LASMAR, Rodrigo Campos Pace; HERNANDEZ, Arnaldo JoseBackground and aim: Lesions to the posterolateral corner (PLC) of the knee are rarely isolated injuries, and they are potentially devastating, leading to progressive chondral injury, with important functional impairment The objectives of this biomechanical study were to evaluate angular deformation with two loads and considering four flexion angles of the knee, varus and external rotation and in three situations of integrity, reconstruction and injury of posterolateral knee structures. Methods: The posterolateral structures of 10 cadaveric knees were submitted to three biomechanical assays: in the ""intact condition"", ""injured"", and ""reconstructed"". The technique used for the reconstruction was the one proposed by LaPrade et al., but with autografts of hamstring tendons instead. A device was designed to apply loads of 2 and 5 N m, with zero, 30 degrees, 60 degrees and 90 degrees of knee flexion, in varus or in external rotation, measuring angular deformation with photogoniometry. Results: The anatomical reconstruction of the PLC proposed here did restore varus stability in all flexion angles (p < 0.005), but not rotational stability. External rotation deformation at 90 degrees was similar in all test conditions. In knee extension, external rotation was stabilized only at 2 Nm. At 60 degrees, external rotation was partially stabilized (p < 0.05). Conclusions: The anatomical PLC reconstruction using hamstring tendons restored varus but not external rotational stability. Clinical Relevance: The reconstruction of posterolateral corner injuries with autologous allografts is very important for regions were tissue banks are not available. This technique may be a first step to achieve this goal.