[Translated article] Mechanical resistance of polylactic acid bone matrices developed by 3D printing for the reconstruction of bone defects.

INTRODUCTION: Bone defects are one of the main limitations in orthopaedic surgery and traumatology. For this reason, multiple bone replacement systems have been developed, either by prosthetic implant or by substitution with osteoforming substances, whose limitations are their survival and lack of structurality, respectively. The objective of this work is the generation of a new material for the creation of biologically active structures that have sufficient tensile strength to maintain the structure during remodelling. MATERIAL AND METHODS: A new filament based on the fusion of natural polylactide acid (PLA) powder was designed for the generation of pieces by means of fused deposition modelling (FDM) on which to carry out tensile mechanical tests of osteosynthesis material. A total of 13 groups with different cortical thickness, filling and layer height were carried out, with 10 tensile tests in each group, defining the tensile breaking limit for each group. The regression lines for each group and their mechanical resistance to traction on the filament used were determined. RESULTS: The filament ratio per contact surface unit with the osteosynthesis used was the main determinant of the mechanical resistance to traction, either at the expense of the increase in cortical thickness or by the increase in the percentage of cancellous bone filling. Layer height had a minor effect on tensile strength. The regression value was high for cortical thickness and cancellous filling, being elements with a predictable biomechanical behaviour. CONCLUSIONS: The new methodology allows the creation of personalised neutral and implantable PLA bone matrices for the reconstruction of large bone defects by means of 3D printing by FDM with a mechanical resistance to traction greater than that of current biological support structures.

Mechanical resistance of polylactic acid bone matrices developed by 3D printing for the reconstruction of bone defects. / Resistencia mecánica de matrices óseas de ácido poliláctico desarrolladas por impresión 3D para la reconstrucción de defectos óseos.

INTRODUCTION: Bone defects are one of the main limitations in orthopedic surgery and traumatology. For this reason, multiple bone replacement systems have been developed, either by prosthetic implant or by substitution with osteoforming substances, whose limitations are their survival and lack of structurality, respectively. The objective of this work is the generation of a new material for the creation of biologically active structures that have sufficient tensile strength to maintain the structure during remodeling. MATERIAL AND METHODS: A new filament based on the fusion of natural polylactide acid (PLA) powder was designed for the generation of pieces by means of fused deposition modeling (FDM) on which to carry out tensile mechanical tests of osteosynthesis material. A total of 13 groups with different cortical thickness, filling and layer height were carried out, with 10 tensile tests in each group, defining the tensile breaking limit for each group. The regression lines for each group and their mechanical resistance to traction on the filament used were determined. RESULTS: The filament ratio per contact surface unit with the osteosynthesis used was the main determinant of the mechanical resistance to traction, either at the expense of the increase in cortical thickness or by the increase in the percentage of cancellous bone filling. Layer height had a minor effect on tensile strength. The regression value was high for cortical thickness and cancellous filling, being elements with a predictable biomechanical behavior. CONCLUSIONS: The new methodology allows the creation of personalized neutral and implantable PLA bone matrices for the reconstruction of large bone defects by means of 3D printing by FDM with a mechanical resistance to traction greater than that of current biological support structures.

[Alternatives for the treatment of complex tibial pilon fractures]. / Alternativas para el tratamiento de las fracturas complejas de pilón tibial.

Tibial pilon fractures are one of the most severe types of fractures, not only due to the complexity of their treatment, but also due to the important sequelae they may cause. Moreover, an important percentage of them are open fractures or importantly involve the soft tissues, thus making treatment even more difficult. Thirty-seven patients with tibial pilon fractures treated surgically were included in this study. The results of the FREMAP functional assessment scale were analyzed together with Burwell-Charnley's radiographic criteria. Although there is no consensus on which is the best treatment, it is evident that combined treatment including external and internal fixation with a plate provides the best results.

Alternativas para el tratamiento de las fracturas complejas de pilón tibial / Alternatives for the treatment of complex tibial pilon fractures

Las fracturas de pilón tibial representan una de las fracturas más graves, no sólo por la complejidad de su tratamiento, sino también por las importantes secuelas que pueden originar. Además de que un importante porcentaje de éstas son abiertas o con importante afectación de partes blandas, lo que dificulta aún más su tratamiento. Se revisaron 37 pacientes con fractura de pilón tibial tratados de forma quirúrgica, analizando los resultados con la escala de valoración funcional FREMAP y con los criterios radiográficos de Burwell-Charnley. Aunque no existe consenso en relación al tratamiento ideal, parece evidente que el tratamiento combinado con fijación externa e interna con placa ofrece los mejores resultados.

Tibial pilon fractures are one of the most severe types of fractures, not only due to the complexity of their treatment, but also due to the important sequelae they may cause. Moreover, an important percentage of them are open fractures or importantly involve the soft tissues, thus making treatment even more difficult. Thirty-seven patients with tibial pilon fractures treated surgically were included in this study. The results of the FREMAP functional assessment scale were analyzed together with Burwell-Charnley's radiographic criteria. Although there is no consensus on which is the best treatment, it is evident that combined treatment including external and internal fixation with a plate provides the best results.