RESUMO
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.
RESUMO
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.
RESUMO
INTRODUCTION AND OBJECTIVE: Proximal humerus fractures with metaphysodiaphyseal extension represent a challenge for the orthopedic surgeon due to their reduced incidence and the difficulty in the treatment decision. These can be treated with an intramedullary nail or using the MIPO technique, associating different advantages and complications depending on the procedure. The objective of this study was to compare metaphyseal-diaphyseal fractures of the humerus treated with antegrade intramedullary nailing and those operated using the MIPO technique to see if there were significant differences in terms of functional, clinical, and radiological results. MATERIAL AND METHODS: retrospective, analytical and unicentric review of 29 patients with proximal fracture with metaphyseal-diaphyseal extension treated by MIPO technique and 33 patients surgically treated by antegrade intramedullary nailing (IMN) in our hospital from 2014 to 2020. Demographic, functional, radiographic and clinical data were obtained.. RESULTS: No significant differences were observed between both groups in terms of fracture mechanism (p=0.34), fracture type (p=0.13) or Maresca classification (p=0.32). Surgical time was significantly shorter in the IMN group compared to the MIPO technique (p=0.014). No significant difference was observed regarding the need for blood transfusion (p=0.32). The mean consolidation in the MIPO group was 21 weeks compared to 21 weeks in the IMN, with no significant differences between both groups (p= 0.88). No significant differences were observed between CONSTANT test at one year in the MIPO group versus the IMN group (p=0.79), nor in radial nerve palsies (p=0.28). CONCLUSIONS: Proximal fractures with metaphyseal-diaphyseal extension are a challenge for the orthopedic surgeon due to the infrequency, the complexity of these fractures and the fact that there is no established consensus on the ideal treatment for this type of injury. Both the MIPO technique with the Philos plate and the intramedullary nail are valid options for the treatment of these fractures, with no differences observed in terms of fracture consolidation time or in terms of functional results.
