Avaliação de um implante para tratamento de fraturas póstero-laterais do platô tibial

Abstract

Objective: The objective of this study was to validate the fixation and surgical process, in cadavers, of a prototype implant for the treatment of posterolateral fractures of the tibial plateau designed and manufactured by additive manufacturing. Material and Methods: Synthetic bone and anatomical pieces (knees) were used to validate the geometric structure of this new prototype. The implant prototype was designed with a horizontal arm that goes around the entire edge of the lateral tibial plateau. The prototype underwent a qualitative assessment of the congruence and interface between the implant and the lateral proximal region of the tibia. The holes in the plate allow the fixing of 3.5 mm screws to the plate, at a variable angle of 15º around its axis. Plate fixation and congruence in synthetic bone models and cadaver anatomical parts (knees) were evaluated macroscopically and by radiographs in frontal and sagittal views. Fractures were simulated in synthetic bone and fixed with the implant prototype developed. Finally, an access route was made in a cadaver, suitable for the placement of the plate and its fixation to the bone. Results: The implant prototype was obtained by additive manufacturing. Through qualitative analysis, through tests on anatomical pieces (corpses) and radiographs, it was possible to infer that there was excellent adaptation of the plate to the lateral and posterolateral contour of the tibial plateau. The fixation of fractures in synthetic bone showed that the upper arm of the plate allows covering the posterior region of the proximal tibial epiphysis-metaphysis, allowing the fixation of posterolateral fractures. The vertical arm of the plate, which is fixed to the metaphysis-diaphysis of the tibia, prevents translational and rotational movement in the frontal and sagittal planes, which will allow mechanical stability for fracture fixation. Conclusion: The in vitro study showed that the developed implant has dimensions and geometry congruent with the anatomy of the lateral tibial plateau. The variable-angle locking hole system allows the screws to lock onto the plate by varying its angle by 15º around its axis. This allowed placing 4 screws of 3.5 mm in various directions in the axial plane without spatial conflict between the screws. The extended lateral access port, with or without osteotomy of the lateral epicondyle, associated with a mini posterior incision, allows excellent vision of the articular surface, easy implant placement and insertion of posterior screws