Análise biomecânica e cinesiológica humana utilizando redes de bragg em fibra ótica

Abstract

One of the categories of surgical treatment for complex, infected and/or unconsolidated bone fractures is external fixation. Successful treatment with external fixators requires the right time for removal and therefore a reliable consolidation assessment. Early fixator removal can lead to bone refracture, while delayed removal results in unnecessarily prolonged and expensive treatments. Currently, fixator removal follows radiographic evaluation, as the main information resource. This method has disadvantages, patients may be exposed to radiation many times during their treatment and depends on subjective evaluation. Radiographs provide non-specific information about the mechanical quality of the bone callus, só quantitative data are needed to optimize treatment. This work aims to create a new non-invasive tool for the analysis of bone consolidation using optical sensors, optical fiber Bragg gratings – FBG. This work consists of simulation, instrumentation and characterization of the mechanical behavior of Schanz pins of a circular external fixator instrumented to a fêmur. The study of the external fixator was done through finite element analysis, experimental analysis in the laboratory and in vivo analysis. Each analysis was performed in two stages: static and dynamic studies. The results of the static study with the synthetic fêmur showed that at the beginning of the bone union phase, the forces were concentrated on the pins close to the fracture and as the consolidation occurs, the forces gradually began to be concentrated on the more distal pins, according to the results of numerical analysis. The evolution of tension/compression on the pins from the fractured fêmur to the intact fêmur was greater than 90% in all pins. It was possible to differentiate the bone callus stiffness through the deformation detected in the Schanz pins. The results of the dynamic analysis indicated that among all the resonant frequencies, the first seems to be more related to the bone healing process, showing a variation of approximately 22% between the fracture situation and the union, as measured by FBG sensors. In the preliminary in vivo tests, the FBG sensor results demonstrated its technical feasibility to detect the bone callus healing stage. As a non-invasive technology, it has the potential to become an important tool to assist medical staff in analyzing bone consolidation.