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The influence of internal structure on mechanical properties of 3D printed femoral segment from novel optimized biocomposite
Nečas, Aleš ; Schmid, Pavel (referee) ; Přikryl, Radek (advisor)
This diploma thesis presents the development of a new anatomical model of the femur segment based on a biocomposite of poly-3-hydroxybutyrate, polylactic acid, tricalcium phosphate and hydroxyapatite (PHB/PLA/TCP/HA). The model was designed using computed tomography of the patient‘s femur in twelve variants (A1 to A4, B1 to B4, C1 to C4) with different percentages of gyroid filling at the site of the compaction and spongiosis of the real bone. The biocomposite was then 3D printed after the optimized mixture of the new biocomposite (OPT1) was prepared, the printing string‘s chemical and structural characteristics were determined, and the most suitable parameters for 3D printing of the body from this biocomposite were optimized and verified. Furthermore, the pressure load capacity of all twelve variants of 3D printed femur segment models with different percentage densities of their internal gyroid filling was determined. Subsequently, the possibility of predicting the pressure load capacity of the newly developed anatomical femur segment was studied by computer simulation using the numerical model in ANSYS, and the differences in the pressure load capacity values of the PHB/PLA/TCP/HA femur segment in its real mechanical testing were found, compared to the values of the virtual tests using ANSYS. In order to determine the possible tissue resorption rate of this 3D PHB/PLA/TCP/HA biocomposite, the long-term effect (for 4 months) of simulated body fluid on the biodegradation of 3D PHB/PLA/TCP/HA biocomposite bodies with different percentages of gyroid filling (variant I to V) was examined. Subsequently, the biocomposites were subjected to pressure tests while their surface was analyzed by confocal microscopy. The femur segments with 75% filling at the compaction site (variant A) showed the highest average load capacity of 22.20 ± 0.50 kN, while the real femur segment samples had approximately one-quarter lower pressure load capacity compared to the computer simulation. The PHB/PLA/TCP/HA biodegradable bodies with more porous filling (variants II to V) degraded more slowly than the body with 100% filling (variant I), which offers benefits for their clinical use. Their slow degradation also had a beneficial effect on their load-bearing capacity after 4 months.The PHB/PLA/TCP/HA anatomical model of the femoral segment was developed for possible medical use in bone replacement for extensive femoral defects. However, further research is needed before its potential use in medicine.
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