Unit:
Κατεύθυνση Εφαρμοσμένη Εμβιομηχανική στην ΟρθοπαιδικήLibrary of the School of Health Sciences
Author:
Bekyras Dionysios
Supervisors info:
Σαββίδου Όλγα, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Παπαγγελόπουλος Παναγιώτης, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Κουλουβάρης Παναγιώτης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Τοπολογική βελτιστοποίηση για ορθοπαιδικά εμφυτεύματα
Translated title:
Topology optimization for orthopaedic implants
Summary:
Failure of orthopedic implants is a common problem that causes pain to patients,
increased hospitalization time and recurrent surgeries. Fracture healing is a complex
process that depends on both biological and biomechanical factors.
The present thesis describes the topological optimization of a solid tibial osteosynthesis
plate. The analyses performed simulated a transverse fracture and its osteosynthesis by
using a plate consisting of a functionally graded lattice structure under axial and
torsional loading.
The topology optimized osteosynthesis plate showed reduced weight and bone contact
area and a porosity of 54.01% with interconnected pores of 300-600 μm in diameter,
within the limits of human bone (300-700 μm). At the same time, the average equivalent
stress increased in the healthy (2.7%) and even more in the callus part of the bone
(8.3%), while the maximum stress in the bone decreased by 4.9%.
The above results showed that the new topology possesses properties capable of
creating a more suitable environment for the faster and more efficient osseointegration
and viability of the bone compared to the corresponding solid. Furthermore, increase in
mean equivalent stress in the bone can mitigate the negative effects of the "stress
shielding" phenomenon, while reduction in the maximum stress is likely to help prevent
any possible damage that can be caused by excessive pressure.
Finally, as far as the new osteosynthesis plate is concerned, the maximum equivalent
stress remained well below the solid titanium alloy yield strength even under three times
the axial compressive force. However, the actual strength of such graded lattice
structures needs further experimental research.
Main subject category:
Health Sciences
Keywords:
Topology optimization, Functionally graded lattice structures, Gyroid, Finite element analysis, Implants
