The biomechanical effects of different materials on the application of femoral external fixator: Stainless steel versus titanium alloy and healthy versus osteoporosis bone properties.

Abstract

External fixation stabilizes fractured bones externally, ensuring proper bone union through optimal frame stability. Since different materials provide varying mechanical properties, this study investigated an external fixation system under two conditions: (1) fixator materials (stainless steel vs. titanium alloy) and (2) bone properties (healthy vs. osteoporotic). A 3D fractured femoral bone model was reconstructed with a unilateral fixator and analyzed using the Finite Element Method (FEM) under stance phase loading. The findings revealed that both bone and fixator materials influenced fixation stability. A healthy bone combined with a titanium fixator showed lower stress at the pin-bone interface, potentially reducing the risk of pin tract infection. Interfragmentary movement was 104% higher in osteoporotic bone than in healthy bone, while the titanium fixator exhibited only 1.67% more movement compared to stainless steel, indicating comparable performance. Despite its lighter weight and biocompatibility, titanium's advantage in fixation stability was minimal. However, its lower interface stress may improve clinical outcomes. In contrast, external fixation in osteoporotic patients should be planned cautiously due to higher risk of secondary fractures arising from reduced bone strength and increased micromotion at the fracture site. This study demonstrates that fixator material significantly affects stability. It provides orthopaedic surgeons, clinicians, and researchers with insights that may support improved treatment strategies.