Biomechanical Evaluation of Unstable Intertrochanteric Fractures Fixation with Different Implants: A Finite Element Analysis Study

Abstract

Purpose Unstable intertrochanteric fractures are one of the most difficult to treat in older hip fractures. In this study, we simulated unstable intertrochanteric fractures AO/OTA 31 A2.3 by finite element analysis to compare the biomechanical stability of the three implants most commonly used in clinical treatment at this stage. Methods We used Mimics, Geomagic studio, UG-NX, Hypermesh and other software to establish the model of unstable intertrochanteric fracture (AO/OTA 31 A2.3) and three internal fixation models of Dynamic hip screw (DHS), Proximal Femoral Nail Antirotation (PFNA), and InterTAN. After assembly, Abaqus software was used to analyze and calculate the Von Mises stress distribution, strain distribution, and displacement distribution of each group of fracture internal fixation models when the force was applied in the gait. Results Our experimental results show that under 2100N load, the peak stress of the InterTAN was 783.4Mpa, while the peak stress of PFNA and DHS was 603.7Mpa and 763.5Mpa. In InterTAN, the peak strain was 0.41% at the load of 2100N; in PFNA, the peak strain was 0.58%; in DHS, the peak strain was 0.69%. And InterTAN structure had a maximum displacement of 5.74 mm at a load of 2100N. PFNA structure performed the maximum displacement of 9.44 mm, and DHS was 21.76 mm. The maximum displacement of the complete fracture model under InterTAN fixation was 6.7 mm, and the maximum displacement values for the PFNA fixation model and DHS fixation model were 10.84 mm and 22.8 mm. Conclusions Our finite element analysis results indicate that when subjected to the same mechanical loads, InterTAN experiences lower yield strain and displacement compared to DHS and PFNA. Only under higher loads does InterTAN exhibit higher peak stress. It demonstrates superior biomechanical performance, making it a better choice for fixing unstable intertrochanteric fractures. Additionally, intramedullary fixation proves to be more effective than extramedullary fixation.