Study of stress variations in single-stance and sideways fall using image-based finite element analysis

Area of Science:

• Biomechanics
• Medical Imaging
• Computational Mechanics

Background:

• Hip fractures are a major health concern, particularly in the elderly.
• The femoral neck is a common site for hip fractures, often resulting from falls.
• Patient-specific computational models are valuable for understanding fracture mechanisms.

Purpose of the Study:

• To investigate and compare stress variations in the femoral neck during single-stance and sideways fall configurations.
• To assess hip fracture risk using a fracture risk indicator under different loading conditions.
• To determine the increased danger of sideways falls for elderly individuals.

Main Methods:

• Generated patient-specific finite element models of ten human femora from Quantitative Computed Tomography (QCT) scan datasets.
• Simulated loading conditions for both single-stance (gait) and sideways fall scenarios with equal load magnitude.
• Calculated stress distributions and fracture risk indicators (stress to yield stress ratio) at the femoral neck.

Main Results:

• Sideways falls induce significantly higher tensile and compressive stresses in the femoral neck compared to single-stance.
• Average variations in fracture risk indicators were at least 24.3% at the superior surface and 8% at the inferior surface between fall and stance.
• These stress differences indicate a substantially elevated fracture risk during sideways falls.

Conclusions:

• Sideways falls pose a greater risk of hip fracture than normal gait due to increased stress concentrations in the femoral neck.
• Image-based finite element analysis (FEA) is an effective tool for predicting patient-specific hip fracture risk.
• Understanding these biomechanical differences can inform strategies for fall prevention and hip fracture mitigation in the elderly.