Finite Element Analysis of Femoral Strains in Older Adults During Stair Ascent and Descent

Abstract

Purpose

Understanding the femur load environment during daily activity is necessary for the understanding of risk of femoral pain, pain related falls, and femoral fractures, which could help the design of osteogenic exercises or the preventative methods for older adults.

Methods

Using the finite element femur analysis, this study was to estimate the femoral strains at 9 cross-sections along the long axis of femur for stair ascent and descent (n = 17; age: 50–65 years). Motion analysis and inverse dynamics were combined with musculoskeletal modelling and optimization, then were used as input to a 3-D femur model to estimate femoral strains. Strains at the hip contact force peaks were calculated.

Results

The compressive and tensile strains during stair descent were greater than ascent for all or most cross-sections, especially for the proximal cross-sections of the femur: stair ascent produced − 324.0 ± 103.8 to − 483.7 ± 191.0 µε compressive strains and descent produced − 608.8 ± 288.4 to 1016.0 ± 444.1 µε; stair ascent produced 336.2 ± 105.4 to 391.8 ± 136.9 µε tensile strains and descent produced 546.9 ± 252.8 to 741.7 ± 333.6 µε.

Conclusion

Strains represent the material deformation effect on the bone due to the sum of all the bone external loads. Using bone strains could help future studies analyze load conditions in a more comprehensive way for other physical activities, which predicts the risk of stress fractures and tests if alternative methods (gait type change) could reduce stress and strain effectively.

Funding

chinese universities scientific fund(校2020063)