Influence of Exercise History on the Proximal Femur Strength; Finite Element Analysis of Female Athletes
Abe, Shinya (2013)
Abe, Shinya
2013
Master's Degree Programme in Biomedical Engineering
Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering
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Hyväksymispäivämäärä
2013-06-05
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201306121198
https://urn.fi/URN:NBN:fi:tty-201306121198
Tiivistelmä
Bone structure and material properties adapt to mechanical loading, and accordingly exercise highly influences bone’s functional adaptation. Studying bones from various athletic subjects provides us a good opportunity to understand the mechanism of exercise-induced structural change in bone. Constructing 3D bone models has become available with current medical imaging techniques and is essential to investigate this mechanism. Finite element (FE) models of these bone models enable us to solve complicated numerical problems. In bone biomechanics, they provide an appropriate tool for assessing bone strength, detection of hip fracture prone regions and revealing the beneficial type of exercises to strengthen those regions. Hip fracture is a worldwide medical problem and majority of them are directly caused by falling. Cortical wall of the femoral neck get thinner with aging and some regions become more prone to the fracture. Impact loading exercises have positive effect on maintaining and/or increasing cortical thickness, increasing thus bone strength. This adaptation may be a key in preventing hip fractures. Therefore, the objective of this thesis was to investigate if the exercise history is associated with femoral neck bone strength in a lateral fall condition. To achieve this, MRI-based FE models of 36 young competitive female athletes’ proximal femurs were created. These subjects were categorized into 5 different groups based on the exercise history; 1) High-Impact, 2) Odd-Impact, 3) High-Magnitude, 4) Repetitive Low-Impact, 5) Repetitive Non-Impact, and compared to a control group.
The proximal femur was modeled as the linear elastic, isotropic and homogenous material. Regional mean cortical and trabecular vonMises stresses were calculated for 8 anatomical sectors of the smallest cross-section of the femoral neck. Statistical analysis based on the nonparametric Mann-Whitney text was performed to investigate the difference in the sector-wise stress between each athlete’s group and the control group.
At superior cortical region, ~17MPa stress was observed in the Odd-Impact group compared to ~20MPa stress in the control group. This result indicates that the proximal femur in the Odd-Impact groups has somewhat higher load bearing capacity in the lateral fall. Thus, Odd-Impact exercise performed in adulthood could be an optimal means to prevent bone fragility in older age. However, statistical power was very low and the findings from this study are preliminary and indicative only. Future study should include not only more subjects to obtain better statistical confidence, but also be based on more realistic the FE models and different loading conditions, including the dynamic situation.
The proximal femur was modeled as the linear elastic, isotropic and homogenous material. Regional mean cortical and trabecular vonMises stresses were calculated for 8 anatomical sectors of the smallest cross-section of the femoral neck. Statistical analysis based on the nonparametric Mann-Whitney text was performed to investigate the difference in the sector-wise stress between each athlete’s group and the control group.
At superior cortical region, ~17MPa stress was observed in the Odd-Impact group compared to ~20MPa stress in the control group. This result indicates that the proximal femur in the Odd-Impact groups has somewhat higher load bearing capacity in the lateral fall. Thus, Odd-Impact exercise performed in adulthood could be an optimal means to prevent bone fragility in older age. However, statistical power was very low and the findings from this study are preliminary and indicative only. Future study should include not only more subjects to obtain better statistical confidence, but also be based on more realistic the FE models and different loading conditions, including the dynamic situation.