Left–right differences in the proximal femur’s strength of post-menopausal women: a multicentric finite element study

Abstract

Summary The strength of both femurs was estimated in 198 post-menopausal women through subject-specific finite element models. Important random differences between contralateral femurs were found in a significant number of subjects, pointing to the usefulness of further studies to understand if strength-based classification of patients at risk of fracture can be affected by laterality issues. Introduction Significant, although small, differences exist in mineral density and anatomy of contralateral proximal femurs. These differences, and their combined effect, may result in a side difference in femurs’ strength. However this has never been tested on a large sample of a homogenous population. Methods The strength of both femurs was estimated in 198 post-menopausal women through CT-derived finite element models, built using a validated procedure, in sideways fall conditions. The impact of the resulting asymmetry on the classification of subjects at risk of fracture was analysed. Results The small difference observed between sides (right femur on average 4% stronger than left) was statistically significant but mechanically negligible. In contrast, higher random differences (absolute difference between sides with respect to mean value) were found: on average close to 15% (compared to 9.2% for aBMD alone), with high scatter among the subjects. When using a threshold-based classification, right and left femurs were discordant up to over 20% of cases (K always lower than 0.60), but the left femur was concordant (mean K = 0.84) with the minimum strength between right and left. Conclusion Considering both femurs may be important when trying to classify subjects at risk of failure with strength estimates. Future studies including fracture assessment would be necessary to quantify the real impact.

Are CT-Based Finite Element Model Predictions of Femoral Bone Strengthening Clinically Useful?

“…The most important is that a predictor cannot be calculated for the fractured hip; normally the predictor value for the controlateral intact hip is used instead. Of course, this is an additional potential source of bias; while on average such differences as mechanically negligible, in some random cases differences can be significant [ 28 ].…”

Virtual mechanical tests out‐perform morphometric measures for assessment of mechanical stability of fracture healing in vivo

“…Additionally, the following scoring criteria we included for callus maturity, which are not typically assessed in clinical mRUST: cortical callus formation (AP projection) (0–4), cis‐cortex callus formation (AP projection) (0–4), trans‐cortex callus formation (AP projection) (0–4), cranial cortical gap (ML projection) (0–4), caudal cortical gap (angled projection) (0–4), and callus opacity scores (AP projection) (0–3). All scoring components were summed, resulting in a comprehensive RUS (cRUS) on an interval range 1–27 with higher scores representing more advanced healing. A scoring breakdown can be seen in the supplementary digital content.…”

“…Finite element analysis (FEA) with models derived from computed tomography (CT) scans is increasing in prevalence as a research and clinical diagnostic tool in orthopedics. [1][2][3][4][5][6][7][8] This technique is able to accurately capture both the complex geometries and localized material acquired by the CT scan to build representative animalspecific or patient-specific models. 9,10 FEA can then be used to simulate different loading scenarios and assess the structural biomechanics of the anatomy of interest.…”

Evaluating femoral augmentation to prevent geriatric hip fracture: A scoping review of experimental methods

“…38 Despite being inherently less biofidelic than cadaveric tissue, using synthetic options avoids potential differences arising from differences in hip geometry, which is a limitation of the commonly-reported strategy of using the contralateral femur as a control specimen. Using this type of control for evalution of strength increases also overlooks the potential for differences in both strength 39 and bone mineral density 40 that may exist between left and right femurs from the same donor. Most authors attempt to reduce related effects by randomly selecting the left or right femur for augmentation, but this still leaves any strength differences existing between the two native bones difficult to quantify.…”