Finite element model of the proximal femur under consideration of the hip centralizing forces of the iliotibial tract

2011 ◽  
Vol 26 (1) ◽  
pp. 58-64 ◽  
Author(s):  
K. Birnbaum ◽  
T. Pandorf
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Proximal Femur ◽  
Element Model ◽  
Iliotibial Tract

scholarly journals Experimental Validation of a Voxel-Based Finite Element Model Simulating Femoroplasty of Lytic Lesions in the Proximal Femur

2021 ◽  
Author(s):  
Amelie Sas ◽  
An Sermon ◽  
G. Harry van Lenthe
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bone Cement ◽  
Proximal Femur ◽  
Correlation Coefficients ◽  
Element Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Finite Element Models ◽  
Before And After

Abstract Femoroplasty is a procedure where bone cement is injected percutaneously into a weakened proximal femur. Uncertainty exists whether femoroplasty provides sufficient mechanical strengthening to prevent fractures in patients with femoral bone metastases. Finite element models are promising tools to evaluate the mechanical effectiveness of femoroplasty, but a thorough validation is required. This study validated a voxel-based finite element model against experimental data from eight pairs of human cadaver femurs with artificial metastatic lesions. One femur from each pair was left untreated, while the contralateral femur was augmented with bone cement. Finite element models accurately predicted the femoral strength in the defect (R² = 0.96) and augmented (R² = 0.93) femurs. The modelled surface strain distributions showed a good qualitative match with results from digital image correlation; yet, quantitatively, only moderate correlation coefficients were found for the defect (mean R² = 0.78) and augmented (mean R² = 0.76) femurs. This was attributed to the presence of vessel holes in the femurs and the jagged surface representation of our voxel-based models. Despite some inaccuracies in the surface measurements, the FE models accurately predicted the global bone strength and qualitative deformation behavior, both before and after femoroplasty. Hence, they can offer a useful biomechanical tool to assist clinicians in assessing the need for prophylactic augmentation in patients with metastatic bone disease, as well as in identifying suitable patients for femoroplasty.

A Biomechanical and Finite Element Analysis of Femoral Neck Notching During Hip Resurfacing

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Edward T. Davis ◽  
Michael Olsen ◽  
Rad Zdero ◽  
Marcello Papini ◽  
James P. Waddell ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Femoral Neck ◽  
Finite Element Model ◽  
Proximal Femur ◽  
Equivalent Stress ◽  
Element Model ◽  
Hip Resurfacing ◽  
Stress And Strain ◽  
Element Analysis

Hip resurfacing is an alternative to total hip arthroplasty in which the femoral head surface is replaced with a metallic shell, thus preserving most of the proximal femoral bone stock. Accidental notching of the femoral neck during the procedure may predispose it to fracture. We examined the effect of neck notching on the strength of the proximal femur. Six composite femurs were prepared without a superior femoral neck notch, six were prepared in an inferiorly translated position to create a 2 mm notch, and six were prepared with a 5 mm notch. Six intact synthetic femurs were also tested. The samples were loaded to failure axially. A finite element model of a composite femur with increasing superior notch depths computed maximum equivalent stress and strain distributions. Experimental results showed that resurfaced synthetic femurs were significantly weaker than intact femurs (mean failure of 7034 N, p<0.001). The 2 mm notched group (mean failure of 4034 N) was significantly weaker than the un-notched group (mean failure of 5302 N, p=0.018). The 5 mm notched group (mean failure of 2808 N) was also significantly weaker than both the un-notched and the 2 mm notched groups (p<0.001, p=0.023, respectively). The finite element model showed the maximum equivalent strain in the superior reamed cancellous bone increasing with corresponding notch size. Fracture patterns inferred from equivalent stress distributions were consistent with those obtained from mechanical testing. A superior notch of 2 mm weakened the proximal femur by 24%, and a 5 mm notch weakened it by 47%. The finite element analysis substantiates this showing increasing stress and strain distributions within the prepared femoral neck with increasing notch depth.

Combined finite element model of human proximal femur behaviour considering remodeling and fracture

IRBM ◽  
2013 ◽  
Vol 34 (2) ◽  
pp. 191-195 ◽  
Author(s):  
R. Hambli ◽  
C.-L. Benhamou ◽  
R. Jennane ◽  
E. Lespessailles ◽  
W. Skalli ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Proximal Femur ◽  
Element Model

The Biomechanical Consequence of Insufficient Femoral Component Lateralization and Exposed Cancellous Bone in Hip Resurfacing Arthroplasty

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Michael Olsen ◽  
Edward T. Davis ◽  
Cari M. Whyne ◽  
Rad Zdero ◽  
Emil H. Schemitsch
Keyword(s):  
Finite Element ◽  
Femoral Neck ◽  
Finite Element Model ◽  
Femoral Neck Fracture ◽  
Femoral Component ◽  
Cancellous Bone ◽  
Proximal Femur ◽  
Element Model ◽  
Cement Mantle ◽  
Neck Fracture

Insufficient lateralization of the femoral component coupled with exposed reamed cancellous bone has been speculated to predispose to femoral neck fracture. The current study examined the effect of mediolateral implant position and exposed cancellous bone on the strength of the resurfaced proximal femur. Composite femurs were prepared in three configurations: (1) partial, with the implant placed at the native femoral head offset of the femur, partially exposing reamed cancellous bone; (2) proud, with a medialized implant exposing a circumferential ring of cancellous bone; and (3) complete, with a lateralized implant covering all reamed cancellous bone. Specimens were loaded to failure in axial compression. A finite element model was used to further explore the effect of exposed cancellous bone, cement mantle thickness, and relative valgus orientation on the strain distributions in the resurfaced femur. The proud group (2063 N) was significantly weaker than both the partial (2974 N, p=0.004) and complete groups (5899 N, p=0.001) when tested to failure. The partial group was also significantly weaker than the complete group when tested to failure (p=0.001). The finite element model demonstrated increasing levels of strain in the superior reamed cortical-cancellous bone interface with increasing degree of exposed cancellous bone. The condition of the femoral component medialized as the result of a thick cement mantle had the greatest detrimental impact on strain level in the superior reamed cancellous bone while a valgus oriented implant provided a protective effect. This study provides biomechanical evidence that exposed reamed cancellous bone significantly reduces the load-to-failure and increases maximum strains in the resurfaced proximal femur. The perceived benefit of reconstructing the femur to its native geometry may inherently weaken the proximal femur and increase femoral neck fracture risk if the femoral component is not sufficiently lateralized to cover all unsupported reamed cancellous bone. Relative valgus orientation of the implant may help to minimize the risk of neck fracture if reamed cancellous bone remains exposed following implant impaction.

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