Biomedical Engineering Reference
In-Depth Information
Keywords Computed tomography
Finite element analysis
Human femur
Introduction
The femur is the thigh bone and the most important component of the lower limb,
extending from the hip to the knee. It is the heaviest, longest, and strongest bone of
the human body. Being an important structure, it serves two distinct functions:
(1) acts as a supporting structure allowing the weight of the upper body to be
transferred from the hip joint to the knee joint and (2) also acts as a stiff structure
about which muscles act to facilitate movement at both the hip and knee joints.
Koch was the first to give a complete and thorough description of the structure of
the femur, and demonstrated the relations which exist between the structure and
the function as well as between the external and internal architecture of the femur
[
1
]. Macroscopically, the structure of the femur is of two types: (1) cortical or
compact bone which is a dense outer layer mainly resisting bending and (2)
cancellous or spongy or trabecular bone present in the interior of mature bones
mainly resisting compression and bone elements placing or displacing themselves
in the direction of functional pressure according to Wolff's Law [
2
]. The shape of
the femur is asymmetric and curved in all three planes. Hence, a three-dimensional
model is required for a quantitative stress analysis [
3
,
4
]. With minor modifica-
tions, computed tomography (CT) scans of finite element (FE) models can be used
to generate reliable subject-specific FE models that accurately predict strains in
quasi-axial loading configurations [
5
-
8
]. A thorough understanding and behavior
of the femur is essential to elucidate the femur fracture and provide better guidance
to artificial femur replacement. Various works have been carried out to investigate
the loading mode and stress distribution [
9
,
10
]. For better understanding of
femoral loading forces exerted by both the soft and hard tissues of the thigh, a 3D
model is created taking into account all thigh muscles, body weight, contact forces
at the hip, and patello-femoral and knee joints [
11
-
14
]. A mathematical model is
developed to simulate 3D femur bone and femur bone with implant in the femoral
canal, taking into account stress distribution and total displacement during hori-
zontal walking [
15
]. Material properties of femur bones are evaluated to facilitate
further study of total hip joint and replacement of joints in Indian subjects, as these
properties are needed before finite element analysis (FEA) of indigenized hip joint
to study its stability in the bone [
16
,
17
]. The role of ante version in transferring
the load from implant to bone and its influence on total hip arthroplasty (THA) is
determined. In addition, loading of the proximal femur during daily activity, i.e.,
walking and stair climbing is determined. Experimental and analytical approaches
are used to determine the in vivo loading of the hip joint. A numerical muscular
skeleton model is validated against measured in vivo hip contact force [
12
,
18
].
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