Biomedical Engineering Reference
In-Depth Information
Figure 12.5 shows the contact pressure distribution patterns in the femoral cartilage and menisci
with 0, 5-, and 10-degree laterally wedged orthoses during mid-stance. The peak contact pressure
at the femur cartilage and menisci among the three wedge conditions were all predicted to occur
in the medial side. In comparison to the 0-degree wedge, the peak contact pressure at the medial
femoral cartilage region decreased by approximately 8.9% using a 5-degree orthosis, and 22.6%
using a 10-degree orthosis. Meanwhile, the peak contact pressure at the medial meniscus decreased
by approximately 10.4% using a 5-degree orthosis and 23.5% using a 10-degree orthosis when com-
pared to the 0-degree model.
Figure 12.6 reveals the lateral-medial shear stress distribution patterns on the tibial plateau
with 0-, 5-, and 10-degree laterally wedged orthoses during mid-stance. The peak shear stresses in
the medial direction among the three wedge conditions were all predicted to occur on the medial
plateau, while the peak shear stresses in the lateral direction all occurred on the lateral plateau. The
lateral-medial shear stress in the tibial plateau appeared at the peripheral meniscal contact region,
which indicated the tendency for the menisci to extrude (Figure 12.6). The peak shear stress in the
medial side of the tibia plateau was much larger than the lateral side due to more prominent extru-
sion for the medial meniscus. In comparison to the 0-degree wedge, the peak shear stress in the
medial direction at the tibial plateau decreased by approximately 13.1% using a 5-degree orthosis,
and 13.9% using a 10-degree orthosis. Shear stress has been shown to be detrimental to cartilage
health because it decreases the expression of cartilage matrix proteins (Lee et al., 2002). The finding
MPa
MPa
7.413
6.795
6.177
5.559
4.942
4.324
3.706
3.089
2.471
1.853
1.235
0.618
0.000
9.575
7.413
6.795
6.177
5.559
4.942
4.324
3.706
3.089
2.471
1.853
1.235
0.618
0.000
12.284
Peak
9.575 MPa
Peak
12.284 MPa
(a)
(b)
MPa
MPa
8.724
11.003
7.413
6.795
6.177
5.559
4.942
4.324
3.706
3.089
2.471
1.853
1.235
0.618
0.000
7.413
6.795
6.177
5.559
4.942
4.324
3.706
3.089
2.471
1.853
1.235
0.618
0.000
Peak
8.724 MPa
Peak
11.003 MPa
(c)
(d)
MPa
MPa
7.413
6.795
6.177
5.559
4.942
4.324
3.706
3.089
2.471
1.853
1.235
0.618
0.000
9.403
7.413
6.795
6.177
5.559
4.942
4.324
3.706
3.089
2.471
1.853
1.235
0.618
0.000
Peak
7.413 MPa
Peak
9.403 MPa
(e)
(f )
FIgure 12.5
(See color insert.)
Contact pressure on the articulation surface of the femur cartilage with
(a) 0-, (c) 5-. and (e) 10-degree laterally wedged orthosis and contact pressure on articulation surfaces of the
meniscus with (b) 0-, (d) 5-, and (f) 10-degree laterally wedged orthosis.
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