Female Foot Model for High-Heeled Shoe Design - Computational Biomechanics of the Musculoskeletal System - page 33

shod walking, dorsal contact pressure at the forefoot, midfoot, and rear foot had lower values than
pressure at the dorsal toe regions. At the toe region, the first and fifth toes (0.42 and 0.32 MPa) had
considerably large dorsal pressure at push off. Specifically, the dorsal contact pressure at the medial
side of the first toe increased over four times (0.10 to 0.42 MPa) while the dorsal contact pressure at
the superior side remained almost unchanged (0.10 MPa). Meanwhile, the dorsal contact pressure at
the fifth toe increased about three times (0.11 to 0.32 MPa) from heel strike to push off.

2.3.3.2 Joint Contact Pressure, movement, and bone Stress
during donned and Shod walking
The predicted peak joint contact pressure at the MTP joints, tarsometatarsal joint (TMJ), midtar-
sal joint (MTJ), subtalar joint (STJ), and talocrural joint (TCJ) during donned and shod walking
conditions are shown in Figure 2.12. The contact pressure at all MTP joints intensified and reached
their maximum at push off. The maximum contact pressure at MTP joints during push off increased
by at least four times (third MTP) and up to 11 times (first MTP) in comparison to the heel strike
phase, and increased by about three to five times in comparison to the midstance phase. For midfoot
and rearfoot joints, TMJ (22.1 MPa) contact pressure reached its maximum with a similar trend to
the MTP joints for donned and shod conditions. However, the maximum contact pressure of TCJ
(34.6 MPa) and STJ (25.9 MPa) occurred earlier during midstance and decreased at push off. The
peak contact pressure of MTJ from heel strike to push off remained almost the same at around
15 MPa.
Regarding movements of the MTP joints, the first and fifth MTP joints showed the maximum
changes among all MTP joints. The first MTP joint had 3.1 degrees of valgus while the fifth MTP
joint had 1.5 degrees of varus in the transverse plane at donned position compared to the initial posi-
tion (Figure 2.10e). During shod walking, the maximum deformation of MTP joints occurred at push
off, of which the first MTP joint had 4.9 degrees of valgus and the fifth MTP joint had 1.7 degrees of
varus in the transverse plane. In the sagittal plane, the first MTP joint had an increased dorsiflexion
of 3.7 and 7.1 degrees at midstance and push off compared to the heel strike phase, while the fifth
MTP joint increased by 3.2 and 6.1 degrees accordingly. The predicted joint movement character-
istics of the remaining three MTP joints were similar to the first and fifth MTP joints during shod
walking but with less movement, especially in the transverse plane. Meanwhile, the strain in the

36

32

28

24

Donned

20

Heel strike

16

Midstance

12

Push off

8

4

0

FIgure 2.12 Finite element-predicted peak joint contact pressure during donned and shod walking condi-
tions (MTP: metatarsophalangeal joint; TMJ: tarsometatarsal joint; MTJ: midtarsal joint; STJ: subtalar joint;
TCJ: talocrural joint).