Foot and Ankle Model for Surgical Treatment - Computational Biomechanics of the Musculoskeletal System - page 46

3.5 ConCluSIonS
This study reported on the possible outcomes and complications associated with surgical interven-
tion on the first and second TMT joints. A number of biomechanical parameters, including plantar
contact pressure, von Mises stress in the five metatarsal bones, and the contact pressure of joints,
were analyzed during walking instants to identify the biomechanical consequences of joint fusion.
The analysis suggested that fixation of the first two metatarsals and the first two cuneiforms would
influence the stress and pressure distribution of other segments of the foot. The plantar contact
pressure increased in all three instants due to fusion, with the maximum variation occurring during
push off. The fusion model is stiffer than the normal foot. Fusion of the first TMT joint could be a
way to correct flatfoot.
In the analysis of the contact pressure in joints of the hind- and midfoot, the navicular and
cuboid contact pair showed the most considerable variation in midstance. The ankle joint, talona-
vicular, navico-icuneiform, and the fifth meta-cuboid joints also sustained increased contact pres-
sure. Depending on the results, it is possible that the navico-cuboid and the ankle joints have the
greatest potential to succumb to arthritis. Among the five metatarsal bones, the von Mises stress in
the second metatarsal varied the most in midstance. Since the second and third metatarsal bones are
reported to be the segments most susceptible to stress fracture, the increased von Mises stress in the
second metatarsal resulting from the fusion of the two joints could be an indication of an increased
risk of stress fracture.
Optimal surgeries are expected to decrease the complications and negative long-term outcomes,
permitting effective surgical intervention to address foot problems associated with pain, decreased
ambulation, and decreased quality of life. Sufficient understanding of biomechanics could provide
surgeons with more low-risk, sophisticated treatment options that are currently not well known or
considered too risky to undertake. FE analysis could be an effective method to explore the ratio-
nale of biomechanical changes undergone after surgery and provide direct guidelines for surgery
planning.
aCknowledgmentS
This work was supported by the Research Grant Council of Hong Kong (GRF Project no.
PolyU5326/11E), a nd NSFC (11272273, 111201010 01).
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