First Ray Model Comparing Normal and Hallux Valgus Feet - Computational Biomechanics of the Musculoskeletal System - page 49

4 First Ray Model Comparing

Normal and Hallux Valgus Feet

Duo Wai-Chi Wong, Ming Zhang, and
Aaron Kam-Lun Leung

ContentS
Summary .......................................................................................................................................... 49
4.1 Introduction ............................................................................................................................. 50
4.1.1 Background ................................................................................................................. 50
4.1.2 Biomechanical Research on Hallux Valgus and Its Intervention ................................ 50
4.2 Model Development ................................................................................................................ 51
4.2.1 Geometry Construction ............................................................................................... 51
4.2.2 Material Properties ...................................................................................................... 52
4.2.3 Load and Boundary Conditions .................................................................................. 53
4.3 Implications of the Finite Element Model .............................................................................. 53
4.3.1 Bone Alignment and Displacement ............................................................................ 53
4.3.2 Influence on First Ray Joints ...................................................................................... 53
4.3.3 Plantar Pressure Distribution ...................................................................................... 55
4.3.4 Validation of the Model .............................................................................................. 56
4.3.5 Deformity with Load Bearing ..................................................................................... 56
4.3.6 Load Transfer across the First Ray ............................................................................. 56
Acknowledgment ............................................................................................................................. 57
References ........................................................................................................................................ 57

Summary
Hallux valgus has been reported as one of the most common foot problems. Besides its negative
impact on quality of life, it also increases the risk of falling in elderly patients and imposes addi-
tional health risks on patients with diabetic or neuropathic feet. Pathoanatomy, pathomechanics,
and hypermobility studies have been conducted to evaluate the features of hallux valgus. However,
hallux valgus is not yet well understood, and this is reflected by the ineffectiveness of current treat-
ments, complications, and recurrence rates. The current study constructed first ray finite element
(FE) models of a normal foot and a hallux valgus foot to examine the sole effect of extrinsic loading
on the bony structure. The model showed that loading at initial push-off could lead to metatarsus
primus varus and hallux abductor valgus. The hallux valgus foot also showed impaired loading
transfer from the distal phalanx, which could hinder the windlass mechanism. This result showed
that extrinsic loading could predispose the patient to the risk of developing hallux valgus and the
intrinsic stabilization structure, such as ligaments and muscles, could be important in preventing
the development of hallux valgus.

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