Chapters authored
Viscoelasticity in Foot-Ground Interaction
Mechanical properties of the plantar soft tissue, which acts as the interface between the skeleton and the ground, play an important role in distributing the force underneath the foot and in influencing the load transfer to the entire body during weight-bearing activities. Hence, understanding the mechanical behaviour of the plantar soft tissue and the mathematical equations that govern such behaviour can have important applications in investigating the effect of disease and injuries on soft tissue function. The plantar soft tissue of the foot shows a viscoelastic behaviour, where the reaction force is not only dependent on the amount of deformation but also influenced by the deformation rate. This chapter provides an insight into the mechanical behaviour of plantar soft tissue during loading with specific emphasis on heel pad, which is the first point of contact during normal gait. Furthermore, the methods of assessing the mechanical behaviour including the in vitro/in situ and in vivo are discussed, and examples of creep, stress relaxation, rate dependency and hysteresis behaviour of the heel pad are shown. In addition, the viscoelastic models that represent the mechanical behaviour of the plantar soft tissue under load along with the equations that govern this behaviour are elaborated and discussed.
Part of the book: Viscoelastic and Viscoplastic Materials
Cutaneous Microcirculation of the Foot
The skin, the body’s largest organ, acts as a shield against infections and injuries. The skin has an inherent ability to autoregulate its blood flow, which depends on extrinsic/intrinsic factors. This function is facilitated by a complex regulatory system that includes local regulation of cutanemicrocirculation involving sensory and autonomic fibres. These play important roles in thermoregulation, maintenance of homeostasis, defence, inflammatory response and nutrition. Any structural or functional damage to the microvasculature can lead to an incongruity in the demand and supply either due to physiological or pathological reasons. Besides, the small fibre nerves supplied by the microvessels can suffer from hypoxia, which in turn can cause problems. By understanding these functional aspects and applying this knowledge for assessment, the complex pathophysiological mechanisms of diseases like Raynaud’s and diabetic-foot complications can be better understood. Moreover, microcirculation is crucial for wound healing in both diabetic foot and in pressure ulcers. This chapter aims to discuss the anatomy and physiology of foot microcirculation and its involvement in the pathobiology of certain diseases. Furthermore, various microcirculatory assessment tools and methods are discussed. Acquiring this knowledge can be helpful in providing more effective prevention, diagnosis, and treatment of microcirculatory diseases of the foot.
Part of the book: Microcirculation