Chapter 26 The Biomechanics of the Equine Limb and Its Effect on Lameness
Box 26-1 provides short definitions of biomechanical terms used in this chapter.
BOX 26-1 Definition of Common Terms in Biomechanics
Functional Anatomy of the Horse Limb
The Foot as Interface to the Ground
Ability of Structures to Cope with Mechanical Demands
Structural and Material Properties
The ability of structures to deform when loaded and return to their original length when the load is removed allows them to store energy. The amount of energy per unit volume is the area under the linear portion of the stress-strain curve. The capacity of a material to absorb and release energy is often referred to as elastic resilience. The energy a material can absorb before failure defines whether it is “brittle” or “tough”: tough materials are able to absorb considerable elastic energy before failing, whereas brittle materials absorb very little. The digital flexor tendons of a horse are able to store and return a considerable amount of energy during locomotion. Load-deformation curves of tendons are different between loading and unloading, forming a “hysteresis” loop. The area of the loop presents the loss of energy, largely in the form of heat, that occurs during stretch and release (see Figure 68-2). It has been shown that the heat produced by repetition of this mechanism leads to an increase in core temperature, which may contribute to the pathogenesis of tendon injury through thermal damage.4 A detailed description of the pathobiology of tendon injuries is given in Chapter 68.