Analysis of strain and stress in the equine hoof capsule using finite element methods: comparison with principal strains recorded in vivo

Abstract

Summary Finite‐element (FE) methods have great potential in equine biomechanics in evaluating mechanical stresses and strains in tissues deep within the hoof. In this study, we critically assessed that potential by comparing results of FE analyses of capsular strain with in vivo data. Nine FE models were developed, corresponding to the shape of hooves for which in vivo principal strain data are available. Each model had the wall, laminarjunction, sole and distal phalanx (PIII). In a first loading condition (LC1), force is distributed uniformly to the bearing surface of the wall to determine reaction forces and moment on PIII. These reaction forces were subsequently applied to PIII in loading condition 2 (LC2) to simulate loading via the skeleton. Magnitude of the force resultant was equivalent to the vertical force on the hoof at midstance. Principal compressive strains ε2 were calculated at the locations of 5 rosette gauges on the real hooves and are compared with the in vivo strains at midstance. FE strains were from 16 to 221% of comparable in vivo values, averaging 104%. All models in this, and reports by other workers, show predominance of stress and strain at the toe to a greater extent than in the real hoof. The primary conclusion is that FE modelling of strain in the hoof capsule or deeper tissues of individual horses should not be attempted without corroborating experimental data.

Equine Hoof Wall Tubule Density and Morphology

“…The distribution of the loads and the greater MTD on the medial wall (more upright) are consistent with this notion that tubules are supportive structures. However, during hoof loading superficial wall measurements of the forces do not consistently align with tubular orientation [21]. Alternatively, greater tensile and strain forces may be occurring internally, producing a stratification of physical forces within the stratum medium.…”

“…Previous works have observed that the primary epidermal laminae (PEL) densities vary in different horse populations and this variation may relate to stresses along the hoof wall [2,6,10,21]. However, studies examining equine hoof wall tubules and/or tubular density have not yet shown, if or how tubular architecture may vary or respond to environmental forces in ways similar to laminae.…”

The effect of hoof angle variations on dorsal lamellar load in the equine hoof

“…These test simulation results show that the material model is capable of reproducing the measured tissue behaviour. Following Thomason et al . (2002) we used the same material properties for the solar dermis as the laminar junction.…”

“…Other authors (Hinterhofer et al . 2000; Thomason et al . 2002) used a value for the Young's modulus of the sole tissue that corresponded to about one‐third of the mean wall stiffness.…”

Correspondence

“…This aspect of the model has been derived directly from published experimental data (Hinterhofer et al 1998 [5]; Douglas et al 1998 [6]; Kasapi and Gosline 1999 [7]). The load response of hoof tissues, and in particular the laminar junction and hoof wall tissues, is one aspect of this model in which we have a good degree of confidence.…”