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Comparison of bending modulus and yield strength between outer stratum medium and stratum medium zona alba in equine hooves

Ilka P. Wagner DVM, MAgr1, David M. Hood DVM, PhD2, and Harry A. Hogan PhD3
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  • 1 Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77845.
  • | 2 Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77845.
  • | 3 Department of Mechanical Engineering, College of Engineering, Texas A&M University, College Station, TX 77845.

Abstract

Objective—To determine whether the bending modulus and yield strength of the outer stratum medium (SM) differed from those of the SM zona alba (SMZA) and to what degree they differed. In addition, a comparison was made among our values and values reported elsewhere.

Sample Population—10 normal equine feet.

Procedure—A 3-point bending technique was used to determine the bending modulus and yield strength of the outer SM and SMZA. Efforts were made to minimize biological and technical factors that could influence the bending modulus.

Results—Bending modulus of the outer SM was (mean ± SD) 187.6 ± 41.3 MPa, whereas mean value for the SMZA was 98.2 ± 36.8 MPa. Mean yield strength was 19.4 ± 2.6 MPa for the outer SM and 5.6 ± 1.7 MPa for the SMZA. Values for bending modulus and yield strength differed significantly between the outer SM and SMZA. Significant differences were not detected when the outer SM was loaded in bending from the outer or inner surface.

Conclusions and Clinical Relevance—Potentially, the SMZA could serve as a mechanical buffer zone between the rigid hoof wall and bone and laminar tissues. This buffer zone potentially assists the feet of horses in transmitting a load through the tissues and prevents the most susceptible tissues from becoming damaged. More consistency among tissue selection, preparation, and testing protocols must be attained before an accurate 3-dimensional finite-element model of an equine foot can be constructed. (Am J Vet Res 2001;62:745–751)

Abstract

Objective—To determine whether the bending modulus and yield strength of the outer stratum medium (SM) differed from those of the SM zona alba (SMZA) and to what degree they differed. In addition, a comparison was made among our values and values reported elsewhere.

Sample Population—10 normal equine feet.

Procedure—A 3-point bending technique was used to determine the bending modulus and yield strength of the outer SM and SMZA. Efforts were made to minimize biological and technical factors that could influence the bending modulus.

Results—Bending modulus of the outer SM was (mean ± SD) 187.6 ± 41.3 MPa, whereas mean value for the SMZA was 98.2 ± 36.8 MPa. Mean yield strength was 19.4 ± 2.6 MPa for the outer SM and 5.6 ± 1.7 MPa for the SMZA. Values for bending modulus and yield strength differed significantly between the outer SM and SMZA. Significant differences were not detected when the outer SM was loaded in bending from the outer or inner surface.

Conclusions and Clinical Relevance—Potentially, the SMZA could serve as a mechanical buffer zone between the rigid hoof wall and bone and laminar tissues. This buffer zone potentially assists the feet of horses in transmitting a load through the tissues and prevents the most susceptible tissues from becoming damaged. More consistency among tissue selection, preparation, and testing protocols must be attained before an accurate 3-dimensional finite-element model of an equine foot can be constructed. (Am J Vet Res 2001;62:745–751)