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

Objective-To determine whether the bending modulus and yield strength of th e 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 mod ulus and yield strength of the outer SM and SMZA. Efforts were made to mini mize biological and technical factors that could influence the bending modu lus. Results-Bending modulus of the outer SM was (mean +/- SD) 187.6 +/- 41.3 MP a, whereas mean value for the SMZA was 98.2 +/- 36.8 MPa. Mean yield streng th 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 betwee n 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 m echanical buffer zone between the rigid hoof wall and bone and laminar tiss ues. This buffer zone potentially assists the feet of horses in transmittin g a load through the tissues and prevents the most susceptible tissues from becoming damaged. More consistency among tissue selection, preparation, an d testing protocols must be attained before an accurate 3-dimensional finit e-element model of an equine foot can be constructed.