STRESS STRAIN BEHAVIOR OF THE EQUINE LAMINAR JUNCTION/

The equine laminar junction plays a vital role in transferring the for ces of weight-bearing between the epidermal hoof wall and the bone of the third phalanx, but the way in which it performs this function is p oorly understood, Using samples from sites varying proximodistally and circumferentially around the hoof, the stress/strain behaviour of thi s tissue was characterised in three directions: radial tension and pro ximodistal and mediolateral shear, The influences of toe angle and len gth were also examined. For all three test directions, the modulus of elasticity increased with increasing strain magnitude. The mean modulu s of elasticity in tension was 18.25 +/- 5.38 MPa (mean +/- 1 S.D., N= 116; mean strain 0.25), In proximodistal shear, the mean shear modulus was 5.38 +/- 1.49 MPa (N=76; mean shear strain 0.48) and in mediolate ral shear 2.57 +/- 0.91 MPa (N=66: mean shear strain 0.81), In many ca ses, the individual hoof or horse from which the samples were taken si gnificantly affected the value of the modulus, suggesting that mechani cal history may affect the material properties of this tissue. Few bio logically significant variations with location, toe length or toe angl e were unambiguously demonstrated, suggesting that the material proper ties of the laminar junction are independent of position, despite appa rent regional variations in function, and that foot shape is not a maj or determinant of material properties.