, money, and cadaveric tissue). The finite element method has been used to develop computational models of the human carpus. 5,6 A finiteelementmodel of the canine radius has been developed to determine loading conditions that result in replication of
Creation of a finiteelementmodel. (A) L1–2 segment model after mesh generation, consisting of a 0.3–3.0-mm tetrahedral mesh. The area circled by the white frame is the enlarged figure. (B) L1–2 segment model after soft tissue insertion. The L
. All analyses were performed with commercial statistical software, h and values of P < 0.05 were considered significant.
Finiteelementmodeling i was used to evaluate the mechanical behavior (eg, load transfer and bone strain
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
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)
Objective—To examine articular cartilage of the distal
interphalangeal (DIP) joint and distal sesamoidean
impar ligament (DSIL) as well as the deep digital flexor
tendon (DDFT) for adaptive responses to contact
Sample Population—Specimens from 21 horses.
Procedure—Pressure-sensitive film was inserted
between articular surfaces of the DIP joint. The digit
was subjected to a load. Finite element models (FEM)
were developed from the data. The navicular bone,
distal phalanx, and distal attachments of the DSIL and
DDFT were examined histologically.
Results—Analysis of pressure-sensitive film revealed
significant increases in contact area and contact load
at dorsiflexion in the joints between the distal phalanx
and navicular bone and between the middle phalanx
and navicular bone. The FEM results revealed compressive
and shear stresses. Histologic evaluation
revealed loss of proteoglycans in articular cartilage
from older horses (7 to 27 years old). Tidemark
advancement (up to 14 tidemarks) was observed in
articular cartilage between the distal phalanx and navicular
bone in older clinically normal horses. In 2 horses
with navicular syndrome, more tidemarks were
evident. Clinically normal horses had a progressive
increase in proteoglycans in the DSIL and DDFT.
Conclusions and Clinical Relevance—Load on the
navicular bone and associated joints was highest during
dorsiflexion. This increased load may be responsible
for microscopic changes of tidemark advancement
and proteoglycan depletion in the articular cartilage
and of proteoglycan production in the DSIL and
DDFT. Such microscopic changes may represent
adaptive responses to stresses that may progress
and contribute to lameness. (Am J Vet Res 2001;62:414–424)
,18 joint congruency 15 and position of the acetabular cup, 10 is obtained from 3-D CT models in humans with hip dysplasia. The information is incorporated into finiteelementmodels to predict and model disease progression. 21,37,38 The measures
the cranial cavities used simplified mathematical models to derive solutions that expressed the nonlinear relationships between pressure, volume, volume-pressure responses, and compliance. 11–15
Finiteelementmodeling is rapidly gaining popularity
merely indicates that there is contact in a given area above a certain threshold of loading. However, it would be beneficial to know the stress distribution under different loads and how this relates to the density pattern. Finiteelementmodeling coupled