Objective—To determine the relative contributions of
the muscles, tendons, and accessory ligaments to
the passive force-length properties of the superficial
(SDF) and deep digital flexor (DDF) myotendinous
Sample Population—8 cadaveric forelimbs from 6
Procedure—In vitro, limb configurations during slack
position and myotendinous lengths during subsequent
axial loading of forelimbs were recorded before
and after transection of accessory ligaments.
Expressions were derived to describe the forcelength
behavior of each muscle, tendon, and accessory
ligament-tendon unit; linear stiffness was computed
for these components. The elastic modulus
was established for the SDF and DDF tendons.
Results—Linear stiffness was 2.80 ± 0.38 kN/cm for
the SDF muscle, 3.47 ± 0.66 kN/cm for the DDF muscle,
2.73 ± 0.18 kN/cm for the SDF tendon, 3.22 ±
0.20 kN/cm for the DDF tendon, 6.46 ± 0.85 kN/cm
for the SDF accessory ligament, 1.93 ± 0.11 kN/cm for
the SDF accessory ligament-tendon unit, and 2.47 ±
0.11 kN/cm for the DDF accessory ligament-tendon
unit. The elastic modulus for the SDF and DDF tendons
was 920 ± 77 and 843 ± 56 MPa, respectively.
Conclusions and Clinical Relevance—Both the
muscle-tendon and ligament-tendon portions of SDF
and DDF myotendinous complexes had important
roles in supporting the forelimb of horses. Although
muscle tension can be enhanced by elbow joint flexion
and active contraction, the accessory ligaments
transmitted more force to the distal tendons than did
the muscles under the conditions tested. (Am J Vet
Objective—To calculate normative joint angle, intersegmental
forces, moment of force, and mechanical
power at elbow, antebrachiocarpal, and metacarpophalangeal
joints of dogs at a walk.
Animals—6 clinically normal mixed-breed dogs.
Procedure—Kinetic data were collected via a force
platform, and kinematic data were collected from
forelimbs by use of 3-dimensional videography.
Length, location of the center of mass, total mass,
and mass moment of inertia about the center of mass
were determined for each of 4 segments of the forelimb.
Kinematic data and inertial properties were combined
with vertical and craniocaudal ground reaction
forces to calculate sagittal plane forces and moments
across joints of interest throughout stance phase.
Mechanical power was calculated as the product of
net joint moment and the angular velocity. Joint
angles were calculated directly from kinematic data.
Results—All joint intersegmental forces were similar
to ground reaction forces, with a decrease in magnitude
the more proximal the location of each joint.
Flexor moments were observed at metacarpophalangeal
and antebrachiocarpal joints, and extensor
moments were observed at elbow and shoulder
joints, which provided a net extensor support
moment for the forelimb. Typical profiles of work
existed for each joint.
Conclusions and Clinical Relevance—For clinically
normal dogs of a similar size at a walk, inverse
dynamic calculation of intersegmental forces,
moments of force, and mechanical power for forelimb
joints yielded values of consistent patterns and magnitudes.
These values may be used for comparison in
evaluations of gait in other studies and in treatment of
dogs with forelimb musculoskeletal disease. (Am J Vet Res 2003;64:609–617)
Objective—To compare hoof acceleration and ground reaction force (GRF) data among dirt, synthetic, and turf surfaces in Thoroughbred racehorses.
Animals—3 healthy Thoroughbred racehorses.
Procedures—Forelimb hoof accelerations and GRFs were measured with an accelerometer and a dynamometric horseshoe during trot and canter on dirt, synthetic, and turf track surfaces at a racecourse. Maxima, minima, temporal components, and a measure of vibration were extracted from the data. Acceleration and GRF variables were compared statistically among surfaces.
Results—The synthetic surface often had the lowest peak accelerations, mean vibration, and peak GRFs. Peak acceleration during hoof landing was significantly smaller for the synthetic surface (mean ± SE, 28.5g ± 2.9g) than for the turf surface (42.9g ± 3.8g). Hoof vibrations during hoof landing for the synthetic surface were < 70% of those for the dirt and turf surfaces. Peak GRF for the synthetic surface (11.5 ± 0.4 N/kg) was 83% and 71% of those for the dirt (13.8 ± 0.3 N/kg) and turf surfaces (16.1 ± 0.7 N/kg), respectively.
Conclusions and Clinical Relevance—The relatively low hoof accelerations, vibrations, and peak GRFs associated with the synthetic surface evaluated in the present study indicated that synthetic surfaces have potential for injury reduction in Thoroughbred racehorses. However, because of the unique material properties and different nature of individual dirt, synthetic, and turf racetrack surfaces, extending the results of this study to encompass all track surfaces should be done with caution.