Morphologische Grundlagen für ein Forward-Dynamik-Modell der Schultergliedmaße des Deutschen Schäferhundes und invers dynamische Untersuchungen zu den gelenkresultierenden Kräften der großen Gliedmaßengelenke

The forces in the limb joints in the dog were investigated for the
first time in the German Shepherd. The main focus lay on the joints
of the forelimb, as these have been hardly investigated so far. But
also the joint forces of the joints of the hind limb were
demonstrated. Additionally the foundations for a forward dynamic
model were developed for the forelimb. The study constitutes two
parts. The aim of the first part was to develop the foundations for
a forward dynamic model. For that reason the skeletal muscles of
the forelimb as well as the shoulder girdle musculature of five
German Shepherds were analysed. The length of the fibres, the
weight and the angle of pennation for the muscle fibers were used
to determine the physiological cross-section area. Individual
extensive muscles of the shoulder girdle musculature were divided
into various portions, for a better determination of the lines of
actions for these muscles. The coordinates of the muscles various
points of origin and insertion were measured on the skeleton of a
German Shepherd. The straight line of these skeletal points were
determined as action lines, in order to calculate the moment arm of
the muscles. The physiological cross-section areas of the according
muscles of the investigated dogs were significantly different in
size. This is probably due to the different constitution of the
dogs, in both the nutritional status and the condition. In the
second part of the study the vertical and horizontal net joint
forces and the moments of the limbs joints in a German Shepherd
were analysed with the invert dynamic model. In order to determine
the forces and moments, the data of the gait analysis coupled with
the ground reaction forces and the inertial parameters of the
individual limb segments were necessary. Furthermore the
displacement of the superficial markers, which were attached to the
skin were measured during the gait analysis. The net joint forces
are greater in all of the joints of the forelimb than compared to
those in the hindlimb. When the vertical net joint forces were
taken into consideration the forces of the forelimb were even twice
has large. Due to the positioning of the body’s centre of gravity
closer to the forelimbs, these carry a greater load, which explains
the greater forces in the joints of the forelimb. The horizontal
forces in both limbs show a biphasic course. The time interval of
the decelerating and accelerating forces are near to the same size.
It also appears that the forelimb seems to slightly slow down the
forward motion, as the decelerating forces are greater than the
accelerating forces. The moments are also greater in the forelimb
than in the hindlimb.