Page 46 - Canine Lameness

18 2 Objective Gait Analysis

Figure 2.3 Ground reaction forces, impulse values, and pelvic limb kinematics from dogs walking and
trotting.

athletics, where dogs undergo rapid directional changes, it is possible that evaluation may prove
valuable in the future.

While forces are the primary measurement of clinical interest in veterinary patients, FPs also
allow researchers to measure moments (Mz, My, and Mx) and to calculate the center of pressure
(COP; Figure 2.2). Moments are the turning effect of a force (e.g. “torque”). The COP is where the
vertical GRF is centered under the foot and has been used to evaluate balance in humans. Currently,
moments and COP are infrequently evaluated in veterinary patients.

2.2.3 Force Plate Systems: Clinically Reported Values
Peak Force – This is the maximum force (Fz, Fy, and Fx) and is graphically represented as the
peak or “top” of the force curve (Figure 2.3). The vertical force (Fz) has one peak referred to as
the peak vertical force (PVF). The craniocaudal force (Fy) is biphasic and has a peak braking
(PFy braking ) and peak propulsive force (PFy propulsion ). Reduced peak forces are associated with
lameness. These are the most commonly reported and compared values.
Impulse – The impulse of any GRF is the product of that force and stance time and is simply the
area under the force‐time curve (Figure 2.3). The vertical impulse (VI) (Iz) is a single value and
the craniocaudal impulse (Iy) is separated into braking (Iy braking ) and propulsive (Iy propulsion )
components. Reduced impulses are associated with lameness.