Kapitel 74 - Gait analysis

Question 1

Define kinetic gait analysis and kinematics gait analysis

Answer 1

Kinetics gait analysis = the study of forces generated during movement

Kinematics gait analysis = the study of motion irrespective of masses and forces

Question 2

What are the two main phases of the gait cycle?

Answer 2

The stance phase and the swing phase

Question 3

Which are the directional force vectors usually used to describe ground reaction force?

Answer 3

• The vertical force (Fz) (the largest force)
• Craniocaudal force (Fy)
• Mediolateral (Fx) (the smallest force)

Question 4

Describe the graf

Answer 4

The graph represents the ground reactive force in trot (nr. 1) and walk (nr. 2).
The red line is the vertical force (Fz), the blue line the craniocaudal force (Fy) and the yellow line is the mediolateral force (Fx). The area under the curves is the vertical impulse.

The craniocaudal force had two periods during the stance phase:
1. The braking (deceleration), which occurs at the beginning of the stance phase, when an animal is initially contacting the ground and a decrease in forward momentum is occurring. This is characterized by positive force values.
2. Propulsion (acceleration), which occurs later in stance during the time when the limb is pushing off and propelling the animal forward. This period is characterized by negative force values.

Question 5

What is the peak force and the impulse values? How are they interpreted clinically?

Answer 5

a. Peak force = the “maximum” force exerted in the respective direction
b. Impulse value = is the area under the force-time curve and takes both force and contact time of the limb into consideration.
c. the peak and impulse values produce a singular value for each limb. Both values are accepted as measures of function and as indirect measures of pain.

Question 6

What changes in braking and propulsive forces would you expect in cranial cruciate ligament insufficiency?

Answer 6

Both forces will reduce

Question 7

Describe the loading rate and offloading rate. How would you expect them to be in a lame dog?

Answer 7

a. The rising of the slope is the period of the initial contact to the max force and gives us a loading rate. A steeper slope represents a more rapid loading of weight on the limb, whereas a lower slope represents slower loading of weight.

b. The falling slope is the period from maximal force to when contact with the ground ceases = offloading rate. A steeper slope represents a more rapid offloading of weight on the limb, whereas a lower slope represents slower offloading of weight.

c. The rising slope is reduced, consistent with a more cautious initial placement of weight on the limb (reduced loading rate). The falling slope is increased, consistent with a quicker removal of weight from the limb (increased offloading rate).

Question 8

Give examples of kinetic gait analysis equipment

Answer 8

a. Force plate system
b. Pressure walkway systems.

Question 9

Briefly describe how force plate works.

Answer 9

Uses transducers to measure force, most commonly strain gauge or piezoelectric sensor transducers.
The measurement of patient velocity and acceleration while the patient traverses the force plate(s) is done with the aid of photoelectric switches, commonly referred to as photocells.

Question 10

What is one of the most substantial differences between the two systems?

Answer 10

Force plate systems allow for the recording of direct force in newtons (N) in three directions: vertical, crainiocaudal, and mediolateral.

Pressure walkways measure and report pressure only in the vertical direction because they are unable to measure pressure in shear directions (craniocaudal and mediolateral).

Question 11

What are the most common variables used to compare lameness between groups of dogs?

Answer 11

Peak vertical force and vertical impulse.

Question 12

What does static and dynamic trial mean?

Answer 12

a. Dynamic trial = Measurements while the animal is walking or trotting over the force plate (most common used in vet med)

b. Static = measurements when the animal is standing on a force plate and evaluates weight distribution during standing.

Question 13

How is the weight distributed in a normal dog?

Answer 13

60 % of the weight is supported by the thoracic limbs.

40% by the pelvic limbs.

Question 14

What is symmetry index?

Answer 14

a. It is the use of an animal’s own limbs as an internal control for comparison between limbs.

In dogs, normal locomotion is assumed to be symmetrical, and a lack of symmetry is associated with pathologic gait.

Question 15

What are the three translations described as during kinematic studies?

Answer 15

a. Mediolateral translation

b. Proximodistal (or joint distraction)

c. Craniocaudal (craniocaudal drawer)

Question 16

In two dimensional systems, thar are parallax error and perspective error?

Answer 16

a. Parallax error occurs as the subject moves away from the optical axis of the camera.

b. Perspective error occurs when the subject moves out of the calibrated plane of motion.

Question 17

What is Fourier, wavelet analysis and generalized indicator functions analysis examples of? Which one is most common used in veterinary medicine?

Answer 17

a. It is examples methods used for wave form analysis, allowing evaluation of gait data in wave form.

b. Fourier analysis is most commonly used in vet med

Question 18

Give examples of other methods of kinematic gait analysis

Answer 18

a. Radiostereometric analysis –> simultaneous orthogonal radiographs. Static with biplanar X-Ray methods or dynamic with fluoroscopy

b. Body-mounted inertial sensors (inertial measurement units) contain accelerometers & gyroscopes –> info on motion in 3D

c. CT/MRI (could potentially be used but low frame rate and restrictive environments are important limitations)

Question 19

What is inverse dynamic?

Answer 19

a. It is the use of available kinematic and kinetic data for the indirect calculation of forces and moments.

(opposite to forward dynamics which is the process of using forces and moments to directly calculate the resulting motion of an object)

Question 20

What are joint moments and joint power?

Answer 20

a. Joint moments are the net joint torque acting around a joint.

b. Joint power is a measure of mechanical energy generation and absorption across the joint.