Ch 74 Gait analysis

Question 1

Define Kinetic gait analysis and kinematic gait analysis

force plate = kinetic

Answer 1

Kinetic gait analysis: Study of forces generated during movement

Kinematic gait analysis: The study of motion irespective of masses or forces

Question 2

Which gait are symmetric and asymmetric?

Answer 2

Symmetrical: walk, trot, pace
Asymmetrical: Canter, transverse gallop, rotary gallop

Question 3

What are the 2 main phases of the gait cycle?

Answer 3

Stance phase
Swing phase

Question 4

What is the ground reaction force?

Answer 4

The resultant force of all local forces acting on the foot/paw

Question 5

What are the 9 quantites calculated for each foot fall on a force plate?
Which are most commonly used for analysis in dogs?

Answer 5

Three orthogonal components
- Fx, Fy, Fz - describes the direction of the force

Three spatial components
- x, y, z - describes the location of the force on the plate

Three orthogonal moments
- Mx, My, Mz

The direction of force is most commonly described, Fx (mediolateral), Fy (craniocaudal), Fz (vertical) with the vertical force Fz being most common

Question 6

How do you calculate weight?

Answer 6

Weight = mass(kg) x acceleration of gravity on earth (9.81m/s^2)

Question 7

What do the vertical force Fz and the craniocaudal force Fy represent?

Answer 7

Fz represents the vertical force of the leg and can be used to assed peak vertical force. Creates a bell chaped curve at a trot, M-shaped at a walk

Fy represents braking (positive value) and propulsion (negative value)

Question 8

What is the impulse value?

Answer 8

The area under the forse-time curve and takes both force, and contact time into consideration

Question 9

What change is expected regarding peak vertical force and impulse value with pain or lameness?

Answer 9

Both are reduced

Question 10

What is represented by the rising and falling slope of a force-time curve?
What changes are expected with pain/lameness

Answer 10

Rising slope depicts the loading rate of the limb and falling slope depects the offloading rate of a limb.
Pain/lameness:
- RIsing slope is reduced (less steep, slower to lad limb)
- Falling slope is increased (more steep, fast offloading)

Question 11

What number of photocells are required to measure velocity and acceleration?

Force Plate Systems

Answer 11

Velocity - at least 2 photocells
Acceleration - At least three photocells
Placed 0.5m above gait platform, 0.5 - 3m apart

Question 12

How do you calculate velocity?

Answer 12

Distance traveled (m) / time (change in time) in seconds

Question 13

How do you calculate acceleration?

Answer 13

Change in velocity (m/s) /time (s)

Question 14

What are some of the main differences of pressure walkways as appossed to force plate?

Answer 14

• Force plates calculate a direct foce in three directions whereas pressure walkway only calculates pressure in a vertical direction
• Pressure walkways can record infor for each individual limb, force plate only does one limb at a time
• Cannot compare one to the other

Question 15

During a trot, what is the average PVF of the thoracic limb and pelvic limb?

Answer 15

Thoracic limb 115% BW
Pelvic limb 72% BW

Question 16

Which gait is the more sensitive and accurate for the detection of low-grade or mild lameness in dogs?

Answer 16

Trot - no overlap of footfalls

Question 17

pressure walkways

Answer 17

• limited in their ability to assess force,
• strength may be in the easy and rapid collection of temporospatial parameters (stride time, stance time,, walking velocity, and the calculation of symmetry indices)

Question 18

What is symmetry index?

Answer 18

The use of an animals own limbs to serve as an internal control for comparison

Question 19

What is a normal level of asymmetry?

Answer 19

Has been repored as less than 3.2 or less than 6%

Question 20

What are some common sources of variability? (5)

Answer 20

Handler (low source)
Trial repetition
Habituation
Changes in velocity, stance time or acceleration/deceleration
Variation in dog

Variance in ground reaction forces data attributed to the dog ranges from 14% to 69%. The variance attributed to the dog has the greatest impact on peak vertical force

Question 21

What are the three joint rotations and the three joint translations in kinematic analysis?

Answer 21

Rotations:
- Flexion and extension
- Internal and external rotation
- Abduction and adduction

Translations:
- Mediolateral
- Proximodistal “joint distraction”
- Craniocaudal “drawer”

Question 22

What is parallax error and perspective error?

Answer 22

• Parallax error: subject moves away from the optical axis of the camera
• Perspective error: WHen subject moves out of calibrated plane of motion

Question 23

What are the 2 forms of markers that can be used for kinematic analysis?

Answer 23

Passive markers: Circular/spherical, non-reflective markers
Active markers: Light-emitting diodes.

Question 24

What point values are commonly assessed using kinematic analysis?

Answer 24

Range of motion
Maximal flexion or extension

Question 25

List some forms of complete waveform analysis of kinematic analysis

Answer 25

Fouriers analysis - can determine whether 2 gait cycles are similar. Deconstructs waveform into its component parts Wavelet analysis Generalised indicator function analysis - determines where in gait cycle the differences are occuring

Question 26

Define forward dynamics and inverse dynamics

Answer 26

Forward dynamics: The process of usinf forces and moments to directly calculate the resulting motion of an object Inverse dynamics: The use of available kinetic and kinematic data for the indirect calculation of forces and moments

Question 27

Define joint moment and joint power as it relates to dynamics

Answer 27

Joint moment - net joint torque acting around a joint Joint power - measure of mechanical energy generation and absorption across the joint

Question 28

The ultimate goal of kinematic gait analysis | sources of variation?

Answer 28

is to provide researchers and clinicians with a biologically accurate and clinically relevant method of evaluating musculoskeletal motion. sources of variation: - Skin motion artifact - Misplacement of markers - different researchers could affect kinematic gait data - patient

Question 29

Recall Bias in Client-Reported Outcomes in Canine Orthopaedic Patients Using Clinical Metrology Instruments Eirini Pappa 2023

Answer 29

longitudinal prospective cohort study of client-owned dogs poor agreement between different time points (t0 to T3 - 12 months), LOAD had moderate agreement for T0-1,2 - 2 and 6mths) Conclusion The LOAD and CBPI questionnaires are subject to recall bias. Studies reporting retrospectively acquired CMI data should be interpreted with caution.

Question 30

Evaluation of parameters obtained from two systems of gait analysis ND Assaf, | AVJ

Answer 30

orce platforms are considered one of the most accurate methods for kinetic gait analysis in dogs, since it allows the evaluation of vertical, mediolateral and craniocaudal ground reaction forces.1,2 However, some restrictions of using force platforms have stimulated the use and development of other gait systems, such as the pressure platform3–11 and, more recently, the Gait4Dog treadmill.12 Each gait system has limitations, but also advantages that must be considered depending upon the variable and animal to be evaluated. The gait parameters obtained from the Tekscan pressure-sensitive walkway and Gait4Dog treadmill revealed differences in the temporospatial parameters between systems, but similarity in body-weight distribution/ pressure percentage.

Question 31

Best practices for measuring and reporting ground reaction forces in dogs Conzemius 2021

Answer 31

Specific methodology, interpretation of results, and translation to clinical veterinary medicine have been inconsistent. GRFs in individual dogs with OA can wax and wane over a short period but a change greater than 5% is unusual and a change greater than 10% is rare. If an intervention provided a greater than 5% increase in both PVF and VI over a 2 month period in 75% of dogs, the reader knows that there is roughly a 65% chance that the dog they are about to treat with that intervention will benefit more than if the treatment was not used and a 5%-10% chance that a dog will change spontaneously.

Question 32

Validated owner surveys generate important information but are influenced by a caregiver placebo effect, are subjective, and are an indirect measure of the patient.

Answer 32

These same limitations exist with lameness and pain scores generated by a veterinarian; it has been shown that visual observation of gait is unreliable even by experienced observers

Question 33

The Effect of Calibration Method on Repeatability and Reproducibility of Pressure Mat Data in a Canine Population Javier Rincon Alvarez 2020

Answer 33

Although each calibration protocol yielded different PVF, VI and PP results in a heterogeneous group of dogs, the results were highly repeatable and reproducible for the individual calibration protocol.