Ch 74 Gait analysis Flashcards
Define Kinetic gait analysis and kinematic gait analysis
force plate = kinetic
Kinetic gait analysis: Study of forces generated during movement
Kinematic gait analysis: The study of motion irespective of masses or forces
Which gait are symmetric and asymmetric?
Symmetrical: walk, trot, pace
Asymmetrical: Canter, transverse gallop, rotary gallop
What are the 2 main phases of the gait cycle?
Stance phase
Swing phase
What is the ground reaction force?
The resultant force of all local forces acting on the foot/paw
What are the 9 quantites calculated for each foot fall on a force plate?
Which are most commonly used for analysis in dogs?
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
How do you calculate weight?
Weight = mass(kg) x acceleration of gravity on earth (9.81m/s^2)
What do the vertical force Fz and the craniocaudal force Fy represent?
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)
What is the impulse value?
The area under the forse-time curve and takes both force, and contact time into consideration
What change is expected regarding peak vertical force and impulse value with pain or lameness?
Both are reduced
What is represented by the rising and falling slope of a force-time curve?
What changes are expected with pain/lameness
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)
What number of photocells are required to measure velocity and acceleration?
Force Plate Systems
Velocity - at least 2 photocells
Acceleration - At least three photocells
Placed 0.5m above gait platform, 0.5 - 3m apart
How do you calculate velocity?
Distance traveled (m) / time (change in time) in seconds
How do you calculate acceleration?
Change in velocity (m/s) /time (s)
What are some of the main differences of pressure walkways as appossed to force plate?
- 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
During a trot, what is the average PVF of the thoracic limb and pelvic limb?
Thoracic limb 115% BW
Pelvic limb 72% BW
Which gait is the more sensitive and accurate for the detection of low-grade or mild lameness in dogs?
Trot - no overlap of footfalls
pressure walkways
- 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)
What is symmetry index?
The use of an animals own limbs to serve as an internal control for comparison
What is a normal level of asymmetry?
Has been repored as less than 3.2 or less than 6%
What are some common sources of variability? (5)
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
What are the three joint rotations and the three joint translations in kinematic analysis?
Rotations:
- Flexion and extension
- Internal and external rotation
- Abduction and adduction
Translations:
- Mediolateral
- Proximodistal “joint distraction”
- Craniocaudal “drawer”
What is parallax error and perspective error?
- Parallax error: subject moves away from the optical axis of the camera
- Perspective error: WHen subject moves out of calibrated plane of motion
What are the 2 forms of markers that can be used for kinematic analysis?
Passive markers: Circular/spherical, non-reflective markers
Active markers: Light-emitting diodes.
What point values are commonly assessed using kinematic analysis?
Range of motion
Maximal flexion or extension
List some forms of complete waveform analysis of kinematic analysis
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
Define forward dynamics and inverse dynamics
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
Define joint moment and joint power as it relates to dynamics
Joint moment - net joint torque acting around a joint
Joint power - measure of mechanical energy generation and absorption across the joint
The ultimate goal of kinematic gait analysis
sources of variation?
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
Recall Bias in Client-Reported Outcomes in Canine Orthopaedic Patients Using Clinical Metrology Instruments
Eirini Pappa 2023
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.
Evaluation of parameters obtained from two systems of gait analysis
ND Assaf,
AVJ
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.
Best practices for measuring and reporting ground reaction
forces in dogs
Conzemius 2021
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.
Validated owner surveys generate
important information but are influenced by a caregiver
placebo effect, are subjective, and are an indirect measure of the patient.
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
The Effect of Calibration Method on Repeatability
and Reproducibility of Pressure Mat Data in a
Canine Population
Javier Rincon Alvarez 2020
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.
