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Objective Evaluation of Lameness (in horses) Using Body-Moun

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kevin keegan

on 25 August 2015

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Transcript of Objective Evaluation of Lameness (in horses) Using Body-Moun

Objective Evaluation of Lameness (in horses) Using Body-Mounted Inertial Sensors
Kevin Keegan
University of Missouri

The Need for Objective Lameness Evaluation?
Inertial Sensor Systems for Lameness Evaluation in Horses
(available, or soon to be)

Inertial Sensors
MEMS (i.e. they are small)
low power consumption
programmable
cheap
AGENDA
1. Objective Lameness Evaluation - WHY?
2. Kinematics via Inertial Sensors - WHY?
3. Some Systems that are Available
4. One system in depth - The one I know
5. Other possibilities

How Good is Subjective Evaluation?
No machine that gives accurate objective data is going to replace the experienced veterinarian or lessen his/her importance
We are biased
We have limited temporal resolution, so...
We missed things that happen very rapidly.
There is evidence of poor agreement between experts
What is Lameness - Levels of Definition
1. Lameness as a Clinical Sign
2. Lameness as a Etiology/Pathology
3. Lameness as Something to Treat
Measuring Lameness (as a clinical sign) is much harder than measuring other clinical signs of other diseases
-it's VARIABLE!
day to day
stride to stride
Lameness as a Clinical Sign
-This is really a measurement problem
Camera/Marker/Video Kinematic Analysis for routine lameness evaluation
too difficult
limited

force plate
Advantages
high sensitivity
high precision
can measure orthoganal forces
Disadvantages
difficult to use
non-portable
limited number of strides
force-measuring horses shoes
Kai, Aoki, Hiraga, et al (2000)
Advantages
multiple strides can be collected
University of Zurich
accelerometers
gyroscope (angular rate)
INERTIAL SENSORS
Equimetrix (Centaure Metrix)
http://www.centaure-metrix.com
EquuSys
(USA - Massachusetts)

Pegasus
(UK)
Advertised as a "gait analysis" system
Different products
Limb Phasing
Cannon and Hock angle
stride rate (discontinued)
Royal Veterinary College
(Equigate)
Used MTx sensors from XSens
9-degrees of freedom
3 accelerometers
3 gyroscopes
3 magnetometers
proprietary extended Kalmin filer (sensor fusion) algorithm
53mm x 38mm x 21mm, 30 g
we collaborated with computer engineers
this is a data mining problem
Go collect lots of data!
on many horses
on sound horses
on lame horses
natural lameness
induced lameness
all the information you need to detect and differentiate (left from right) lameness you can find in vertical motion of the torso.
Vertical motion of the torso is the most sensitive indicator of lameness
We did not know what to measure.....
max, min, area under curve, frequency?
VPM
RPM
The evidence is stronger
toe vs heel lameness
11 out 14 horses with heel lameness had higher mindiffpelvis than maxidiffpelvis
mean maxidiffpelvis higher for toe lameness
mean mindiffpelvis higher for heel lameness
VALIDATION
INERTIAL SENSORS ARE REPEATABLE
FORELIMB
LL picked correct limb first in 63.3% of trials
Evaluators picked correct limb first in 3.3% of trials
HINDLIMB
LL picked correct limb first in 80% of trials
Evaluators picked correct limb first in 13.3% of trials
This is a legitimate criticism, but...
fault detection is not based on measuring the exact amplitude of vertical head or pelvic motion
inertial sensors have equaled or outperformed experienced subjective evaluators at picking up lameness
No sensor adjustment needed under 17 degrees of rotation
Maxdiff - LOA
33 mm (4.7 mm +/- 3.6 mm)
21 mm (3.3 mm +/- 3.1 mm)
11 mm (2.4 mm +/- 2.6 mm)
5 mm (1.5 mm +/- 2.3 mm)
0 mm (0.9 mm +/- 2.0 mm)
Maxdiff - LOA
33 mm (1.4 mm +/- 3.9 mm)
18.9 mm (1.4 mm +/- 4.1 mm)
6.2 mm (1.4 mm +/- 4.3 mm)
0 mm (1.4 mm +/- 4.3 mm)
All thanks go to the collaborators
Yoshiharu Yonezawa PhD
Hiroshima Institute of Technology
P. Frank Pai PhD
University of Missouri
Hiromitchi Maki PhD
Hiroshima Institute of Technology
Detail 4
ACVS Laboratories - October 23, 2013 (San Antonio, TX)
Beginning
Advanced
4 hours approved CE credit
Torso mounted inertial sensors give the vet 3 pieces of information
limb/limbs involved
severity
timing of lameness (impact vs pushoff or both)
RF
LH
RAYS LONGER
LEFT FORELIMB LAMENESS

with
compensatory
right hind
RIGHT
HIND LIMB
LAMENESS

with
compensatory
right front
mild
left front

with
compensatory
right hind
mild
right front
mild
right hind
Evaluation of lameness while lunging
compare lunge left to lunge right
Evaluating flexion tests
A1/A2
A1/A2
RIGHT
A1/A2
LEFT
LAMENESS
PLOTS
MINDIFF
(MEAN/SD)
MAXDIFF
(MEAN/SD)
DOUBLE INTEGRATION
ERROR CORRECTION
CURVE FITTING/ERROR CORRECTION
FIRST THINGS FIRST
skeptical???
this equipment does not replace you
this equipment will help you
this equipment is easy to use
this equipment can make you money
(my) clients like it when I use this equipment. In fact the have come to expect it.
THE ALGORITHMS ARE DESIGNED TO EVALUATE THE TROT.
HOWEVER, ANY SYMMETRICAL
2- OR 4-BEAT GAIT CAN BE COLLECTED AND ANALYZED
YOU HAVE TO LEARN HOW IT WORKS
Lunging Horses and Hind Limb Lameness
Lunging masks hind limb lameness
soft ground
inside hind limb impact
outside hind limb pushoff
hard ground
inside hind limb impact and pushoff
Equimetrix
Equusys
Pegasus
Equigate
Gaitcheck
Equinosis
Gaitcheck
(NDI)

gives a number (1-4) for each sensor
health of gait
sold to anyone
range 20 m
????????????
One system (in depth)
why put the inertial sensors on the torso?
Early on, we did not know what to measure
We collaborated with mechanical engineers
(good signal processors)
this is a fault detection problem
Type of Frequency Analysis
Vertical torso movement modeled as a surface vibration
Perturbation of normal movement
from lameness
fault detection equation
The "shape" of the summed components gives information about the timing of the lameness (i.e. impact vs pushoff)
Limbs, Head, Joints,Torso?????
Head nod in the normal horse
Keegan KG, Yonezawa Y, Pai PF, Wilson DA. Telemeterized accelerometer-based system for the detection of lameness in horses. Biomedical Science Instrumentation 38 (ISA [International Society for Measurement and Control volume 419]:112, 2002).
weight of sensors = 30 grams
size of sensors = 3.5 x 3.4 x 2 cm
range of transmission = 100 m
live data collection
3 minute setup
analysis and reporting takes seconds
should not interfere with normal lameness evaluation
University of Glasgow
Evaluate the effectiveness of blocks
Evaluate Multiple Limb Lameness More Objectively
(the Law of Sides)

Allen Lee
(Leap Consulting)

there was an 89% improvement in the RH pushoff component
there was a 62% improvement in the RH impact component
Function of the ramus communicans of the medial and lateral palmar nerves of the horse. EVJ 2013.
Use of a wireless, inertial sensor-based system to objectively evaluate flexion tests in the horse, JF Marshall, DG Lund and LC Voute, EVJ 2012
Auburn University
1st wireless prototype
I don't need equipment like this!
This equipment is not for you!
This equipment takes away from the "art" of Lameness Evaluation, it supplants the veterinarian!
This equipment is sold only to licensed, practicing equine vets
You are still the boss!
Clients appreciate the objectivity, the added step. They will pay for the service.
New Developments
instrumenting the rider
measuring the influence of the rider on lameness
rider sitting trot
rider posting on left limb
measuring lameness at the canter
measuring lameness at the gallop (grayson Jockey)
SOMETHING NEW
FORCE MEASURING HORSE BOOTS
completely wireless
http://www.equusys.com/
http://pegasus.uk.com/wordpress/
http://www.equigait.de/
Dr. Marco Lopes
Thanks for listening
Full transcript