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Objective Evaluation of Lameness (in horses) Using Body-Moun
Transcript of Objective Evaluation of Lameness (in horses) Using Body-Moun
University of Missouri
The Need for Objective Lameness Evaluation?
Inertial Sensor Systems for Lameness Evaluation in Horses
(available, or soon to be)
MEMS (i.e. they are small)
low power consumption
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
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
can measure orthoganal forces
difficult to use
limited number of strides
force-measuring horses shoes
Kai, Aoki, Hiraga, et al (2000)
multiple strides can be collected
University of Zurich
gyroscope (angular rate)
Equimetrix (Centaure Metrix)
(USA - Massachusetts)
Advertised as a "gait analysis" system
Cannon and Hock angle
stride rate (discontinued)
Royal Veterinary College
Used MTx sensors from XSens
9-degrees of freedom
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
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?
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
INERTIAL SENSORS ARE REPEATABLE
LL picked correct limb first in 63.3% of trials
Evaluators picked correct limb first in 3.3% of trials
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
ACVS Laboratories - October 23, 2013 (San Antonio, TX)
4 hours approved CE credit
Torso mounted inertial sensors give the vet 3 pieces of information
timing of lameness (impact vs pushoff or both)
LEFT FORELIMB LAMENESS
Evaluation of lameness while lunging
compare lunge left to lunge right
Evaluating flexion tests
CURVE FITTING/ERROR CORRECTION
FIRST THINGS FIRST
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
inside hind limb impact
outside hind limb pushoff
inside hind limb impact and pushoff
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
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)
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
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.
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)
FORCE MEASURING HORSE BOOTS
Dr. Marco Lopes
Thanks for listening