AN INERTIAL MOTION SYSTEM FOR THE EVALUATION OF HORSE MOTION IN FIELD CONDITIONS. PRELIMINARY REPORT

Transcription

1 AN INERTIAL MOTION SYSTEM FOR THE EVALUATION OF HORSE MOTION IN FIELD CONDITIONS. PRELIMINARY REPORT *Antonio M. Cruz DVM, MVM, MSc, DrMedVet, Dipl. ACVS, Dipl. ECVS, Dipl. ACVSMR # Diana Hodgins BSc, PhD, Dsc, MBA *Eric Martin DVM *Paton and Martin Veterinary Services Vancouver, British Columbia, CANADA #European technology for Business Ltd., Hertfordshire, UK. 8 th International Symposium on Veterinary Rehabilitation / Physical Therapy and Sports Medicine

2 CONFLICT OF INTEREST Diana Hodgins represents ETB the developer, marketer and manufacturer of the presented system. Paton and Martin Veterinary Services have no financial interest in the product nor in ETB.

3 INTRODUCTION Lameness is a very important problem Lameness is a movement asymmetry between the two stance phases of a pair of limbs (Pfau 2011) Lameness indicators: head nod, hip hike, fetlock drop and difference in stride length (Ross, Dyson 2011) Subjective visual evaluation is a poor tool in some occasions Nature looks for symmetry and in chronic lameness identifying asymmetry becomes difficult Compensatory mechanisms: Redistributing load by unloading affected limb or altering event timing during movement

4 INTRODUCTION Research has revealed that even amongst experienced veterinarians major differences in opinion occur about whether the horse is lame and on which limb (Fuller et al., 2006; Hewetson et al., 2006; Keegan et al.,1998, 2010; Pleasant et al., 1997; Starke et al., 2013 Prevention or early detection

5 Gait analysis tools BACKGROUND Kinetic (Force, acceleration, Energy, Work) Force plate Strain Gauges Pressure mats (Tekscan) Accelerometers Kinematics (Linear and angular motion) Optic systems Inertial motion units (accelerometers / gyroscopes)

6 OBJECTIVES This is a preliminary study Assess the feasibility of conducting gait evaluations in the field, ease of use and determining parameters in sound horses

7 MATERIALS AND METHODS IMU SENSORS 6 Inertial sensors 1 GPS Laptop Systems: Limb phasing Cannon angle Hock angle Fast and objective parameters in the horse s own environment

8 MATERIALS AND METHODS Limb phasing Horse s stride pattern Stride duration and length Speed, gait GPS Temporal limb phasing to the reference limb Cannon angle Sagittal plane: Protraction and Retraction Coronal Plane: Abduction and adduction Hock angle: Flexion / Extension

9 MATERIALS AND METHODS Sensors 54 grams 100 measurements/sec Tri-axial 5g Accelerometers Orthogonal 1200 deg/s gyroscopes x 3 Precision clock Memory storage device

10 MATERIALS AND METHODS Post Processing Software Pegasus 4.0

11 MATERIALS AND METHODS Horse selection 20 Warmbloods of varying sex and ages Sound by determination of veterinary evaluation

12 MATERIALS AND METHODS Procedure Sensors time stamped and synchronized and placed on boots Sensors calibrated by sitting still 10 secs after placement

13 MATERIALS AND METHODS Horse jogged in straight line at consistent speed on hard surface for 60 steps. Sensors are then removed from boots and attached to computer where software system extracts data and provides selected output

14 MATERIALS AND METHODS Data Processing Data stream of 10 coherent strides were used Variables measured: 1. the range of motion in degrees referring to the sagittal angles 2. the medial lateral movement in degrees referring to the coronal range 3. the symmetry which is the percentage difference in the sagittal range between left and right limbs 4. the timing at the following four time markers: A = Max. retraction of hind cannon B = Max retraction of tibia C = Max retraction of fore cannon D = Max hock angle in swing E= Max protraction of hind cannon F= Max protraction of fore cannon G= Max protraction of tibia H= Min hock angle at end of swing I=Max hock angle in stance J=Min hock angle at end of stance The values for timing are quoted as average and equal the percentage of the stride that the time marker occurs.

15 RESULTS Time to install including 4-7 minutes Time to process data 3-5 minutes Speed of horses ( m/s)

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17 Saggital Range of Motion Range Hock Range Tibia Range Cannon Fore Range Cannon HInd Left Right Left Right Left Right Left Right Mean SD

18 Coronal (medio lateral) Range of Motion Range Tibia Range Cannon Fore Range Cannon HInd Left Right Left Right Left Right Mean SD

19 Percentage difference of symmetry Asymmetry Hock Asymmetry Tibia Asymmetry Cannon Fore Asymmetry Cannon Hind Mean SD

20 TIMINGS A B C D E F G H I Mean SD A = Max. retraction of hind cannon B = Max retraction of tibia C = Max retraction of fore cannon D = Max hock angle in swing E= Max protraction of hind cannon F= Max protraction of fore cannon G= Max protraction of tibia H= Min hock angle at end of swing I=Max hock angle in stance J=Min hock angle at end of stance

21 RESULTS Problems encountered Charging problems Not allowing still time for static region to be found by sensor. Looseness on boots

22 DISCUSSION Ease of use Amount of information obtained Interpretation requiring skill Lack of direct studies Creation of a traffic light system Reliability Use as a monitoirng system for gait health Comparison to other systems

23 ACKNOWLEDGEMENTS To participating clients To Robyn Trelenberg, Andrea Dawson, Drs. Rachel Hector and Esther Millares

24 A B C D E F G H I Mean SD