Equine Results Interpretation Guide For Cannon Angles May 2013

Transcription

1 Equine Results Interpretation Guide For Cannon Angles May 2013 Page 1 of 20

2 Table of Contents 1. Introduction Options for all plots Tables of data Gaits Walk Trot Left canter Right canter CSV file header information Document History Version Date Changes 1 May 2013 Initial Issue Page 2 of 20

3 1. Introduction The ETB-Pegasus Cannon Angle software Poseidon enables users to measure the sagittal plane (protraction/retraction) and coronal plane (abduction/adduction) of the cannon over the time of a stride. This allows movement such as unequal flexion or dishing to be measured. Note: measurement accuracy depends to a degree on the correct alignment of the sensor on the leg. What you need to know about running a test The cannon angle system uses exactly the same hardware as the limb phasing system. Sensors set-up and mounting is the same, simply put the sensors into the brushing boot. When all sensors have been started the horse must stand stationary for 10 seconds. Then carry out the test as normal. Points to Remember: Sagittal plane refers to the plane that divides the right and left sections of the body. Any movement that occurs in this plane is in an anterior (ventral) to posterior (dorsal) direction. Coronal plane refers to the plane that divides the body into front and back. It is understood that any ideal, basic, gait should show minimal coronal plane movement. Page 3 of 20

4 The picture below shows movement in the sagittal plane. The fore limb is in protraction and the cannon angle results from this type of movement will be positive numbers. The hind limb is in retraction and the cannon angle results from this type of movement will be negative numbers. Page 4 of 20

5 -θ θ Sagittal Angle The picture below shows movement in the coronal plane. If the limb moves to the left the cannon angle results from this type of movement will be positive numbers. If the limb moves to the right, the cannon angle results from this type of movement will be negative numbers. Page 5 of 20

6 -θ θ Coronal Angle 1: An entire trial Page 6 of 20

7 2. Options for all plots A number of options have been made available to the user when analysing the angles in a typical stride. This is to enable better visualisation of how the horse is moving. Any number of the plots can be included in the final report. Y Scaling Scaling of the plots can be altered by the user. The default is auto-scaling, which maximises the size of the plot to the screen. However, if you want to compare plots then you may choose to fix the scale. Angles The default setting is for the sagittal plots to be plotted as relative values and the medial-lateral as absolute values. The user can change and plot all angles as absolute values. However, care should be taken when choosing this option as absolute angles requires the alignment of the sensor along the limb axis to be exact. For the relative values, where plots start from zero, the range will always be correct, whatever the starting value. Focus The default is to use the left hind as the reference and all the line markings are shown on the plots for the left hind and fore limbs. However, it is possible to change the focus to the right limbs and this will then move the lines to the points for the right limbs. Phasing Two options are available for walk and trot, which are both symmetric gaits. 50% phase In order to visualise the timing and the range of movement in the sagittal and coronal planes, one option is to move the right hind back by 50%. If the timing was exact then the left and right hind should sit on top of each other Best fit Alternatively, the right hind can be moved so that it has the closest fit to the left hind, which may be more or less than 50%. This option enables the viewer to see if the profile of movement is the same on the left and right side. Lines on the plots For all the plots there are a number of lines shown: A, B, C and D. A This is the maximum protraction position for the hind limb (plotted for left hind unless Focus is altered by the user to show the right hind). Page 7 of 20

8 B This is the maximum protraction position for the fore limb (plotted for left fore unless Focus is altered by the user to show the right fore). C This is the maximum retraction position for the hind limb (plotted for left hind unless Focus is altered by the user to show the right hind). D This is the maximum retraction position for the fore limb (plotted for left fore unless Focus is altered by the user to show the right fore). Colours for the plots In all the plots the colours are left blue, right-green. The time lines are shown in red. Sagittal plots The sagittal plots show the two hind limbs in the top plot. These are phase aligned for walk and trot, but not for canter or gallop. For more information on the phase alignment read the gait description. The next plot down is for the fore limbs. Again these are phase aligned depending upon the gait. Medial-lateral plots The medial-lateral plots are shown for the hind limbs and then the forelimbs. These are shown as absolute values as the sensor is fixed hard against the limb axis by the pocket and strap. 3. Tables of data For each set of saved data a set of values are produced in two tables. The first refers to the angle data. Range of motion is in degrees and refers to the sagittal angles. Medial lateral is also in degrees and refers to the coronal range. Timing is the percentage of the stride that the point occurs, and is quoted for both the left and right limbs. Symmetry is the percentage difference in the sagittal range between the left and right limbs. The table below is an example for walk. Page 8 of 20

9 Range of Motion Left Right Range cannon fore Range cannon hind Medial Lateral Cannon fore Cannon hind Timing A B C D Symmetry Cannon fore (%) Cannon hind (%) Walk Strides Time Dist. Total 13 0:16 Average Min. Max. Left fore Right fore Left hind Right hind Diagonal asymmetry Hind leg asymmetry Stride duration (s) Speed (m/s) Stride length (m) The second table relates to the overall stride characteristics over the region chosen. This provides the phasing information and the stride data. Page 9 of 20

10 4. Gaits 5. Walk Walk is a symmetric, 4 beat gait. Irrespective of the time it takes for the horse to complete a stride, when starting with one hind limb the other hind limb should move half way through the stride (50%). Similarly the fore limbs should be 50% apart in terms of timing. Also in walk the ipsilateral fore limb follows the hind limb, producing the 4 beat gait. In the plots the fore limbs have the same phasing as the hind limbs i.e the left fore does not have any shift introduced whilst the right fore has the same shift as the right hind. The starting point in the stride is where the hind is at the most protracted position. Page 10 of 20

11 In the plot shown the phasing has been chosen as 50%, autoscaling with the left focus and relative angles. It can be seen that the left and right hind have a similar angle profile through the stride and the phasing is close to 50 (the two plots overlay). The fore limb is at the most retracted point when the hind limb is at the most protracted point for the right and slightly apart for the left (A and D lines shown for the left side). The profile for the left fore is quite uneven when moving forward from the most retracted position and corresponds approximately to when the fore limb is going through the vertical position. Page 11 of 20

12 The medial lateral movement is similar for both fore limbs and both hind limbs and is not excessive. 6. Trot Trot is a symmetric, 2 beat gait. Irrespective of the time it takes for the horse to complete a stride, when starting with one hind limb the other hind limb should move half way through the stride (50%). Similarly the contralateral fore limbs should be almost in phase (hoof down should occur at the same time). In the plots the contralateral fore limbs have the same phasing as the hind limbs i.e the right fore does not have any shift introduced whilst the left fore has the same shift as the right hind. The starting point in the stride is where the hind is at the most protracted position. Page 12 of 20

13 In the plot shown the phasing has been chosen as 50%, autoscaling with the left focus and relative angles. It can be seen that the left and right hind have different angle profiles from maximum retraction to maximum protraction, but similar between maximum protraction and maximum retraction. This means that the phasing is not close to 50 (the two plots do not overlay). On the left side the hind moves forward in advance of the fore limb and then drops back before the fore limb has reached maximum protraction (line B). The ledge on the left Page 13 of 20

14 hind corresponds to where the right fore is at maximum protraction. Hooves down will also occur in this region. On the right hind the forward movement is much slower, indicating more of a dragging movement and the right hind only reaches maximum protraction at the same time as the left fore. The medial lateral movement is similar for both fore limbs and both hind limbs and is not excessive. 7. Left canter Left canter is not a symmetric gait, it starts with the right hind and the diagonal pair(left hind and right fore) should be coupled, with the left fore leading. For this reason there is no phase shift introduced. Page 14 of 20

15 In this example the right hind has less range than the left hind. The left hind and right fore are almost coupled and the left fore is at maximum protraction at about 80% through the stride (line B). The medial-lateral movement on all limbs is minimal. 8. Right canter Page 15 of 20

16 Right canter is not a symmetric gait, it starts with the left hind and the diagonal pair (right hind and left fore) should be coupled, with the right fore leading. For this reason there is no phase shift introduced. In this example the right hind has greater range than the left hind. The right hind and the left fore are coupled (in phase with each other) and the leading right fore is less than 80% through the stride at maximum protraction. When comparing the left and right canter, the range of motion and the timing of the movements (phase) are important. In this exxample the left and right canter differ in a number of ways. The point of maximum protraction (phasing) is less for each limb in Page 16 of 20

17 right canter compared to left. The range of the hind limbs is greater in right canter than left, and the diagonal pair are more closely couple in right canter than left. 9. CSV file header information Below is a detailed description of all of the headings used in this file. The information recorded on the trial is saved in a standard CSV file. This file can be used and imported into a number of programs once the data has been manipulated to suit your application. Below is the description of the data construction of the CSV headers. Note the values shown in the Poseidon Application have been manipulated. The information below informs you what the unit of value is for the particular number saved in the CSV file. There is mention of omitting rows and columns, what this means to the data in the CVS file is that there is none, no tab or comma s. [Preamble] Created by Poseidon Motion Analyser - Format type Title - Name given to the file Start Time - Number of seconds from 1 st January 1970 [Data] This is where all the data in the analysed file is stored. [Angle Data] This has 15 columns Time The time from the start of the analysis for every single reading in steps of approximately 10ms. Joint angles LT^LH The angle between the left tibia and hind in degrees. RT^RH The angle between the right tibia and hind in degrees. Sagittal Angles LF Angle of the left calf in degrees RF Angle of the right calf in degrees LH Angle of the left hind in degrees RH Angle of the right hind in degrees LT Angle of the left tibia in degrees RT Angle of the right tibia in degrees Coronal Angles LF Angle of the left fore in degrees RF Angle of the right fore in degrees LH Angle of the left hind in degrees RH Angle of the right hind in degrees LT Angle of the left tibia in degrees RT Angle of the right tibia in degrees [End of Data] Signifies the end of the recorded data [Gait Data] Time Where in the test the strides were selected. Stride Duration measured in seconds Page 17 of 20

18 Gait 0 = Unclassified, 1=Walk, 2= Trot, 3= Right Canter, 4= Left Canter, 5=Right Gallop, 6=Left Gallop, 7=Tolt, 8=Pace Limb Phasing LF Percentage difference, default is zero. RF Phase fraction, multiply by 100 to get the percentage. If zero the right hind was chosen as the reference. LH Percentage difference, default is zero. RH Percentage difference, default is zero. Speed Speed in metres per second Latitude Longitude Note: if the latitude and longitude values are plotted directly, the resultant plot will be as though you are looking up from the earth to the stars. If only gait has been analysed (no Pegasus-S used) then some columns will be omitted from the csv file. [EndOfData] End of chart data [Regions of Interest: x] The number of regions analysed. List of regions and the time within the test that they took place. Region "All" has no data other than start and end time. Other regions information is as follows. This is essentially the data to generate the curves that you see in the typical stride report. [Gait Statistics: x] Gait Gait classification number (see above) Strides Number of strides in the region selected Total Time Time in the region selected Total distance Distance travelled in the region selected For the following the data is as Median, Min, Max, also the list will vary depending on the type of gait selected. LF Phase percentage where it occurs during the stride RF Phase percentage where it occurs during the stride LH Phase percentage where it occurs during the stride RH Phase percentage where it occurs during the stride Diagonal Asymmetry % Hind Asymmetry % Stride duration Seconds Speed Metres/second Stride Length Metres [Joint Angles] [Typical Stride] LT^LH RT^RH [Mean plus Standard Deviation] LT^LH Page 18 of 20

19 RT^RH [Mean minus Standard Deviation] LT^LH RT^RH [Minimum] LT^LH RT^RH [Maximum] LT^LH RT^RH [Peak-to-peak] LT^LH RT^RH [Sagittal Angles] [Typical Stride] LF RF LH RH LT RT [Mean Plus Standard Deviation] LF RF LH RH LT RT [Mean minus Standard Deviation] LF RF LH RH LT RT [Minimum] LF RF LH RH LT RT [Maximum] LF RF LH Page 19 of 20

20 RH LT RT [Peak-to-peak] LF RF LH RH LT RT [Coronal Angles] Same data list as Sagittal angles [Summary: Region selected] Range hock (left,right) tibia (left,right) cannon fore (left,right) cannon hind (left,right) Medial Lateral Tibia (left,right) Cannon fore (left,right) Cannon hind (left,right) Timing Timing Timing Timing Symmetry% A (left,right) B (left,right) C (left,right) D (left,right) Hock Tibia Cannon fore Cannon hind Timestamps are in IMU ticks (1s/1024) and are normalised to zero from the start of the test. Angles are in degrees. Please note if you have done a long test covering over 15 minutes, some spreadsheet software programmes do not have the number of row capabilities to import the data. End of document Page 20 of 20