Gulliver: coffin bone fracture impacting LF

Moderate push-off and impact asymmetries in the left front 

The analysis shows moderate asymmetries, both in the push-off and in the impact phase. The horse is not applying as much force or weight on the left front limb when it comes into contact with the ground (impact asymmetry) and also not using it as strongly to push off from the ground (push-off asymmetry), compared to the right front limb. 

Quantified asymmetries 

In the individual strides section, the asymmetry is quantified as 1.1 (with a standard deviation of 0.3) in the push-off phase and 1.5 (with a standard deviation of 0.3) in the impact phase. There is also a very mild asymmetry in the push-off phase in the left hind.

Consistency

The lameness shows a very consistent pattern in the left front; all strides are clustered together, and the amplitude of the asymmetry (illustrated by the length of the lines) is moderate. In the hindlimbs there is also a very consistent asymmetry, but of a very low amplitude.
One outlier is seen in the hindlimbs, in the right-hand push-off quadrant.

 By assessing the slow-motion analysis video and data simultaneously, we can see that this outlier is caused by the first stride after turning the horse to trot away from the camera the second time.

 Data quality assessment

Longeing data is collected in two separate recordings, one for each direction on the circle. 

For the combined analysis, 33 front limb strides and 20 hind limb strides have been included for the left hand circle.  For the right hand circle 38 and 27 strides have been included for the front and hind respectively. The variation noted between these strides is “medium”, which is acceptable given the number of strides included. For the hind limbs, fewer strides have been included but the variation between strides is low, making the total result reliable. 

Notable issues on the left front 

The combined analysis shown at the top shows a clear asymmetry on the left front. 

The directional analysis shows that the asymmetry is more pronounced on the left circle in the push-off phase. 

Head

From this horse’s history, we know that it typically shows an inside impact asymmetry on the soft circle regardless of direction. 

However, now the horse shows an impact asymmetry pointing towards the left on both hands. Additionally, there is a left-front oriented push-off asymmetry in both directions, although most prominent on the left circle.

The gait analysis circle graphics for longeing analysis give a visual presentation of the combined analysis result in the larger circle at the top. The smaller circles at the bottom show you the analysis for the left-hand circle and the right-hand circle, respectively.

Hind

For the hindlimbs, there is a mild left hind asymmetry visible on the left circle. This mild asymmetry differs from the typical inside impact and outside push-off asymmetry observed in horses on the soft circle.

Diagnostic analgesia 

After the abaxial nerve block on the left front, the orange left front limb changed into a yellow limb and the the arrow up disappeared, meaning the asymmetry decreased and the push-off component disappeared. 

No further blocking was performed due to the clear improvement and the anamnesis of a chronic lameness.

After: measurement after block

Data comparison 

Quantitatively, there’s a significant improvement of 79% in the push-off and 62% in the impact component of the asymmetry in the left front after the abaxial block compared to baseline. The push-off asymmetry decreased from 1.1 to 0.2 (with a standard deviation of 0.2) and the impact asymmetry decreased from 1.5 to 0.6 (with a standard deviation of 0.3).

In the gait analysis circle graphics, we can clearly see that the stride-to-stride variation in the front increased while the amplitude of asymmetry decreased following the abaxial block. This is illustrated by the lines pointing in multiple directions instead of being clustered together closely. An increasing stride-to-stride variation is often seen when horses are trotted up following a positive block.