Notes on the Statistical Data Shown in our Reports
The statistical distributions shown in our reports, and here on this page, are for front feet. To gather this information, we used tens of thousands of images from more than 60 veterinary clinics from around the world. Of these, our current report for the DP radiograph use data from about 5,000 unique hooves. We believe these are an accurate sample of the population of “horses radiographed by veterinarians”. Hence, the population includes horses with issues, but also images from pre-purchase exams, and images taken for shoeing/trimming purposes.
In the distribution graph, we color the central 70% of horses in green, and show 15% of horses with low lateral heel in red on the left, and 15% of horses with low medial in red on the right. Roughly speaking, we can say if the value falls in the green range, the measurement is ‘normal’ in the sense that it is in the range we observe for 70% of horses in our population. ‘Normal’ may differ from ‘Ideal’, but ‘Ideal’ is always more or less subjective. By showing actual measurements of a large number of horses, we get a feel for what is ‘Normal’, and our data is quite objective, and can be used by practitioners with varying belief systems.
Note that image-based measurements give a great evidence base for treatments but are not the whole story. These measures do not capture attributes of soft tissue (bruising, scars, etc) nor the details of the usage of the horse, or past medical history. All clinically relevant data should be used when diagnosing and treating.
Coffin-Joint Tilt
Our measure of ‘Coffin-Joint Tilt’ is an effective way to judge medial-lateral balance of the hoof. A green line is constructed to pass through the most distal points on the condyles of P2. This line is a good estimator for the orientation of mechanical joint axis of the coffin joint. Biomechanically speaking, it makes sense to have this rotational axis approximately parallel to ground. The ‘Coffin-Joint Tilt’ is the shallow angle this line makes relative to ground. A positive value means the medial heel is lower than the lateral heel, so the axis tilts in towards the medial side. A negative value means the opposite.
Our ‘P1 Alignment’ number is not an attribute of the horse, but rather it is a means to tell us if the x-ray apparatus was ‘lined up’ with the hoof and leg in a standard way. The ‘P1 Alignment’ value is how many degrees away from perpendicularity between the blue and green lines. A well-taken radiograph should have a small value of P1 Alignment. We suggest that if it is outside the range of +/- 3 degrees, the radiograph should be re-taken to get a better value for Coffin-Joint Tilt.
More details on the DP radiograph and our P1 Alignment scheme can be studied here.
Normal Range
The normal range encompassing 70% of horses in our population is from -0.9 degree up to 3.8 degrees with a median of 1.43 degrees. This means that the median Coffin-Joint Tilt for horses in our population is 1.43 degrees - so the medial heel is a bit lower than the lateral heel. In this sample image the hoof is lower on the medial side than average, but still within the central 70% of horses.