Need to freshen up the blog as it has been a while since adding information here. I have been playing with different mapping protocols to help find the center of rotation of the coffin joint. I first heard of the golden means ration from Craig Trnka and Scott lampert. I will admit it sounded a little fishy at first but after playing with it for a few years it is amazing how many things in life follow this proportional developent. Follow the link below to learn more.
GOLDEN RATIO
Basically the coffin bone follows closely a proportional development. Once you can identify the tip of p3 and the wings you can then use a golden ratio caliper to find a point that is very close to the mechanical center of rotation of the coffin joint. It has long since been known that managing the forces around the coffin joint are very important and identifying this point on the foot surface can be very consistent. It correlates well with other reported mapping protocols. It commonly lines up with the trimmed bars and widest part of the white line.
Wings can be located very close to the angle of the sole. It is more accurately place at the stratum internum where the bar turns in at the heel. Then carry a line towards the toe very close to parallel to the central sulcus. Where this point crosses the white line will also be very close to the tip of the coffin bone. I confirm this with measuring a thumbs width in front of the apex of the frog. Using the golden means caliper place the short side at the heels and long side at tip of coffin bone. The center point of the caliper will be very close to the center of rotation of the coffin joint. This point will often line up very close to the insertion of the deep flexor tendon as well. A line dropped perpendicular to the wings of the coffin bone and centered on the center of rotation will cross this point on the ground surface of the hoof.
Note the thumb tack and its alignment to the center of rotation of the coffin joint. Also note the barium marking the point located on the heels that corresponds to the wings. In sound young horses with no lameness or pathology I would strive to balance the leverages around this point. Often times a rockered rolled toe is all that is needed. Many coffin bones and hooves have such long toe levers it is impossible to provide even toe and heel levers. One cannot leave excessive heel length as it is a hazard and can act a lever that could lead to a crushing of the horn in the heel. In these case I recommend placing the toe lever as far back as the tip of the coffin bone and adding modifications to the ground surface that improve ground interaction. A combined rolled toe with concaved inner rim and a fullered heel branch will encourage the toe to sink and the heel to float. This will aid in prevention of heavy tendon load and hyperextension of the coffin joint.
GOLDEN RATIO
Basically the coffin bone follows closely a proportional development. Once you can identify the tip of p3 and the wings you can then use a golden ratio caliper to find a point that is very close to the mechanical center of rotation of the coffin joint. It has long since been known that managing the forces around the coffin joint are very important and identifying this point on the foot surface can be very consistent. It correlates well with other reported mapping protocols. It commonly lines up with the trimmed bars and widest part of the white line.
Fullering the branches behind the COR and concaving in front helps with the interaction of the hoof in soft footing. This could very easily be a maintenance shoe for a young horse in training. This may help delay lameness that often occurs with performance from chronic low grade overload of the deep flexor tendon, navicular apparatus and coffin joint. If lameness exist a much greater mechanical advantage will likely be needed to unload and manage an already painful system. Bar shoes are one very effective way to balance out the sink/flotation aspect of hooves with excessive toe levers. Commonly I use these ground surface modifications combined with wedges that are fully rockered from toe to heel.
Wishing you the best of the best!
Thanks for reading.
Sammy