LT/LH and Club Foot - same theories?

I've noticed many people use the same theories on Long Toe / Low Heeled horses as they do with club feet. Such as frog support and setting shoes back.

What is the reasoning behind doing the same thing for completely opposite conformations?

Lets try to keep this as a static balance question. There's enough variable in static balance, variable including dynamic get excessive!

Only need to buy one brand of shoe.

The same exterior applications may effect different interior structure. Nice thick strong heels on a club may hold the frog away from ground surface support and a frog support system can act as a frog extension, easing the load on the heels and interior structures.
A LTLH foot with crushed frog and heels can use the same set up to protect and support the heels and frog.
On each type of foot you'll get toe distortion, but for different reasons, and an eased breakover may help reduce the stresses that cause the distortion.

Bill, any chance of explaining that without using the term support?

Anytime I've seen crushed heels and frogs there's also compression of the soft tissues structures. If you are decreasing stress on the heels then you must be increasing stress to the already compressed soft tissue structures?

Can you be more specific as to eased breakover? Rockering the toe is eased breakover and reduces forces to the flexor. Setting the shoe back reduces forces to the flexor and also puts the weight of the horse on a smaller surface area. I'm not sure why on a LTLH which has compressed soft tissue you would want to add the weight of the horse to a smaller surface area or reduce force to the flexor? I can understand why you might want to do that to a club foot.

I edited the first post to keep this discussion mainly pointed to static balance.

I use the term support to differentiate from pressure. Support good, pressure bad.
On a LTLH front foot with crushed heels, frog and a perimeter fit narrow web shoe (or barefoot), the shoe can add pressure to the heels and the long toe will ad stress to the flexor (at the point of stride where the heels come up) which adds compression to the soft tissue.
Applying a frog support pad, possibly with elevation, soft impresion or Equithane, and a wide web shoe held back a bit with a rolled toe, offers protection, and equal support of the whole foot. The relieved breakover eases stress from the flexor which I'm willing to trade for loss of solar area in the toe that's protected by that wide web and pad anyway.

Let me go ahead and kick this hornets nest...and by all means, don't take my word for it, read the references at the bottom.

A phenotype of club foot is a result of excess DFT tension. When looking at the bottom of a club/high type foot we see that the wall, even though the actual length of toe may appear short, is far ahead of the apex of the frog when compared to a low foot. With the low foot (on a high/low), even though the actual length of toe may appear long, the distance from apex to the outer wall at the toe, is comparatively shorter.

Due to the spatial orientation of the solar surface of the foot, the theoretical 'pressure point' (net GRF vector) will be found more toward the toe in the high foot and comparatively more toward the heel in the low foot.

In the A/P plane, the forces causing moments about the COA are balanced by two components, the flexor moment and the extensor moment. The flexor moment is the product of the distance from the COA to the center of the flexor tendon over the navicular bone (this distance is the 'flexor lever arm') and the tensile force in the DFT. The flexor moment is balanced equally and oppositely by the extensor moment. The extensor moment is the product of the net GRF on the foot and the distance from its vertical locale to the COA (this distance is the 'extensor lever arm').

Hypothetically, if we add a toe extension (in a deformable substrate) or toe wedge, or both, these things move the pressure point forward in the foot. By doing so, it does not change the magnitude of the GRF, it does change its location...by moving it forward. In moving the pressure point forward, it increases the extensor lever arm, which when multiplied by the net GRF, increases the extensor moment. Consequently, this scenario requires more tension in the DFT (since the flexor lever arm is essentially a fixed distance, flexor force is the variable).

Hypothetically, if we add a heel extension like an egg bar shoe (in a deformable substrate) or a heel wedge, or both, these things move the pressure point rearward in the foot. By doing so, it does not change the magnitude of the GRF, it does change its location...by moving it rearward. In moving the pressure point rearward, it decreases the extensor lever arm, which when multiplied by the net GRF, decreases the extensor moment. Consequently, this scenario requires less tension in the DFT.

I don't think either of these two scenarios will raise any eyebrows. How about a bar shoe and or heel wedge on a club foot? Probably still not raising any eyebrows.

However, with the exact same knowledge of moments about the COA and how the pressure point is manipulated, what happens when, instead of focusing on the flexor apparatus, we consider soft tissues? If a horse has a soft tissue injury...lets just say a crushed heel...what happens when we apply an egg bar or wedge? What happens when we set a shoe back on that foot? ...it moves the pressure point back toward that crushed heel.

Doesn't it seem absurd to consider setting a shoe forward, adding a toe extension, and/or toe wedge to a club type foot? (unless you are one who believes you can stretch a tendon...I always thought stretched tendons were called bows).

Using the exact same reasoning and physics, why is it not absurd to set back, add a bar, and/or heel wedge on a low foot? The physics doesn't change.

Arguably, manipulating the pressure point has different ramifications for different aspects of the anatomy (tendons, soft tissue, bony column, etc.) and I don't know if I will be putting toe wedges on those low feet with crushed heels any time soon, but it does paint the picture in a whole new light and gives rise to a whole new set of unanswered questions...

Parks, Andrew. Therapeutic Farriery: One Veterinarian's Perspective, Vet Clin Equine 28 (2012) 333-350.

Parks, Andrew. Aspects of Functional Anatomy of the Distal Limb, AAEP proceedings (2012).

The second reference above can be viewed at: http://www.equipodiatry.com/AspectsofFunctionalAnatomyoftheDistalLimb.html

Scruggs; I have been putting barshoes on club feet for years (1990's)...[it works] before; and STILL vets and other farriers think it is wrong to do; and what is high is low and what is low is high. look at the shoulders of the horse with a H/L; the muscles? shoeing with a barshoe does not change it; but it does make the horse more comfortable in it's back and shoulders. Parachutist was a great example of this; have old pics of this stallion's feet, if I can find them. an old racetrack trainer and horseman taught me a long time ago; when it was done back in the early 30's-60's. I shod his old stallion like that. it has it's merits.

ps: I will be shoeing a horse like that today...............in the snow

Linda, I could be wrong but I don't think you putting barshoes on club feet since the 90's really explains your theory.

Just trying to narrow down the subject. Feel free to add dynamic balance to it if you want.

This was my main point of making this thread. Many theories sound good until you break them down a bit, then they really don't make a whole lot of sense.

setting shoes back on negative angled horses, adding shoe out the back to support a heel, positioning shoes so they are center below coa........

Reverse engineering is fine but you should still be able to explain what it is you are doing.

The bone and hoof capsule may change but the physics will not.

I think it's fairly obvious that on a club foot, trimming the heels low or adding an anterior extension increases force to the flexor moment? When it comes to a negative angle we can't just change the rules and suggest setting the shoe back also increases force.

your right Eric, all I know is that an old racetrack trainer who's in his late 70's now; who shod horses let me know of this; and it does help; why I have no answers except it does seem to give comfort to the horse.

Some food for thought - comparison of centers between normal (first image) and club foot (second image).

Tom - Why does that red line keep moving back as the angle is increased? I thought Duckett's Dot was the mechanical center of pressure (GRFV)?

I see the same thing on the link Scruggs posted but I don't understand it.

Nope. Where did you get that silly idea? It is the center of WEIGHT bearing.

GRF opposes WEIGHT.

Weight pushes DOWN.

GRF pushes UP.

The center of GRF moves in opposition to the center of weight bearing (Duckett's Dot) as the center of gravity of the horse moves during weight bearing.

If you have ever seen Pat Reilly's force plate experiment videos where the center of pressure moves as the horse passes over the foot during stance, you are seeing the center of GRF move in response to the horses's weight moving over a FIXED POINT - Duckett's Dot.