LT/LH and Club Foot - same theories?

The center is a single point. The weight bearing vector (a force in a direction) is vertical at this point and only at this point. The vertical line represents the direction of weight bearing at this single point.

If you support the foot on the ground with a single point, so the foot does not tip forward or backward, then you have cancelled all ground reaction force moments (leverage) and placed the ground pressure center point directly under the weight bearing center point.

When you add ground surface area forward of this ground surface point or behind this ground surface point, you change the ground force center on the ground, but the weight bearing center in the foot does not change. The weight bearing center remains the single point of convergence between changing ground force vectors and changing weight force vectors. This is why in force plate measurements the center of ground force pressure moves around as the horse moves. The center of ground force pressure as measured on a force plate usually wind up directly under the center of weight bearing at mid stance.

COP measured with force plates usually starts on the lateral heel at the loading phase of the stride, moves to a plumb line (or very close) from the center of weight bearing at mid stance, and moves off toward the lateral toe at breakover. This is ground force moving in reaction to weight force movement - again these forces converge in the center of P3.

my question must have been harder

David, I think of it like this; In a perfect foot the centers of the attachments of the Flexor and Extensor should be on a plumb line through the center of the bone when the philanges are aligned. Toe leverage ground forces are in front of the center of the bone, heel leverage ground forces are behind the center of the bone. The toe lever is shorter and distributes GRF on a shorter lever. The heel lever is longer and distributes less GRF on a longer lever.

In a club foot, the Flexor Tendon/Muscle unit is shortened, preventing alignment of the phalanges and , increasing the pull on the flexor and creating an abnormal moment on the toe. The weight bearing center moves forward, but at the same time the base length of the heel is shortened. So we lose heel support length and surface area do to a higher angle caused by tendon forces, and we increase toe pressure over a smaller area due to a short tendon.

In a broken back foot the weight bearing center moves back increasing heel pressure distribution over a smaller area due to a shorter heel support length in relation to the bone center. The toe pressure surface area goes up because the toe lever is longer due to the bone angle being lower.

If I set the shoe back on a club foot, I decrease the toe surface area and toe support lever. If when I set the shoe back, I also extend the heels, the shoe becomes a caudal ground force lever increasing heel pressure and subsequently the weight bearing distribution of the heels provides some relief to the weight bearing in the toe.

If I set the shoe back on a broken back foot, AND trim the heels back, and extend the heels of the shoe, I have redistributed ground forces back in the toe and the heel, decreasing toe GRF leverage, and increasing heel bearing area distribution.

It almost sounds like using the same solution on opposite problems. But it really isn't the same.

As in the standing horse? When the horse is not moving the center of weight bearing will be directly below the center of p3?

Well I'm still counting . . .

I can give you names and addresses for about 200.

Nope. Weight bearing center is the center of P3. Center of ground force pressure should be directly below the center of weight bearing in a standing horse, but I wouldn't expect it to be perfectly centered dead on a plumb line unless everything else was perfect.

The GRF center (pressure) will move slightly in stance as the horse shifts its weight even standing square and just moving its head to one side. This is not the sort of thing you can nail down with absolutes. It is not "how to shoe horses." It is just a way of describing the behavior of mechanical forces being exchanged between the horse and the earth during stance.

IDK, setting the shoe back and extending the heels sure sounds like the same thing to me.

In a club foot the Extensor Arm (ea) would already be longer than in a normal foot due to the force in the flexor creating a longer EA. Setting the shoe back would shorten the EA (parks)

In a broken back foot their would be less force in the flexor moment meaning a shorter EA. Setting the shoe back would shorten the EA more.

In a club foot, the normal hoof capsule issue is dishing at the toe. Decreasing the force to the flexor moment might be in order.

In a broken back foot the issue is generally the back half of the foot compressing. Decreasing force to the flexor would add to the problem. Not to mention setting the shoe back adds the weight to a smaller surface area half of which is already compromised. Better get the equipak out for that one!

We can likely argue positioning for eternity. Each change in position requires a different vector to use in the equation. Sometimes, however, arriving at an acceptable 'theta' is the most important aspect.

I thought the following diagram to be a quite befitting analogy of what is being discussed above. We all go about our daily routines from different angles and positions, but as long as we get within a certain acceptable range or area, there is less clean up to do later, we don't have to listen to complaints, and generally life is good.

It does sound the same when you deliberately edit what I said to distort the meaning. Seems to me that you deliberately do this. I appreciate you keeping me on my toes by taking everything I say and distorting the context. Have you thought of getting a job with CNN?

So how do you shoe a horse with a broken back pastern axis Eric?

Lol! I took out the filler and left the meat of the subject.

I'm finding less and less reason to set shoes back any further than the nondistorted foot would be.

I've noticed my shoes are sort of moving forward in the last year or so. It may be that all the horses now have perfect feet with no distortion after spending some time under my care. That's gota be it. Now I'll have to come up with a book, video series and seminar tour.

What about wedging for correct alignment (obviously with solar support) do you think that helps to balance out the GRF or puts too much pressure on the already damaged soft tissue?

What are the usual concerns of a broken back axis?

`The heels crush and you get palmer hoof pain

I know other farriers that seem to have better results with wedges than I do. I can't say that I've given up on them, but I have more confidence in other methods.

IMEs wedging is not a good idea when the root cause is horn integrity due to excess moisture. A broken back foot does not just collapse in the heels. The toe spreads and runs forward, the center of the foot collapses and prolapses. I prefer capturing the dorsal wall with a deep seated full web rocker toe on an egg bar or egg-heart bar with a leather pad and a hoof packing with a high Venice turpentine content - something to dry out the sole.

IMEs I get vertical depth in the foot much faster with a descant type of hoof packing under leather than using a plastic wedge or a plastic pour in pad or impression material that would trap moisture against the sole rather than absorb moisture from the horn and at the same time kill any anaerobic stuff that would otherwise feed on the horn. If I do use a wedge, it is leather and it goes on with a bar shoe so that the back of the pad does not flap up and down sucking dirt and water into the back of the foot under the pad. I've pretty much given up on using any kind of full pad on an open heel shoe as it seems to function like a bellows when the horse walks through muddy water.

Just Like a Man

I have had some success with wedges; but you have to know when to pull them off. I have used mostly aluminum wedges on mostly TB's and a few WP QH's with an extreme H/L with a 3*; but caution it very well needed. it can more damaged and the frog can prolapse under the weight.
I have had were a TB stallion a few years back had navicular surgery; and needed a K-B Nav Egg bar shoe on; then you must use the K-B open heeled shoe [a 3* wedge shoe] on the other foot to compensate the until the foot is healed. then remove the wedge shoe and barshoe as per instructions of the vet and put a 2* wedge on while some lite exercise ei. shedrowing the horse....then went the vet says it is ok after the surgical x-rays give the all clear; then regular wide web aluminums can go afterwards for lite work.
hope this was informative information........

The only person I've heard of having success wedging is Linda. Most likely she uses one of those secrets one of the old timers showed her.

Most things I've read on wedging go about like this. Wedge shoes crush the heels so we need to move to a bar wedge to spread the load over a larger surface area, oops that didn't help, we're gonna need a wedge and equipak to spread the load over a larger surface area, that didn't help, let's wedge, add equipak, set the shoe back as far as we can and extend the heels out past the bulps. Ahhh, there we go, the heels aren't crushing anymore but the horse moves like shit.

My own experience is about the same as the experiences I've read about.