Quarter Crack Why Pull A Quarter Crack Together?

The hoof is extremely thin at the proximal border due to the coronary groove, and without stability it is difficult to achieve healthy growth at the coronet on instabale cracks. . In my (extensive) experience, stabilizing the borders of the crack results in better hoof growth at the coronet compared to not stabilizing the crack. Pulling the crack together stabilizes the crack in ONE plane, which is better (in my experience) than none. Stabilizing the crack in many planes is better, and I try to achieve this through the use of fabrics of different types oriented in different directions, creating stability in many different directions.

How orthotropic of you.

Pat, I'm kind of shocked that you would suggest the different planes in which a crack should be stabilized without acknowledging all the other factors that could possibly go into helping a crack. That doesn't sound like something you would do and doesn't sound like research.

Whadyawant a book acknowledging all the other factors?

OK. Every hoof deforms differently under load, so the advantage/drawback of repairing the hoof in the non-weightbearing position will vary for every hoof. Results will vary (it depends, before Rick chimes in).
"Pulling the crack together" will vary depending on the technique. If the screws are mounted on the surface of the hoof and the screw sand wires are applied to this level, the inner surface of the hoofwall will be in tension (pulled apart). If the screws are applied to the center of the hoofwall, this force will be minimized. All compressive forces are not the same, and there are certainly more forces to be considered.

Sounds complicated.

Very complicated, that's why we (collective) disagree and I am avoiding absolutes in my answers.
Everything works some of the time, but nothing works all of the time with cracks.

[USER=13]Spot On Shoeing[/USER]

Is Pat's theory correct? If the stress is pushing from the inside out creating a crack. The more proximal the wider the crack will be. How does the math work out?

Eric,
When plating a bone in surgery the palte side is in compression but the opposite side is in tension. I think the same principle applies to the hoof wall. If you place the outer surface in compression (via screws and wires on the outer surface), the inner hoofwall is in tension. This is basic mechanics, although the significance of the values could be debated. Placing the screw in the center of the hoofwall relieves this discrepancy of force.

My method of stabilization is to debride a dog bone or barbell shape to the center of the hoofwall on either side of the crack. I then fill the crack with carbon fiber and an adhesive to form a composite. The dogbone shape will prevent the crack from moving together or apart. It will prevent the crack from moving up or down. Multiple dogbones will prevent the crack from moving in shear forces. This repair is in the center of the hoofwall, so the force is the same on the inside and outside of the hoofwall. I thin place a couple of layers of carbon fiber and levlar oriented in different directions to increase stability.

In my opinion, this creates stability in several different planes and allows the best healing. It is not perfect, but it makes the most sense and has worked in my hands on many horses.

I did not say this, I said every crack behaves differently. I said that compressing the outer hoofwall results in tension on the inner hoofwall.

No worries! When in doubt I call a Jim to figure things out. I highly suggest everyone have a Jim.

Jim is not a multitasker. He'll have to file this away and respond after somebody else has figured it out

So if I put a hose clamp on a hose that is covering a pipe, and I tighten the hose clamp, the clamp puts compression on the outer hose. It seems that you are suggesting that this results in tension on the inner hose where it is compressed against the pipe.

It's dead, Jim.

If you have a reasonably large and thick cross-section of PVC pipe. Take the cross-section and cut a .25" on a table saw.

If you close that gap with a hose clamp you will bring the outside dimension (OD) together before the inside dimension (ID). If you built the area up with superfast and were pulling the gap together from further out this tendency would be even more noticeable. If however you pulled the gap together from the inside, then the ID and OD would meet much more uniformly.

Ok, making sense now in regards to forces on the pipe (wall) itself. Thank you.

BTW, I don't have a table saw, but I do have a 2hp, 17" band saw that has a 12" re-saw height capacity. I prefer unbleached ox bone to dog bone for nuts and saddles. And my volume knob goes to 11.

I was thinking of the innermost circumference of the pipe(wall) being compressed against the lamina (which doesn't exist in PVC pipe without flowing fluid or gas and a Reynolds number, but I digress . . .). So my question of whether or not we should be pulling the gap closed or just locking the two sides together is more related to the lamina/wall interface than the wall/wall interface.

Obviously there would be some kind of local inflammation in the area of an open, unstable crack. So would closing the crack help or hurt that situation? If the lamina was in tension due to the wall pulling away from that area as it expands, then it makes mechanical sense to close the gap. But, if the lamina is inflamed, then are we dealing with any swelling? If so, do we want to put pressure on said swelling by closing the circumference of the inner wall? This is the crux of my speculation, and I have no personal empirical data to support a stance for or against either option.

Cutting pvc doesn't duplicate a crack. The pressure from a crack is internal.

That's why people will dremel a bit to see how deep a crack goes. It doesn't open like an elevator door.

Eric Russell

Define internal stress.

IOW, force is pushing out to create a crack. For instance with a rotational deviation where the medial heel is rolling under creating a quarter crack, ground pressure is pushing the heel in and then the pressure moves up and is pushing out near the hairline.

I can come up with all kinds of scenarios with forces going this way or that way but I can't think of any the would direct force in at the hairline for a quarter crack. I can't think of anything that would cause a quarter crack to open like an elevator door either.

I guess you could say a flare would direct force in further up the foot but I don't recall ever seeing a quarter crack appear because of a flare.