Coffin Joint

STEVE: The coffin joint is encased inside the hoof itself. It is a joint that exists between the third phalanx, or the coffin bone, and the short pastern bone.

Another integral part is that the flexor tendon, which runs along and attaches on the base of the coffin bone — and has the navicular bone attached across it as it runs underneath there — is part of this structure or, at least, incorporated into part of the structure, along with the navicular bursa. So all of these things are interrelated.

What we find with the coffin joint is, if it’s not a problem, it usually doesn’t get noticed much. But if it becomes a problem, it’s usually a big problem.

Coffin joint arthritis is a pretty complex problem that comes from performance, but it can occur in almost any type of performance horse, whether it be a race horse, a dressage horse a pleasure horse, a roping horse or you name it. And the problem is, when you get deterioration there or you get inflammation there or a lack or a loss of the cartilage in the coffin joint between the P3 or third phalanx and the second phalanx or problems in the navicular bursa area, these things all tend to interrelate, and they can create a pretty profound lameness. Because somewhere on the order of between 23 to 27 percent of the movement from the end of the cannon bone down to the ground is involved in the coffin joint. So you cannot lose any appreciable movement or flexion or movement in the coffin joint without affecting the overall gait of the horse.

INTERVIEWER: Are there things that can lead a horse to having coffin joint issues, like a bad angle of a foot or things like that that would maybe predispose a horse to coffin joint issues?

STEVE: Yes, definitely. Obviously, they have a predisposition, based on, if you got way too low of an angle, too long a toe — these things will cause the extensor process of P3 to come up into and bang on hyperextension into the pastern. So, therefore, you can create more and more irritation to the extensor process and/or the structure associated with it.

In addition, this also with low heel, long toe situation can also create problems with navicular bursa, which basically is interrelated with the coffin joint.

So maintaining a proper angle through your blacksmith is paramount. Maintaining length of toe — as far as backing it up properly — can help maintain that coffin joint and the silence associated with it. Making sure that you don’t chop their heels off and lowering that angle will essentially maintain the coffin joint confirmation and/or decrease the predisposition to coffin joint arthritis or inflammation or problems with it.

So a combination of balanced shoeing, symmetry and attention to proper measurement so that the toe and the wall and the angle, are all paramount to maintaining coffin joint soundness and/or the status of the coffin joint.

INTERVIEWER: So how would you diagnose a horse that has a coffin joint lameness?

STEVE: It’s actually quite interesting. I learned it when I was working on standard breds, primarily, but now I utilize it in all sorts of different horses: show horses, racehorses and standard breds.

What we find is that a lot of horses with coffin joint problems tend to show that they have a very shuffle-y gait; they don’t tend to extend the way you want. And people, I think, get the impression that the horse doesn’t want to extend. I think it’s more of a component that they don’t want to pull that leg back as far because, on more hyperextension with the limb back, the coffin joint arthritis creates more discomfort. So they tend to keep their limbs out in front of them and tend to shuffle a little bit short, so they don’t have as much differentiation in stride.

On physical examination, what I see in a high percentage of these cases is they have effusion to their fetlocks. But when you isolate fetlock fusion, or a fetlock flexion, you don’t get much reaction on the exam itself. But, when you incorporate coffin joint flexion with it, you see a pretty profound reaction.

A lot of times what I will do, is I will watch a horse trot, then I’ll come back and put him in a flex situation and trot him off, and we’ll see that we exaggerate a lameness problem or a deficit in that limb. And then we’ll do it on the other side, and we’ll see the same sort of thing. So it tends to be bilateral — with one tend to being more prominent than the other — which is not unusual in any lameness case.

INTERVIEWER: Pardon me for interrupting you, but coffin joint flexion and fetlock flexion are really two completely different things.

STEVE: Well, they can be, but unfortunately, when you add in the coffin joint, you like to grab the pastern and flexor coffin and isolate it from the fetlock. So it takes a little bit more experience, knowledge and a lot more detail when you do this — but you need to isolate both in order to get the most out of your examination and determine where the source is coming from.

INTERVIEWER: Can you X-ray a coffin joint and diagnose that way as well?

STEVE: Definitely. I don’t use the X-ray for the diagnosis, but I’ll certainly use it for the confirmation for deficit or problem in that area, for sure.

INTERVIEWER: And here’s the ultimate question. How do you treat it?

STEVE: Well, it depends on the severity. Sometimes something as simple as shoeing can remedy the problem. Sometimes you have to be more aggressive. Sometimes you have to go with an anti-inflammatory. Sometimes you have to go with topical therapy. Sometimes, you have to go with intra-articular injection. Sometimes, you need to go with a combination of all of the above. Shooting, topical medication and injection. In order to maximize the horse. Sometimes we see very profound changes by a combination of these things. Sometimes we can just do one thing and we can basically make the horse go 100%. So it depends on the severity, the diagnostics, the treatment and response to the therapy. And all these things will give you a better feel for how your horse is going to do, and if you can maintain it or not.

INTERVIEWER: How important is the synovial fluid around a coffin joint?

STEVE: It’s very important to maintain the quality of this fluid. This fluid is the lifeline of the synovium to that cartilage to maintain those structures to help get the most amount of lubrication or decrease the inflammation, and to get the maximum amount of better quality fluid in the joint. When you get that, you get a good clinical response. The best clinical response when you get that earlier, the better, more preventive — versus trying to do it after the fact.

INTERVIEWER: Is there a correlation or relation between coffin joint soreness and navicular?

STEVE: Yes, most definitely.

They’re very, very intimately related. As we can see here, anatomically the coffin bone is right here. Here’s the pastern that we’re talking about. Here, this small bone right here, (number four) is the navicular bone itself.

This is the coffin joint. As you can see, the coffin joint also exists down in here where it’s intimately attached to the navicular, and the navicular bursa is a small sac that basically occurs right in behind here, underneath the deep flexor tendon.

So, when you have a problem with one, you tend to have interrelated problems with the other as well. And we will utilize injection of the coffin joint to help improve navicular bursa inflammation or decrease it and/or problems in the coffin joint.

INTERVIEWER: Now in this type of injury, is there a way to feel for heat in a horse’s hoof? Is that directly related to these issues?

STEVE: Yes it is. Actually, the pulse and the heat in the foot — what I do is when I’m doing a physical examination, I can feel pressure right here on the outside of the coffin joint, when there’s effusion or an excessive amount of fluid there.

In addition, sometimes when there’s too much fluid in the navicular bursa that will back up into the digital sheath, you can feel fluid right back in here in this ball between the ball of the heel or back in the digital sheath. And when we flex it, we get a pretty profound reaction or withdrawal response — they try to pull one away when we flex the coffin.

Navicular disease is an area where you have deterioration primarily in this bone in the coffin or inside the foot. Typically a horse that has navicular disease or heel syndrome or heel soreness, which is chronic, usually is a foot that is very small for the mount or the size of the horse. They tend to be contracted or closed in. They tend to be basically too small-footed, essentially for the size or mass of the horse.

What we see in this area on ReadiGrass, soreness, we see with hoof testers, soreness across the base of the frog and/or the base of the heel where the navicular bone resides up in here. And we see a very typical, short and sometimes obviously, a lame gait, at trot for both directions, with it being worse on the inside of a circle. And so what we do is try to remedy this, we will address therapy to protect this area from concussion, improve the area of circulation and try to make break over easier where we’ll go ahead and roll the toe and allow this horse to break over easier, so we take less pressure on the heel. That’s what our therapy is directed toward.

We can also inject the coffin bone or coffin joint to get circulation or improve fluid to the navicular bursa and the structure supporting the navicular. And in addition, systemic medications, anti-inflammatories and sometimes anticoagulant therapy can help circulation in this area as well.

INTERVIEWER: In my travels, out and about for promoting LubriSyn, I’ve talked to a lot of people that have issues with navicular. So it seems to be an issue with older horses, primarily?

STEVE: More commonly older. We see early problems with heel syndrome, but the true navicular disease, I haven’t personally seen in a horse any younger than five. That’s been my impression over the years.

INTERVIEWER: It is treatable? It is something that horses can live with?

STEVE: Early on. Typically, the same situation as usual — preventive medicine being better than restorative. The quicker that you can address this area, maintain their break-over, maintain health of coffin joint, the navicular bursa, protect the area of the frog and/or allow for expansion — all the normal things — the better you’re going to be off early, and you’re going to maintain their soundness much longer and have a lot more productive career.

INTERVIEWER: And how about diagnosing navicular? What’s some of the symptoms a horse would show?

STEVE: Well, obviously lameness, for one. In one limb versus the other, more of the inside limb versus the outside on circle. They’re going to have confirmation, small foot, big, heavy-bodied horse. Typically, more quarter horses than others. And another thing we see that is pretty typical is they can have increased pulse, and we usually can block them out with just a post-digital nerve block and we see drastic improvement right away.