What the Hell is a Phalangeal Lever & Why Should I Care?

© Tom Stovall, CJF

Consider the front feet of the horse. Now imagine a line which travels along the midline of the dorsal portion of the horse's lower leg and hoof, from the distal portion of the fetlock to the breakpoint - not the distal, dorsal portion - of the hoof. This imaginary line is the phalangeal lever.

Those bones distal to the fetlock comprise the longest portion of the phalangeal lever. These bones called "phalanges" and are, proximal to distal, the long pastern, short pastern and coffin bone. Most often, they are referred to as "P1", "P2" and "P3". The hoof capsule encases P3 and is a part of the phalangeal lever, but it is not necessarily a beneficial part of that lever; in fact, the hoof capsule, under a great many circumstances, can act in opposition to the efficient function of the phalangeal lever.

What was that about efficiency?

Any horse, at any natural gait, operates most efficiently when the phalangeal lever is as short as practicable without impairing the hoof's ability to deal with environmental hazards.

Simply put, this means that the shorter the better, unless the protective functions of the structures on the ground surface of the foot are impaired. A short foot is efficient, but efficiency suffers somewhat when one can feel Dobbin's pulse through the sole.

Please note the term "natural". There are several gaits that can be enhanced by making the horse less efficient (for example, the addition of weight and/or length to a pacey Walker to enhance the running walk), but those gaits deal with arbitrary, subjective standards, not efficiency. Efficiency deals with getting Dobbin from point "A" to point "B", at whatever gait, with the minimum expenditure of energy and the fatigue intrinsic thereto.

Length of the phalangeal lever is only one factor influencing efficiency, angulation of the lever must also be considered. Just as length has a direct bearing on efficiency, phalangeal angulation is also directly related to the amount of work Dobbin must do in order to turn his foot over. Generally speaking, most light horses operate most efficiently with phalangeal angulation of between 50 and 60 degrees on fronts, 45 to 55 degrees on hinds, measured radiographically.

To digress for a moment, a hoof protractor is virtually useless in the determination of phalangeal angulation in many horses because, although the hoof capsule encases P3, the capsule does not always reflect the true angulation of that bone. A hump or dish in the hoof capsule, unnoticed rotation of P3, or an overzealous farrier's rasp can render an inaccurate reading on any protractor because that device is dependent on a relatively straight dorsal wall for its accuracy. Only a lateral radiograph allows the accurate measurement of phalangeal angulation because the hoof wall is not relevant to that measurement.

A third factor influencing the phalangeal lever is alignment. The phalangeal lever operates most efficiently when, viewed laterally, the phalanges are aligned in a relatively straight line. Phalangeal alignment has to do with the transference of energy from the horse's muscles to the ground, support of the horse's weight and the dissipation of concussion. All of these factors are most efficiently addressed by the horse when the phalangeal lever is in proper alignment.

Okay, so the main factors influencing the phalangeal lever are length, angulation and alignment: So what?

Most of us have been taught that a farrier is supposed to shoe the hoof and that the hoof determines the shape and placement of the shoe. Everyone from Lungwitz to Butler has had something to say about fitting the shoe to the foot, not the foot to the shoe - and every blessed one of those authorities, even our sainted fathers and grandfathers, was wrong!

What heresy is this?

Think about it: if the object of the exercise is to shoe Dobbin so that he can do whatever it is that he does most efficiently, then we have to shoe the bony column, not the hoof. Shoeing the bony column begins with the phalangeal lever because, as farriers, we have a direct and immediate influence on that structure. We can't do much about the carpus and the scapula is bit out of our sphere of influence, but we can do something - good or bad - with the phalangeal lever. But first, we must think of the hoof capsule as a structure with which to influence the bony column, not as the most important structure to consider when shoeing the beast.

In making Dobbin be all he can be, we must sometimes disregard any preconceived notions we may have relative to the aesthetics of the hoof capsule.

The most common manifestation of shoeing the lever is the setting under of the shoe. "Setting under" means that the shoe, from about toe nail to toe nail, does not extend to the dorsal perimeter of the hoof capsule; rather, the shoe is fitted posterior to the perimeter and the overhanging wall cut off perpendicular to the ground surface of the shoe. Under most circumstances, the white line is the limiting factor in setting the shoe under; however, if necessary, methods exist for overcoming this limitation.

How does setting a shoe under affect the phalangeal lever? Think of what the foot looks like in a lateral radiograph. In a great many horses, moving the shoe posteriorly effectively shortens the phalangeal lever, increases angulation and usually brings the phalanges into better alignment.

How does this help Dobbin? Well, within normal parameters, the less work Dobbin must do to turn his foot over, the more efficiently he operates. (The "four-point" and "natural" trim proponents have jumped all over this premise and attempted to make a case for whacking out the quarters and the middle of the toe and allowing sole pressure because many feral horses in abrasive environments wear their feet in that manner, but their premise presumes their conclusion - which is a no-no in both physics and logic.)

Due to the advocacy of the holistic farriery inherent to the so-called "natural trim" by some veterinarians and farriers, one might get the impression that touchy-feely and being politically correct has become more important than the physics of farriery. Allow me to point out that feral horses neither carry weight in excess of their own, nor do they engage in forced exercise. For these and other reasons, data gleaned for feral horses cannot be extrapolated directly to domestic horses, other than in the most general of terms. It can be easily demonstrated that any short lever, with a fulcrum at one end and work applied to the other, is more efficient than a long lever of the same class, because it takes less work to move it. The data do not support any other conclusions, although subjective interpretations abound.

Nearly 20 years ago, Jack Miller and I were in Tucson, working a series of hunter/jumper shows. There, we found an inordinate number of hunters coming across our mats with the most godawful looking feet this side of a two-week shoeing school: they were short, flat across the toe and some of them had enough shoe hanging out the heel to be a Saddlebred - incidentally, the tack stalls of their respective trainers were decorated with an uncommon amount of blue ribbons. We asked around and found out who had been shoeing them and found it to be a San Diego farrier, Gunnar Gatski.

Gunnar began setting horses under because he found that doing so made most of his hunters move more efficiently. I have no idea what prompted him to begin doing so; but, since he is a fairly intelligent and resourceful individual, I assume he decided that "Daddydiditthataway" wasn't serving him too well and came to the startling conclusion that horses are not immune to the laws of physics.

Without really knowing the why of it, only the results, we shamelessly ripped off Gunnar's ideas and started shoeing everything with a low angle or a runout hoof capsule just like Gunnar had shod his hunters. It worked just as well for us as it had for him.

With one slight, but extremely important, modification. We found that the wall overhanging a shoe must be cut off perpendicular to the ground surface of the foot when the shoe is set under, and under no circumstances should it be "feathered" from the coronary band to the ground along its dorsal surface in an effort to make the foot look "pretty". Gunner did a great deal of rasping when he first evolved the method, but he found to his dismay that his making the hoof aesthetically pleasing destroyed the structural integrity of the hoof capsule. This lesson was learned when some very good hunters had to be turned out while they grew new feet.

Actually, the concept of enhanced efficiency through shortened phalangeal levers predates Gatski, although, to my knowledge, he was the first farrier to apply the idea to pragmatic farriery. As early as 1962, Dr. O. R. Adams advocated the disuse of toe grabs on runners in the first edition of Lameness in Horses.

What does a toe grab do?

As nearly as I can tell, the main function of a toe grab is to drum up business for track veterinarians by increasing the effective length of the phalangeal lever. In addition to the use of grabs, a bit of stable stupidity still persists at the race track which dictates that cutting down a runner's heels will somehow increase the runner's length of stride. If that bit of nonsense were true, if you barely outrun me in the trials of a futurity, I can whack off my colt's heels and have a mortal lock on outrunning yours in the finals.

Runners are an excellent example to consider when considering the effects of length, angulation and alignment of the phalangeal lever on efficiency because that efficiency can be translated, within each individual's physical limitations, to both speed and soundness. As most folks know, flat racers are notoriously unsound and the blame for this is not entirely due to age or workload of the affected horses. Trainer mentality (or lack thereof) and conventional track farriery can share in the dubious credit for this phenomenon.

Many of us are familiar with bucked shins, or periostitis of the dorsal surface of the third metacarpal bone. Most authorities attribute the phenomenon to too much, too soon: too much work by too young a horse; but, the increased length of the phalangeal lever caused by grabs is probably the most important factor. Not surprisingly, most runners buck shins when they are introduced to grabs.

How many of us have had a baby train sound on the farm, then buck shins as soon as he went to the track? Of course, the colt was training in half rounds or training plates at the farm, and the first thing the trainer did when the colt came into his barn was to have the nearest plater nail on a nice, shiny set of aluminum race plates, complete with toe grabs. After all, Everybody Knows, (also known as "Daddydiditthataway") a race horse has to have race plates. But, what do those grabs do to the phalangeal lever?

We didn't think about it much at the time, but every spring the track vets could get caught up on their bills about March or April on the proceeds of chip fracture surgeries. Strangely enough, although this phenomenon usually occurred concurrently with the use of toe grabs, most of us thought it was due to overwork, poor training, unsound bloodlines, or bad karma; we never suspected it could have been related to something as simple as our increasing the length of the phalangeal lever with toe grabs about the same time the runner was first asked to run as fast as he could.

Consider the bowed deep digital flexor tendon, a not uncommon malady amongst flat racers. Racetrackers usually think of bows as being a fatigue injury: they are relatively uncommon in sprinting Thoroughbreds, as common as white on rice on two-turn horses. Yet, Quarter Horses, which never run more than half a mile at the races, a distance considered a short sprint by the Thoroughbred folks, often bow their tendons. Coincidentally, Quarter Horses are commonly tracked only every other day and are routinely shod with a toe grab that is much larger than those normally used on Thoroughbreds. Could there be some relationship between bowed tendons and phalangeal levers?

How many times have we been allowed to keep a half round or a training plate on a bowed runner while he convalesced, had the horse stay sound when he resumed training, then had the horse break down again after the trainer insisted on grabs before running the horse? Phalangeal influence? Surely not.

It may be difficult to believe, but bows are not uncommon in Arab show barns. How in the world does a horse that only works on the flat and then only within the friendly confines of a manicured show ring ever manage to bow a tendon? Evidently, some trainers are unaware that a four and one-half inch foot and a 14-ounce shoe may be a bit much for an 800 pound Sheik of the Desert packing twenty percent of its body weight in rider and tack. Physics can be a harsh teacher.

You may be saying to yourself, "I shoe pleasure horses and pasture horses, this phalangeal stuff is for performance horses." And, to a degree, you would be correct in that assumption. The less a horse works, the less important the phalangeal levers.

If your clientele consists purely of pasture ornaments, you probably don't need to worry about such a boring, mundane subject as the care and feeding of the phalangeal lever. But, if your horses work for a living, understanding the phalangeal lever is of utmost importance because that knowledge is as important to the well being of your hoses as your knowing which way to turn a horseshoe nail.

Many of us are blissfully unaware that the main function of the horse's front end is keeping Dobbin's chin out of the dirt. The only function of the front end is support when the horse is at rest, or after forward motion has been established: the front end is propulsive only at the onset of forward motion or in lateral motion. With that concept firmly in mind, when one attempts to shoe the horse for efficiency at any gait, the most important factor becomes the removal of all impediments affecting turnover of the phalangeal levers.

How does one enhance turnover?

One enhances turnover by the mechanical manipulation of the phalangeal levers. Most often, simply by trimming or shoeing the horse on a timely basis. By keeping the toe as short as practicable. By radiusing the toe on trims. By setting the shoe under when the need exists. By using rocker toes, roller toes, half rounds and even rockered shoes. By doing whatever it takes to give the horse what it needs.

Given trainer mentality, you'll only be able to practice enhancing turnover on cripples or horses whose performance is objectively measured. Make somebody's horse sound or knock off a few hundredths off a barrel racer's time and they'll sing your praises to high heaven - at least until somebody points out that the horse's feet look like hell.

The length, angulation and alignment of the phalangeal lever is not writ on tablets of clay; to a surprisingly great degree, they can be manipulated to suit a particular set of circumstances. When one discards the notion that feet are "supposed" to look alike and approaches farriery with the objective of balancing the phalangeal levers for the horse's benefit, one can end up with some strange looking feet attached to some beautifully moving, sound, horses.

Consider the "one up, one down" syndrome, which is extremely common in some breeds of light horses: one foot is "normal"; the other is boxy, narrow and almost clubbed. When this horse walks up on your mats, you think to yourself, "Lungwitz couldn't shoe this rascal to move decent if Dollar was holding the shank and Adams was giving instructions."

But, you can. All it takes is a change in priorities: we need to stop worrying about the hoof capsule and to start worrying about balancing the phalangeal levers. With the idea in mind of balancing the phalangeal levers, the classic "one up, one down" conformation and the often attendant gait aberration of too much knee on one side and too much extension on the other can be remedied by simply shoeing one foot full, the other set under.

Oops, did I say "balance"?

Yes, I did.

The term "balance" has an esoteric, near mystical connotation because it's extremely difficult to determine when, or even if, it really exists. Farriers approach balance with almost religious fervor: Is the hoof capsule thus and so? Does the coronary band meet such and such parameters? Is the moon aligned with Mars?

Fortunately, phalangeal balance is not dependent on dogma: one merely attempts to cause the two levers to have the same length and angulation, the trick is that the hoof capsule is not considered in the equation, other than as a limiting factor.

Unlike many other manifestations of that elusive concept known as "balance", the existence of balance in the phalangeal levers can be determined by radiographic examination.

Please understand that all things being equal, horses with short, normally angled, normally aligned, phalangeal levers are more efficient and stay sound longer than horses that do not have those attributes. Therefore, it is incumbent on the farrier to do whatever is necessary to achieve this goal.

Tom Stovall is an American Farriers Association Certified Journeyman Farrier since 1983, a Member of the Texas Professional Farriers Association, and a Member of the Artists-Blacksmiths Association of North America. Thanks to him for his permission to post this article.

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