ARCHIVE - ARTICLES 2010

December 10 - Shoeing Around the Coffin Joint

 

Archive - Forge Magazine - December 2010
Shoeing around the coffin joint

Jim Ferrie

The coffin joint is the most distal joint in the horse’s muscular/skeletal makeup; consequently this joint comes under tremendous stress from the forces above and as a result is often a source of lameness.
Anatomy of the coffin joint
The coffin or distal interphalangeal joint is the intersection of the coffin bone with the short pastern bone and the distal sessamoid or navicular bone.
The joint is a hinge joint and also a saddle joint due to the unique shape of the coffin bone. The coffin bone and short pastern bone are joined medially and laterally by a group of ligaments known as collateral ligaments. The navicular bone is attached to the coffin bone distally by the impar ligament.
Two collateral ligaments also hold it in suspension. The deep flexor tendon uses the navicular bone as a fulcrum before its insertion on the solar surface of the coffin bone.
The junction between bones is called the joint capsule and from here the synovial fluid, which lubricates the joint, is secreted. The joint also plays a part in shock absorption during locomotion.

Captions from top to bottom:

Looking downwards on the coffin and navicular bones showing the collateral ligaments of the navicular bone

The extensor process, showing the articular cartilage

Lateral view of the ligaments below the fetlock

The coffin bone and the collateral cartilages

Anterior/posterior (dorso/palmar) balance
Viewed from the side, a line dropped from the centre of the coffin joint should divide the ground surface of the hoof into two equal halves.
The x-ray below shows the amount required to be trimmed in this unshod hoof to achieve a balanced coffin joint.
Note
The toe must be angled at 45° to the ground to facilitate this balance, if the wall were to be thinned from the coronet to the point of breakover, then the laminar attachment to the coffin bone would be compromised rendering the horse lame.

Locating the centre of the coffin joint without an X-ray
The centre of the navicular bone (yellow dot) is located in the middle of a line drawn between the coronary band at the front and the furthermost part of the coronary band at the bulbs of the heels.
If the portion in front of the midline is divided into thirds exactly one third in front of the centre of the navicular bone is the centre of the coffin joint (blue line).
If this line is carried on to the solar surface of the hoof it gives the farrier a datum point around which the hoof should be trimmed or shod.
Each hoof is different, as the length of the frog is governed by the height of the heels.
Trimming around the centre of the coffin joint
The black line shows the centre of the coffin joint.
On this hoof the wall to the toe does not conform to what is perceived to be ‘normal’ and must be brought back even farther to achieve balance.
The reason for this type of hoof capsule is due to the conformation of the front limb. The knee is in a backwards position from vertical making a normal hoof pastern axis impossible.

The overhanging toe is blunted to achieve balance around the centre of the coffin joint; the green line shows where a conventional shoe might be placed.
Personally, I like to shoe in three dimensions around the centre of the coffin joint. I believe that this is the centre of articulation and the whole horse pivots around this point on all four legs.
Consequently, I use shoes with the ground surface rounded to minimise the stresses during locomotion.

Roller Shoes with the ground surface nicely rounded
Other methods of achieving dorso/palmar balance
Graduating the heels
This can be done with either a graduated shoe or a graduated pad between the shoe and the hoof. The shoe can be open heeled or a bar shoe .The disadvantage to this type of shoe is that the frog does not function properly and consequently the heels are lowered even more as the frog descends downward with each stride.
Some sort of frog support should be used with the graduation (see pictures).

Plastic wedge with frog support
Graduated bar shoe
This should have hoof packing on the solar surface to enable the frog to function

Mediolateral balance around the coffin joint
It must be remembered that we are not shoeing a table leg. The horse is a dynamic animal and we must observe it as such prior to shoeing or trimming.
Over a number of years and evaluating thousands of horses before shoeing, I have found that the accepted method of trimming (to the long axis of the forelimb) does not apply in a large number of horses.
Conformational problems involving the knee and canon bone and the cannon bone and the long pastern, don’t just lead to angular limb deformities, but also to rotational problems, where the articular surfaces of the above joints rotate (turn) outwards or, much less commonly, inwards.
This type of conformation will usually not normally present as a problem until maturity, when the elasticity of the joints cannot accommodate uneven ground contact, and the resulting loading on just one side of the hoof and limb causes lameness. This lameness initially shows as sore to turn in a tight circle and gradually worsens if the limb /hoof imbalance is not addressed.
I have a very simple solution to addressing the conformational problem, and that is to trim or shoe to achieve level footfall on a firm surface.
In the forelimb, a very slight lateral (outside) first ground contact is perceived to be normal.
During forward motion, animals with an outward rotation between the knee (carpus) and the cannon bone will usually toe out, break over to the inside and place the hoof outside the middle of the leg to land flat. This causes excess load on the inside of the leg and hoof. To address this problem, especially in a young horse in which the growth plates have not yet closed, I trim the hoof on a spiral, which would see the outside lowered to allow normal footfall.
Often when the mature horse is lame with an outward rotation of a joint enough cannot be safely trimmed and level footfall must be achieved by making the spiral with a shoe.
Soundness is seldom achieved instantly, since so many structures in the leg have to be de-stressed, but over three or four shoeings in this manner normality should resume.
Much less common is an inward rotation of the joint, when trimming on a lateral spiral is beneficial.

Note
Sometimes unlevel footfall can be due to acute trauma to the hoof causing abnormality in the stride; this must be eliminated before adopting spiral treatment

Fabricated Medial Wedge; Before Trim; Spiral Trim

Medial wedge bar shoe (forged from a graduated bar shoe)

All anatomy slides courtesy of Mitch Taylor Kentucky Horse Shoeing School
Contact Jim Ferrie by email [email protected]
This article appears on www.j-aferrie.com and is reprinted with permission of the author

 

Archive - Forge Magazine - December 2010
Richard Ellis Fundraiser Clinic

Charles Mann

The Handmade Shoes clinics have become popular events over the years, but the one on 16 October was a little different to the others.

This was essentially a fund raising event for former world champion farrier Richard Ellis FWCF who is suffering from myeloma, a rare and particularly debilitating bone marrow cancer.
Friend and colleague Billy Crothers AWCF began a campaign to raise money for Richard and his family through his ‘Shoe a Horse for Richard’ initiative and then came up with the idea for the clinic.
Normally free to attend, Billy asked visitors contribute to Richard’s fund. As well as this, there was an auction that helped raise the final figure to nearly £18,000.
The event followed a familiar format at the Handmade Shoes premises in Pitstone in Buckinghamshire. There were three demonstrations featuring David Gulley FWCF, Jim Blurton AWCF and Dave Richards followed by a farriers question time and, of course, the auction.
David Gulley, that master of master farriers, shared his experience and knowledge of training apprentices in the art of shoemaking. With his unique, dry style in a short space of time he was able to convey an extraordinary insight into the common mistakes that apprentices make. He shared ways in which a training farrier can anticipate them and improve the learning experience for the apprentice whilst at the same time helping them be an asset to the business rather than a burden.
His essential point was that apprentices should be taught how work a system and keep with it; be efficient but not boring.
The essence of this, he explained, was to retain the simplicity of making shoes – in other words, to teach a little at a time and to allow the apprentice to become proficient before moving on. His experience was that teaching too much in one go meant less was absorbed.
His demonstration of such essentials as handling of the tongs and the position of the shoe on the anvil aptly demonstrated his point.
Jim Blurton ran a session on the application of graduated bar shoes.
When to use them was really the first question and to answer this he suggested that a number of symptoms may point to the use of bar shoes. These might be low grade lameness or apparent laziness with the horse not stepping out properly. He did, however, caution ‘over diagnosis’. Lameness may be a reaction to pain elsewhere; it isn’t always due to uneven footfall.
So the point of using bar shoes was to stabilise the hoof structure and to create the conditions for the reinstatement of the integrity of the foot, Jim said.
He took his audience through a demonstration of foot preparation including a real-world discussion on what foot symmetry actually meant and then showed how to set the sole plate to achieve an appropriate amount of sole pressure.
On the anvil the demonstration moved to the shoe design itself including the significance of its balance point. The slightly counterintuitive method of adjusting the shoe for fit also featured.
The third demonstration was from Dave Richards of Equicast who showed how to use the Equicast EVA (Ethylene Vinyl Acetate) System in the case of a multi-dimensional failure of the hoof wall.
He explained how blood flow goes to the areas of stimulation. In a hoof this is that which is in contact with the ground and hence how the hoof grows. By using a circumference cast the aim is to keep the medial and lateral walls balanced. Adding support slows down cranial growth of the heels from over stimulation.
After some discussion around whether to shoe or cast first, Dave went on to demonstrate the use of EVA and wooden shoes. These provide support by encouraging growth of the hoof wall whilst avoiding sole pressure.
A number of conditions were discussed regarding application of the system such as prolapsed frog, club feet and coffin bone fracture. The importance of the trim was also emphasised; the cast will merely preserve the trim so the horse will still become sore if overdone.
In his concluding remarks, Dave urged farriers to be much more assertive in the intervention and treatment of chronic founder in order, he said, to create sole depth.
The afternoon finished up with a question time featuring Billy Crothers, David Gulley, Tim Rooney RSS, Jim Blurton, Carl Bettison AWCF and Gary Darlow AFCL on the ‘panel’. In a session that lasted well over an hour, the panel reflected in the influence Richard Ellis has had on them personally and professionally and shared their own thoughts on a broad range of topics including preparation for competition, the role of ATFs and colleges, the relationship between farrier and horseowner and concerns about the effect of VAT on pricing.