Farriers are often injected into the management protocol of club-footed horses with little to no history about the condition’s onset. Successful outcomes can be achieved through the understanding of basic anatomy and applying biomechanical principles to these cases. There are many factors, arguments and theories to describe the causes or reasons a horse may present with a club foot; these require their own article. This article seeks to describe the authors’ management of club feet in the aged horse regardless of how it was acquired.

Biomechanics can be defined as how internal and external forces interact with an animal’s musculoskeletal system, and how mechanical principles (such as leverage reduction) can be employed to gain mechanical advantage.

Understanding the basics of functional anatomy is key to utilizing biomechanics in managing club feet. The deep digital flexor tendon (DDFT) is the main culprit, and the terminology for the thoracic limb will be used for continuity. The subcarpal (inferior) check ligament also contributes to the condition and can be transected through surgery as a therapy for treatment; however, this will be omitted from this article. The following focuses on shoeing modalities for everyday management.

The DDFT originates from the deep flexor muscle and is unique in the fact that it originates from three muscle heads. It courses distad along the palmar aspect of the cannon bone, makes a bend around the navicular bone and attaches on the palmar solar aspect of the coffin bone at the semi-lunar crest. The main job of this tendon is to flex the coffin joint. Tendons, by design, are highly organized parallel bundles of collagen fibers that lack the ability to be elastic and are “cables” that pull based on the firing of muscles. To aid in excessive forces, the DDFT has an inferior check ligament that originates from the distal row of carpal bones and proximal cannon bone.

Why it Happens

The main cause of club feet stems from a shortening of the musculotendinous structure in relationship to bone length. Effectively, this means that based on the length of the DDFT in relationship to the bony column length, the origination point and insertion point are farther apart than the tendon is long. This misaligned correlation creates a broken forward hoof pastern axis (HPA), flexoral deformity of the distal interphalangeal joint (DIP) joint, excessive heel growth, abnormal concussive forces in the limb, heightened compressive forces in the dorsal capsule, and, when radiographed, the palmar angle of the coffin bone can be extremely positive, from 8-45 degrees, according to Dr. Ric Redden’s grading scale of club feet (Figures 1-5).

FIGURE 2 a,b,c: The hoof demonstrates growth ring disparity from toe to heels. Remington Leach

Blood circulation is also a consideration when addressing the club foot. Due to the conditions, the blood supply to the dorsal sole corium, dorsal venous plexus and dorsal aspect of the coronary plexus is compromised, resulting in slow dorsal wall growth. Conversely, the blood supply to the caudal aspect of the foot is widely uninhibited, allowing excessive heel growth.

FIGURE 3: A lateral-medial radiograph of Figure 2c. Note the proportions around the center of rotation of the coffin joint. Note the extreme palmar angle in relation to the plane of the distal capsule. Remington Leach

Trimming Club Feet

Considering the anatomy involved, a plan can be gathered based on addressing the imbalances of the biomechanical makeup of club feet. The shoeing modality goals should be to reduce tension on the DDFT, increase load in the foot’s caudal surface, ease concussion at landing, facilitate leverage reduction at breakover and reduce flexion of the DIP joint.

Trimming the heels to the highest and widest part of a properly trimmed frog is an adequate and accepted first step. In some cases, trimming to the frog-heel junction is desired to gain more heel surface to load, according to Dr. Sammy Pittman. However, if the treatment ends there, the target has been widely missed.

FIGURE 4: Dr. Ric Redden classifies club feet with four grades. Remington Leach

If left this way, even with a flat shoe applied with a rocker toe, for example, the amount of tension added to the DDFT is more than before. Effectively, the farrier has lowered the palmar angle of the coffin bone and this only means more trouble for the DDFT. Elevating the angle of the foot is commonly known to reduce tension of the DDFT, and by trimming the heels of a club-footed horse, the palmar angle is lower and now must be raised to take tension off the DDFT. This is evident by observing the heels not contacting the ground after the initial trim (Figures 5 & 6). It’s impractical to think that one can “wedge a horse with its own foot,” because tubules grow down and forward, which pushes the buttress forward under the capsule.

FIGURE 5: The heels do not touch the ground after the trim. Remington Leach

It’s important to note that lower grades of club feet may not need the “kitchen sink.” In a grade 1-2 case, the trim described previously may be sufficient in maintaining a healthy capsule and sound horse. With a higher grade, more mechanical advantage may be necessary. As with any case, careful attention should be paid to reading what the foot and horse are trying to communicate.

FIGURE 6: A rasp is slid under the heels of loaded foot after trim. Remington Leach

Shoeing the Club Foot

Once proper balance has been achieved, we may need to artificially replace what was removed in the trim. Adding a 3-degree wedge pad could be applied in this situation. This should be a sufficient addition to engage loading of the back half of the foot but may not always coincide with a change in the coffin bone’s palmar angle.

At this point, the center of pressure on the solar surface of the foot is redistributed to put more pressure toward the heels. Additionally, compression of the vascular structures in the toe/dorsal region has been relieved and compression of the plexus in the caudal capsule has been added. In some cases, the use of an additional wedge pad or wedged shoe may need to be utilized.

FIGURE 7: When a full shoe rocker is applied, it must match the rocker that was trimmed in the foot. Remington Leach

Half of the goal has been achieved, but now considering the horse in motion must be addressed. The remaining two aspects of the stance phase of the stride (midstance has been addressed above) are important to the DDFT.

Landing arguably causes the most instant and long-term damage to the limb with a club foot by excessive concussive forces through the podotrochlear apparatus, joints and bony column. The heel-first landing also causes the toe to “slap” the ground, thus aggravating the coffin joint. Additionally, the DDFT is under the most strain during breakover.

FIGURE 8: A full rocker shoe, also known as a banana shoe. Remington Leach

A full shoe rocker (commonly called a “banana” shoe) can help to alleviate both forces (Figures 7 & 8). The heel rocker portion, which can be applied to any shoe, is the most significant factor in proper application with positive results. This allows the caudal aspect of the foot to be closer to the ground during landing, resulting in a smoother “roll” to midstance while minimizing a toe slap.

FIGURE 9: A shoe with a full rocker and wedge pad is applied. Remington Leach

The rocker in the toe, which is smaller than the heel rocker, aids in a shorter lever arm at breakover, reducing stress on the DDFT at that point. It’s important to note that the heel rocker should begin no farther forward than the end of coffin bone wings. This will ensure that the foot cannot “rock” backward, with the goal being to have a flat area in the shoe that cradles the center of rotation (Figures 9-11). If the nail heads stick up higher than the ground surface of the shoe, they must be rasped flat so they don’t interfere with the mechanics of the shoe.

FIGURE 10: In severe cases, additional wedges may be necessary. This foot is shod with a Nanric rail shoe with a 3-degree wedge pad. Remington Leach

Through understanding basic anatomy and the biomechanical function of the DDFT, management of club-footed horses should become somewhat logical. The extreme cases have been omitted due to the potential for surgery involved and deserve their own attention. Reducing tension on the DDFT in static and dynamic movement, alleviating compressive forces on the dorsal blood supply, dissipating concussive forces and using mechanical advantage in the shoeing package can aid in creating a better “healing environment” for horses exhibiting club feet. 

FIGURE 11: This is the same foot from Figure 3 after shoeing. When de-rotating the coffin bone, the goal is to have the shoe plane match the palmar angle of the coffin bone. The balance is redistributed around the center of rotation. The dorsal green line identifies the breakover point of the rocker toe. The mechanics in the shoe package, as well as the trim, match the palmar angle of the coffin bone. The horse is shod with a SoundHorse Series 3 Sigafoos cuff applied to a Nanric rail shoe and a 3-degree wedge pad. Remington Leach