Q: Is there a way to tell the difference between a clubfoot situation that can be "fixed" and ithe one that only can be managed?
A: It’s difficult to “fix” a clubfoot, even with surgery, but they can be managed quite effectively depending on the severity.
A true clubfoot conformation has a genetic component and is associated with a flexural deformity (flexion) of the distal interphalangeal joint (coffin joint). It’s characterized by a broken forward hoof-pastern axis, which is a reflection of a hoof capsule where the angle of the dorsal hoof wall is greater than the angle of the dorsal pastern.
This broken forward hoof-pastern axis or flexural deformity is created by some degree of shortening of the musculotendonous unit (deep digital flexor tendon [DDFT] and associated muscle bellies) causing the distal interphalangeal joint (DIP) to be drawn into a flexed position. The shortening of the musculotendonous unit causes a disparity of hoof wall growth with more growth being produced at the heel than at the toe. The excess hoof wall growth at the heel is to compensate for the shortened musculotendon unit.The frog generally recedes due to excess hoof wall growth at the heels, such that the energy of impact is assumed by the hoof wall, bypassing the soft tissue structures and transferring the load directly onto the bones of the digit through the laminar interface. The excess growth at the heels places the distal phalanx (P3 or coffin bone) in an abnormal position within the hoof capsule, such that more weight bearing is assumed by the dorsal section of the foot. The anatomical features of a clubfoot can be readily seen on a lateral radiograph (Figure 1).
A clubfoot needs to be differentiated from an upright foot or a foot with a steep hoof angle. High hoof angles without phalangeal misalignment or with mild phalangeal misalignment can generally be improved by gradually lowering the heels in a tapered fashion from the apex of the frog to the heels. This increases the ground surface of the foot and attempts to re-establish weight bearing on the entire solar surface of the foot. Breakover is moved palmarly at the same time to compensate for any increased tension in the DDFT created by lowering the heels.
Farriery for a high hoof angle with concurrent phalangeal misalignment (clubfoot) becomes more of a challenge. Flexural deformities are usually diagnosed and treated while the horse is immature. The object of farriery is to load the heels, compensate for the shortening of the deep flexor tendon, improve the hoof-pastern axis when possible and realign the distal phalanx within the hoof capsule. To accomplish these objectives, farriery is directed at lowering the heels, but the amount to remove can be hard to determine. In mild to moderate clubfeet, an estimate of how much heel to remove can be made by placing the thick end of a 2- or 3-degree pad under the toe of the foot and allowing the horse to stand on it. If the horse doesn’t resent the tension it places on the deep flexor tendon, the thickness of the degree pad can be removed in a tapered fashion, again starting at the widest part of the foot.
The toe is shortened by backing up the dorsal hoof wall with a rasp. The trimmed foot is fitted with a shoe that has the breakover forged or ground into it, starting just dorsal to the apex of the frog and tapering toward the toe to further decrease the stresses on the DDFT.
With the more advanced cases of clubfeet, the hoof wall at the heels should still be lowered to load the heels and unload the toe, but heel elevation will need to be added to compensate for the shortening of the musculotendon unit. This can be demonstrated, following the trim, by placing the trimmed foot palmar to the opposing limb. If there is a space between the heels of the foot and the ground, a wedge shoe is used or a degree pad or a bar wedge is placed between the heels of the foot and the shoe to compensate for the shortening of the tendon unit. This method allows the heels to be fully loaded, but at the same time will decrease the stresses in the musculotendon unit. Breakover must be addressed and is applied as described above.
The treatment of severe clubfoot (flexural deformity) can be handled at any age by employing an inferior check ligament desmotomy combined with the appropriate farriery.
— Stephen E. O’Grady, DVM, MRCVS, Marshall, Va.