Continuing from my last blog, let’s look at when the orthopaedic loading is compromised. This challenges the relationship between the foot’s soft tissue architecture and the limb’s bony column.
Many issues cause the breakdown of internal hoof structures. Whether it be an incorrect hoof angle, medial-lateral hoof imbalance, upper body issues, orthopaedic imbalance, a change in the body’s centre of mass, or incorrect vascular infusion and neurological signals within the foot, the animal’s biomechanics interrelate in a way that, when challenged, sends the entire body on a downward spiral.
My years of research and practice support the premise that the digital cushion plays an important role in supporting the limb, maintaining hoof and limb alignment, and reducing excess movement and concessional forces. However, the digital cushion cannot achieve the task independently; it relies on being supported by a functional frog housed correctly within the hoof’s internal bars and is ‘held in’ its structural alignment by the collateral cartilages and a correct vascular infusion.
When searching for the onset of the downward spiral of the foot’s internal structures, we must turn to each structure's attributes and timeline of dysfunction according to its role in maintaining the integrity and functionality of its own and interrelated structures.
When looking at the internal hoof’s structural dysfunction timeline, we may find that the internal bars are the first components to exhibit issues; they modify their structural shape and alignment to reduce their height and length. The change in their shape compromises the foot's function; the internal bars lose their ability to correctly contain the digital cushion under the limb’s bony column, impairing its supportive role and disrupting its internal relationship with the limb’s distal bones.
The structural integrity of the internal bars relies on their shape and alignment within the hoof capsule. When viewed laterally, an internal bar is a triangular shape with its apex starting at the apex of the frog and ending with its base at the palmar section of the foot. The inner wall that frames the digital cushion begins straight and smooth and becomes slightly concave in shape at the distal palmar area collaterally. The outer wall is slightly concave throughout, thinner at the proximal border, and thicker and more developed at its distal border. This structural alignment houses the wings of the distal phalanx and contains the digital cushion correctly and directly under the main supporting bony structures of the limb and the distal interphalangeal joint.
The slight inner concavity of the internal bar collaterally is important. It allows for a small amount of digital cushion to form in this area; its significance is that it helps support the internal bar’s capability of absorbing the first impact with the ground and of allowing the efficient timing of hoof expansion during the downward rotation of the middle phalanx, as it copes with the loading forces while maintaining correct vascular infusion of the distal structures of the foot.
When they are compromised, the loading forces on the palmar section of the foot impair appropriate vascular flow to all the internal structures of the foot, including the internal bars and digital cushion, and, as a result, they all undergo extreme cellular and structural changes.
We will follow this look at the palmar foot loading in the next blog.
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