How to Evaluate Foot Flight and Leg Alignment

1. Introduction

A disciplined, methodical approach to assessing foot flight and leg alignment can sharpen the eye for details, clearly define each area of concern, and offer a means of classifying specific deformities relative to severity.^1,2  This ultimately offers more useful information required for an accurate diagnosis and efficient treatment recommendations. This approach is beneficial for assessing horses of any age, from diagnosing limb deformities in foals to identifying potential high risk factors in pre-purchase exams of adult individuals.

The notion of striving for “textbook conformation” has changed over the years because few if any horses exist that fit this age old model, and many of the cosmetic, uncategorized deformities once thought of as flaws are routinely found on superior athletes of most all breeds and disciplines.^3,4  Therefore this methodical protocol allows us to better understand variations in distance and structural angles that fall within the range of normal as well alterations that are not compatible with soundness.

2. Materials and Methods

Evaluating conformational correctness as well as undesirable defects and flaws is relative to knowledge of the subject, experience, and level of focus at the time of each exam. Using a systematic methodical approach for every exam offers a useful means of enhancing our ability to record small details that may otherwise be overlooked.

Visualizing planes of reference as imaginary dots, lines, and angles relative to plumb enhances our ability to make comparative, repeatable exams, thereby increasing our powers of observation (Fig. 1). Start by watching the individual walk straight away from you, preferably on a smooth surface. When observing foals, having someone walk the mare along a wall or fence offers a reasonable means of assessing the foal as he travels beside the mare. Focus on foot flight and the landing phase. Watch the hind feet land several times before focusing on the front feet as the individual moves away from you. Foot placement and full load stance appears to occur faster than the eye can detect, but with practice, closely observing the air space under the foot as it lands and loads acts to slow the action and bring out subtle details that might otherwise be overlooked.

Next, observe the foot flight and landing pattern of the front feet as the individual comes back toward you. Watch the lateral wall of each front foot land, then observe the medial wall. Note any differences between the two feet. Turn the individual and watch him walk away from you once again. This time observe the hind limbs, one at a time, from the hip to the ground as the limb flexes and extends to full length. Placing an imaginary dot at each major joint creates a reliable means of evaluating the angulation relative to plumb as well as the overall sagittal plane of the limb. Once both hind limbs have been observed, focus on the front limbs as the individual continues to walk away, paying particular attention to the carpus and the heel of each front foot. The heeled-out (spiral) deformity and bowed knee (varus carpus) become readily detectable by the trained eye as the individual moves away from you.
 

As the individual walks back to you, observe only the front limbs, one at a time, from the foot to the shoulder. Once again, place imaginary dots at each joint. Connect the imaginary lines between the dots as the limb flexes and extends and as the foot lands. Foals that are not broken to lead well are more difficult to observe, but with practice the eye can be trained to follow the dot system even at a trot.

Once the individual has been evaluated while moving, observe him standing as squarely as possible and in a relaxed position. Assign imaginary dots in the following 7 places (Fig. 2):

1. Center of toe
2. Center of coronary band
3. Center of fetlock
4. Center of the proximal cannon (note this dot will be superimposed over dot 5 unless axial deformity is present)
5. Center of the most distal aspect of the carpus
6. Center of the distal radius at the level of the physeal plate
7. Most proximal point on the forearm. A small swirl of hair is normally located at the top and center line of the radius.
    

While observing the dots, visualize an imaginary line between them and note any deviations of the lines. Next, imagine an imaginary laser or arrow centered on each dot, passing through it on the sagittal plane of the limb at that point. Observing these imaginary lines is a reliable, consistent method for identifying planes of deviation that can and often do occur between major joints. Using the dot system and observing the sagittal plane helps train the eye for details that may otherwise be missed, in addition to greatly enhancing communication between those observing the individual.

Limb deformities can be congenital or developmental, with varying degrees of deformity ranging from mild to severe. The majority of deformations will fall into one of five basic categories.

Angular

Angular deformities occur when the distal extremities of the limb deviate from the midline of the limb, normally occurring at the carpus or tarsus. Valgus deformity is a deviation lateral of the mid line. [...]