Non-Alignments : Offset, Rotation, & Deviation

These diagrams represent the "knee" (carpus) joint, but the principle can be applied to any of the joints from shoulder or hip downward in either the fore or the hind limb

There are only three possible mis-alignments of structural elements offsets, rotations, and deviations. In horses they may occur in any degree and in any combination. One, two, or all three types of misalignment commonly occur in the "knee" and fetlock joints of domestic horses.

To give you a sense of scale, the degree of rotation shown is seven (7) degrees, and the degree of deviation shown is also exactly seven (7) degrees. This is an important number, because it is the point at which veterinarians recommend that foals born with crooked legs be referred for surgical and/or orthopedic correction. 

Look for planes not lines.

#1 COW HOCKED

Hocks lie inside the plane: hoofs lie outside of it.

#2

OFTEN SAID TO BE CORRECT, BUT ACTUALLY BOW LEGGED.

#3

MORE OBVIOUSLY BOW LEGGED

In both these the hock lie outside the plane but the hoofs lie inside it.

#4

CORRECT

Stifles, hocks, fetlocks and hoofs all bisected by the plane.  Plane exits through cleft of frog.