Any angular deformity effects and is effected by the hooves the same way, but I'll discuss the “pigeon toe” (fetlock varus) in which the fetlock joint turns or deviates inward.
http://www.hoofrehab.com/Pigeon-toed.html

Toeing-In (Pigeon-Toed) The horse's toes point inward toward each other. Affected horses bear more weight on the outside of their feet, which places abnormal stresses on all of the structures located on the medial aspect of the limbs from the foot to the shoulder. These horses tend to "paddle" when moving, or swing their legs to the outside during the flight phase of the stride, then return back to the middle with the toe in when bearing weight.

http://www.thehorse.com/articles/26216/horse-conformation-co...