Part II: Arthrodesis of the Metacarpal/Metatarsal Phalangeal Joint in the Horse

1. Introduction
There are two primary indications for surgical arthrodesis of the fetlock joint: anatomic crippling of the joint to the point that joint function is disabled and weight bearing is not possible, and functional crippling of the joint to the point that joint function cannot occur without excessive pain and the horse chooses not to use the joint.

Conditions that result in anatomic crippling of the fetlock joint include: traumatic disruption of the suspensory apparatus of the fetlock joint, permanent non-responsive flexor contraction or laxity, fractures of the distal cannon bone or first phalanx that cannot be reconstructed to the point of function, and severe angulation as a result of growth deformity or malunion of a traumatic injury.^1,2  Conditions that cause functional crippling include previous infectious arthritis or ongoing degenerative arthritis that has resulted in destruction of the joint and causes such severe pain within the fetlock joint on weight bearing that the horse chooses not to use the joint because of the pain. In both conditions, the necessary goal is to restore function in the affected limb to prevent laminitis from overload weight bearing in the paired good limb. [...]