Weight-bearing upon flexed hocks puts enormous strain on all parts of the hock joint. Along with the equally complex stifle joint, the hock is crucial to the horse’s ability to flex and extend the hind limb and create the forward thrust that is the “impulsion” so often sought by horse owners who compete in the Olympic disciplines.

In the Western disciplines, the hock must stand up to sliding stops, rollbacks and bursting acceleration. Horses used for packing or trail riding must have hocks that will go all day, up and down steep hills, without rupture or fatigue.

The hock is structured by bones of peculiar shape. The tibial tarsal bone or astragalus upon whose oblique trochlea the distal end of the tibia rides also has a large shelf to support the deep digital flexor (DDF) tendon. The large fibular tarsal bone or calcaneus interlocks with the astragalus…