The knee cap is the bone in the horse which sits just in front of the stifle. It helps support the stifle and enables tendons of the large muscles in the thigh to pass safely over the joint and attach on the tibia below, enabling the joint to extend as the horse moves.
The knee cap is also part of the ’stay apparatus’ which helps horse rest comfortably when standing up. When a horse wants to rest they move their leg so as to fix the knee cap in a locked position. In this way the horse does not have to expend energy using its muscles to stand up but relies on its tendons to hold it in position.
The main problem that occurs with knee caps occurs when they become too tightly fixed in the ’locked position’ and cannot be moved out so as to be able to move freely again. This condition is called ’upward fixation of the patella’ and results in lameness and distress. Such patella problems sometimes occur in horses that have not been fed well when young and whose joint have not developed properly. Vets may have to resort to surgery to treat such cases effectively but sometimes all that is necessary is gentle anti- inflammatories and products that improve thelubricating ability of the fluid within the stifle joint.