Is the knee locking mechanism present in animals? We study in human anatomy that when the knee is in full extension, the femur slightly medially rotates on the tibia to lock the knee joint in place. This reduces the work required to be done by the hefty thigh muscles. This happens in the knees in humans since they are the weight bearing joints. So, is the mechanism of locking present in other animals? If yes, is it even in the fore limbs or just the hind limbs?

Yes, the mechanism of patellar locking does occur in quadrupeds too. Although they are 4 limbed, a major portion of the weight is borne by the hind limbs. This is known as the stay apparatus and includes the mechanisms of Patellar locking, reciprocal mechanism and check apparatus.

On the other hand in the forelimb, although there is no locking mechanism as such, there exists a neat difference from the human anatomy. Human forelimbs are majorly adapted for manipulation but for quadrupeds, they are weight bearing. There exists what is called the stay apparatus - which includes the suspensory apparatus and the check apparatus.

For a detailed explanation for the interested reader, heres a helpful link - <