By Dr. Garrett Metcalf, DVM
It is common for most horse owners to experience a horse having a locked stifle, but when you see if for the first time it can be quite surprising and concerning.
First off, to understand why the stifle becomes locked we have to understand some of the basic parts of the stifle in a horse. You can equate the horse’s stifle to the human knee to some degree with some extra parts that humans do not have.
They have a kneecap or patella and the same bones that make up the stifle joint (Femur and Tibia) but with some significant anatomical distinction.
The difference is horses have three patellar ligaments compared to the human knee which only has one, and the horse has large trochlear ridges on the front part of the femur that the patella glides across. These ligaments tie the patella to the top of the tibia, and when the quadriceps muscles contract, it extends the stifle joint and the rest of the limb.