The patellar locking mechanism involves engagement of which ligament?

The patellar locking mechanism involves engagement of which ligament?

• A. Medial patellar ligament
• B. Lateral patellar ligament
• C. Cranial cruciate ligament
• D. Medial collateral ligament

Answer: (A)

The stay mechanism is created when the medial patellar ligament hooks the patella onto the medial trochlear ridge of the femur as the limb extends. This engagement holds the patella in place, allowing the limb to bear weight with little muscular effort and effectively “locking” the stifle. When the animal needs to move, the quadriceps contract to lift the patella away from the ridge, releasing the lock. The other ligaments listed stabilize the joint in different ways or provide lateral/cranial stability, but they do not form this locking action.

The stay mechanism is created when the medial patellar ligament hooks the patella onto the medial trochlear ridge of the femur as the limb extends. This engagement holds the patella in place, allowing the limb to bear weight with little muscular effort and effectively “locking” the stifle. When the animal needs to move, the quadriceps contract to lift the patella away from the ridge, releasing the lock. The other ligaments listed stabilize the joint in different ways or provide lateral/cranial stability, but they do not form this locking action.