lock the knee in a sentence

1. In doing leg presses, a common error is to quickly extend the legs and lock the knees.
2. When the knee is in full extension, the femur slightly medially rotates on the tibia to lock the knee joint in place.
3. By night we were chewed up and spit out by some charm school ladies who cut our hair, taught us to walk all over again ( glide-- don't lock the knees ), and how to slip into and out of our topcoats still looking like ladies rather than disoriented orangutans.
4. It's difficult to find lock the knee in a sentence.