the middle joint of the leg that allows the leg to bend
The baby was crawling around on its hands and knees.
He got/went down on his knees (= got into a position where his knees were on the ground) in front of the altar.
Athletes often wear protective gear to prevent injuries to the knee.
Physical therapists guide patients through exercises to strengthen the knee.
Bending at the knee is a fundamental movement in various sports.
A sudden injury can cause swelling and pain in the knee joint.
